647 results on '"Tranquada, J. M."'
Search Results
2. Comment on newly found Charge Density Waves in infinite layer Nickelates
- Author
-
Pelliciari, J., Khan, N., Wasik, P., Barbour, A., Li, Y., Nie, Y., Tranquada, J. M., Bisogni, V., and Mazzoli, C.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science ,Condensed Matter - Other Condensed Matter ,Condensed Matter - Strongly Correlated Electrons - Abstract
Recent works[1-3] reported evidence for charge density waves (CDWs) in infinite layer nickelates (112 structure) based on resonant diffraction at the Ni $L_3$ edge measured at fixed scattering angle. We have found that a measurement with fixed momentum transfer, rather than scattering angle, does not show a resonance effect. We have also observed that a nearby structural Bragg peak from the substrate appears due to third harmonic content of the incident beam, and spreads intensity down to the region of the attributed CDW order. This was further confirmed by testing a bare substrate. We suggest procedures to confirm an effective resonant enhancement of a diffraction peak.
- Published
- 2023
3. Easy-plane multi-$\mathbf{q}$ magnetic ground state of Na$_3$Co$_2$SbO$_6$
- Author
-
Gu, Yuchen, Li, Xintong, Chen, Yue, Iida, Kazuki, Nakao, Akiko, Munakata, Koji, Garlea, V. Ovidiu, Li, Yangmu, Deng, Guochu, Zaliznyak, I. A., Tranquada, J. M., and Li, Yuan
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
Na$_3$Co$_2$SbO$_6$ is a potential Kitaev magnet with a monoclinic layered crystal structure. Recent investigations of the $C_3$-symmetric sister compound Na$_2$Co$_2$TeO$_6$ have uncovered a unique triple-$\mathbf{q}$ magnetic ground state, as opposed to a single-$\mathbf{q}$ (zigzag) one, prompting us to examine the influence of the reduced structural symmetry of Na$_3$Co$_2$SbO$_6$ on its ground state. Neutron diffraction data obtained on a twin-free crystal reveal that the ground state remains a multi-$\mathbf{q}$ state, despite the system's strong in-plane anisotropy. This robustness of multi-$\mathbf{q}$ orders suggests that they are driven by a common mechanism in the honeycomb cobaltates, such as higher-order magnetic interactions. Spin-polarized neutron diffraction results show that the ordered moments are entirely in-plane, with each staggered component orthogonal to the propagating wave vector. The inferred ground state favors a so-called XXZ easy-plane anisotropic starting point for the microscopic model over a Kitaev one, and features unequal ordered moments reduced by strong quantum fluctuations., Comment: 4 pages, 4 figures, plus Supplemental Material
- Published
- 2023
- Full Text
- View/download PDF
4. Designing the stripe-ordered cuprate phase diagram through uniaxial-stress
- Author
-
Guguchia, Z., Das, D., Simutis, G., Adachi, T., Küspert, J., Kitajima, N., Elender, M., Grinenko, V., Ivashko, O., Zimmermann, M. v., Müller, M., Mielke III, C., Hotz, F., Mudry, C., Baines, C., Bartkowiak, M., Shiroka, T., Koike, Y., Amato, A., Hicks, C. W., Gu, G. D., Tranquada, J. M., Klauss, H. -H., Chang, J. J., Janoschek, M., and Luetkens, H.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science ,Condensed Matter - Strongly Correlated Electrons - Abstract
The ability to efficiently control charge and spin in the cuprate high-temperature superconductors is crucial for fundamental research and underpins technological development. Here, we explore the tunability of magnetism, superconductivity and crystal structure in the stripe phase of the cuprate La_2-xBa_xCuO_4, with x = 0.115 and 0.135, by employing temperature-dependent (down to 400 mK) muon-spin rotation and AC susceptibility, as well as X-ray scattering experiments under compressive uniaxial stress in the CuO_2 plane. A sixfold increase of the 3-dimensional (3D) superconducting critical temperature T_c and a full recovery of the 3D phase coherence is observed in both samples with the application of extremely low uniaxial stress of 0.1 GPa. This finding demonstrates the removal of the well-known 1/8-anomaly of cuprates by uniaxial stress. On the other hand, the spin-stripe order temperature as well as the magnetic fraction at 400 mK show only a modest decrease under stress. Moreover, the onset temperatures of 3D superconductivity and spin-stripe order are very similar in the large stress regime. However, a substantial decrease of the magnetic volume fraction and a full suppression of the low-temperature tetragonal structure is found at elevated temperatures, which is a necessary condition for the development of the 3D superconducting phase with optimal T_c. Our results evidence a remarkable cooperation between the long-range static spin-stripe order and the underlying crystalline order with the three-dimensional fully coherent superconductivity. Overall, these results suggest that the stripe- and the SC order may have a common physical mechanism., Comment: 11 pages, 5 figures. This work builds on our earlier findings on LBCO, arXiv:2008.01159, and substantially expands it
- Published
- 2023
- Full Text
- View/download PDF
5. Structure of Charge Density Waves in La$_{1.875}$Ba$_{0.125}$CuO$_4$
- Author
-
Sears, J., Shen, Y., Krogstad, M. J., Miao, H., Bozin, E. S., Robinson, I. K., Gu, G. D., Osborn, R., Rosenkranz, S., Tranquada, J. M., and Dean, M. P. M.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Strongly Correlated Electrons - Abstract
Although charge-density wave (CDW) correlations exist in several families of cuprate supercon-ductors, they exhibit substantial variation in CDW wavevector and correlation length, indicating a key role for CDW-lattice interactions. We investigated this interaction in La$_{1.875}$Ba$_{0.125}$CuO$_4$ using single crystal x-ray diffraction to collect a large number of CDW peak intensities, and determined the Cu and La/Ba atomic distortions induced by the formation of CDW order. Within the CuO$_2$ planes, the distortions involve a periodic modulation of the Cu-Cu spacing along the direction of the ordering wave vector. The charge ordering within the copper-oxygen layer induces an out-of-plane breathing modulation of the surrounding lanthanum layers, which leads to a related distortion on the adjacent copper-oxygen layer. Our result implies that the CDW-related structural distortions do not remain confined to a single layer but rather propagate an appreciable distance through the crystal. This leads to overlapping structural modulations, in which CuO$_2$ planes exhibit distortions arising from the orthogonal CDWs in adjacent layers as well as distortions from the CDW within the layer itself. We attribute this striking effect to the weak c-axis charge screening in cuprates and suggest this effect could help couple the CDW between adjacent planes in the crystal., Comment: 9 pages; Accepted in Phys. Rev. B
- Published
- 2022
- Full Text
- View/download PDF
6. Spin canting and lattice symmetry in La$_2$CuO$_4$
- Author
-
Hu, Xiao, Sapkota, A., Galea, V. O., Gu, G. D., Zaliznyak, I. A., and Tranquada, J. M.
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
While the dominant magnetic interaction in La$_2$CuO$_4$ is superexchange between nearest-neighbor Cu moments, the pinning of the spin direction depends on weak anisotropic effects associated with spin-orbit coupling. The symmetry of the octahedral tilt pattern allows an out-of-plane canting of the Cu spins, which is compensated by an opposite canting in nearest-neighbor layers. A strong magnetic field applied perpendicular to the planes can alter the spin canting pattern to induce a weak ferromagnetic phase. In light of recent evidence that the lattice symmetry is lower than originally assumed, we take a new look at the nature of the field-induced spin-rotation transition. Comparing low-temperature neutron diffraction intensities for several magnetic Bragg peaks measured in fields of 0 and 14 T, we find that a better fit is provided by a model in which spins rotate within both neighboring planes but by different amounts, resulting in a noncollinear configuration. This model allows a more consistent relationship between lattice symmetry and spin orientation at all Cu sites., Comment: 8 pages, 6 figures; version accepted for publication
- Published
- 2022
- Full Text
- View/download PDF
7. Chern numbers of topological phonon band crossing determined with inelastic neutron scattering
- Author
-
Jin, Zhendong, Hu, Biaoyan, Liu, Yiran, Li, Yangmu, Zhang, Tiantian, Iida, Kazuki, Kamazawa, Kazuya, Kolesnikov, A. I., Stone, M. B., Zhang, Xiangyu, Chen, Haiyang, Wang, Yandong, Zaliznyak, I. A., Tranquada, J. M., Fang, Chen, and Li, Yuan
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Topological invariants in the band structure, such as Chern numbers, are crucial for the classification of topological matters and dictate the occurrence of exotic properties, yet their direct spectroscopic determination has been largely limited to electronic bands. Here, we use inelastic neutron scattering in conjunction with ab initio calculations to identify a variety of topological phonon band crossings in MnSi and CoSi single crystals. We find a distinct relation between the Chern numbers of a band-crossing node and the scattering intensity modulation in momentum space around the node. Given sufficiently high resolution, our method can be used to determine arbitrarily large Chern numbers of topological phonon band-crossing nodes., Comment: 14 pages, 9 figures including supplemental material
- Published
- 2022
- Full Text
- View/download PDF
8. Magnetic molecular orbitals in MnSi
- Author
-
Jin, Zhendong, Li, Yangmu, Hu, Zhigang, Hu, Biaoyan, Liu, Yiran, Iida, Kazuki, Kamazawa, Kazuya, Stone, M. B., Kolesnikov, A. I., Abernathy, D. L., Zhang, Xiangyu, Chen, Haiyang, Wang, Yandong, Fang, Chen, Wu, Biao, Zaliznyak, I. A., Tranquada, J. M., and Li, Yuan
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Mesoscale and Nanoscale Physics ,Physics - Atomic and Molecular Clusters - Abstract
A large body of knowledge about magnetism is attained from models of interacting spins, which usually reside on magnetic ions. Proposals beyond the ionic picture are uncommon and seldom verified by direct observations in conjunction with microscopic theory. Here, using inelastic neutron scattering to study the itinerant near-ferromagnet MnSi, we find that the system's fundamental magnetic units are interconnected, extended molecular orbitals consisting of three Mn atoms each, rather than individual Mn atoms. This result is further corroborated by magnetic Wannier orbitals obtained by ab initio calculations. It contrasts the ionic picture with a concrete example, and presents a novel regime of the spin waves where the wavelength is comparable to the spatial extent of the molecular orbitals. Our discovery brings important insights into not only the magnetism of MnSi, but also a broad range of magnetic quantum materials where structural symmetry, electron itinerancy and correlations act in concert., Comment: 27 pages, 27 figures including supplemental; comments are welcome
- Published
- 2022
- Full Text
- View/download PDF
9. Strongly-overdoped La$_{2-x}$Sr$_x$CuO$_4$: Evidence for Josephson-coupled grains of strongly-correlated superconductor
- Author
-
Li, Yangmu, Sapkota, A., Lozano, P. M., Du, Zengyi, Li, Hui, Wu, Zebin, Kundu, Asish K., Koch, R. J., Wu, Lijun, Winn, B. L., Chi, Songxue, Matsuda, M., Frontzek, M., Bozin, E. S., Zhu, Yimei, Bozovic, I., Pasupathy, Abhay N., Drozdov, Ilya K., Fujita, Kazuhiro, Gu, G. D., Zaliznyak, Igor, Li, Qiang, and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity - Abstract
The interpretation of how superconductivity disappears in cuprates at large hole doping has been controversial. To address this issue, we present an experimental study of single-crystal and thin film samples of La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) with $x\ge0.25$. In particular, measurements of bulk susceptibility on LSCO crystals with $x=0.25$ indicate an onset of diamagnetism at $T_{c1}=38.5$ K, with a sharp transition to a phase with full bulk shielding at $T_{c2}=18$ K, independent of field direction. Strikingly, the in-plane resistivity only goes to zero at $T_{c2}$. Inelastic neutron scattering on $x=0.25$ crystals confirms the presence of low-energy incommensurate magnetic excitations with reduced strength compared to lower doping levels. The ratio of the spin gap to $T_{c2}$ is anomalously large. Our results are consistent with a theoretical prediction for strongly overdoped cuprates by Spivak, Oreto, and Kivelson, in which superconductivity initially develops within disconnected self-organized grains characterized by a reduced hole concentration, with bulk superconductivity occurring only after superconductivity is induced by proximity effect in the surrounding medium of higher hole concentration. Beyond the superconducting-to-metal transition, local differential conductance measurements on an LSCO thin film suggest that regions with pairing correlations survive, but are too dilute to support superconducting order. Future experiments will be needed to test the degree to which these results apply to overdoped cuprates in general., Comment: 21 pages, 15 figures; added more sample characterizations, results for another sample, more discussion; accepted version
- Published
- 2022
- Full Text
- View/download PDF
10. Giant magnetic in-plane anisotropy and competing instabilities in Na3Co2SbO6
- Author
-
Li, Xintong, Gu, Yuchen, Chen, Yue, Garlea, V. Ovidiu, Iida, Kazuki, Kamazawa, Kazuya, Li, Yangmu, Deng, Guochu, Xiao, Qian, Zheng, Xiquan, Ye, Zirong, Peng, Yingying, Zaliznyak, I. A., Tranquada, J. M., and Li, Yuan
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Superconductivity - Abstract
We report magnetometry data obtained on twin-free single crystals of Na3Co2SbO6, which is considered a candidate material for realizing the Kitaev honeycomb model for quantum spin liquids. Contrary to a common belief that such materials can be modeled with the symmetries of an ideal honeycomb lattice, our data reveal a pronounced two-fold symmetry and in-plane anisotropy of over 200%, despite the honeycomb layer's tiny orthorhombic distortion of less than 0.2%. We further use magnetic neutron diffraction to elucidate a rich variety of field-induced phases observed in the magnetometry. These phases manifest themselves in the paramagnetic state as diffuse scattering signals associated with competing ferro- and antiferromagnetic instabilities, consistent with a theory that also predicts a quantum spin liquid phase nearby. Our results call for theoretical understanding of the observed in-plane anisotropy, and render Na3Co2SbO6 a promising ground for finding exotic quantum phases by targeted external tuning., Comment: 19 pages, 15 figures, 1 animation; to appear in Phys. Rev. X
- Published
- 2022
- Full Text
- View/download PDF
11. Evolution of magnetic stripes under uniaxial stress in La$_{1.885}$Ba$_{0.115}$CuO$_4$ studied by neutron scattering
- Author
-
Kamminga, Machteld E., Krighaar, Kristine M. L., Rømer, Astrid T., Sandberg, Lise Ø., Deen, Pascale P., Boehm, Martin, Gu, G. D., Tranquada, J. M., and Lefmann, Kim
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science - Abstract
Here we present the effect of uniaxial stress on the magnetic stripes in the cuprate system La$_{2-x}$Ba$_{x}$CuO$_4$ with $x = 0.115$, previously found to have a stress-induced enhancement in the superconducting transition temperature. By means of neutron scattering, we show that the static stripes are suppressed by stress, pointing towards a trade-off between superconductivity and static magnetism, in direct agreement with previously reported $\mu$SR measurements. Additionally, we show that some of the reduced weight in the elastic channel appears to have moved to the inelastic channel. Moreover, a stress-induced momentum shift of the fluctuations towards the typical 1/8 value of commensurability is observed. These results impose a strong constraint on the theoretical interpretation of stress-enhanced superconductivity in cuprate systems.
- Published
- 2022
- Full Text
- View/download PDF
12. Testing for pair-density-wave order in La$_{1.875}$Ba$_{0.125}$CuO$_4$
- Author
-
Lozano, P. M., Ren, Tianhao, Gu, G. D., Tsvelik, A. M., Tranquada, J. M., and Li, Qiang
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Strongly Correlated Electrons - Abstract
Charge order is commonly believed to compete with superconducting order. An intertwined form of superconducting wave function, known as pair-density-wave (PDW) order, has been proposed; however, there has been no direct evidence, theoretical or experimental, that it forms the ground state of any cuprate superconductor. As a test case, we consider \lbco\ with $x=1/8$, where charge and spin stripe orders within the CuO$_2$ planes compete with three-dimensional superconducting order. We report measurements of the superconducting critical current perpendicular to the planes in the presence of an in-plane magnetic field. The variation of the critical current with orientation of the field is inconsistent with a theoretical prediction specific to the PDW model. It appears, instead, that the orientation dependence of the critical-current density might be determined by a minority phase of $d$-wave superconductivity that is present as a consequence of doped-charge inhomogeneity., Comment: 6 pages, 2 figures, Major changes from previous version
- Published
- 2021
- Full Text
- View/download PDF
13. Superconductivity from charge order in cuprates
- Author
-
Tranquada, J. M., Dean, M. P. M., and Li, Qiang
- Subjects
Condensed Matter - Superconductivity - Abstract
Superconductivity in layered cuprates is induced by doping holes into a parent antiferromagnetic insulator. It is now recognized that another common emergent order involves charge stripes, and our understanding of the relationship between charge stripes and superconductivity has been evolving. Here we review studies of 214 cuprate families obtained by doping La$_2$CuO$_4$. Charge-stripe order tends to compete with bulk superconductivity; nevertheless, there is plentiful evidence that it coexists with two-dimensional superconductivity. This has been interpreted in terms of pair-density-wave superconductivity, and the perspective has shifted from competing to intertwined orders. In fact, a new picture of superconductivity based on pairing within charge stripes has been proposed, as we discuss., Comment: 10 pp, 12 figs, final version of special-topic invited review for JPSJ
- Published
- 2021
- Full Text
- View/download PDF
14. Reinvestigation of crystal symmetry and fluctuations in La$_2$CuO$_4$
- Author
-
Sapkota, A., Sterling, T. C., Lozano, P. M., Li, Yangmu, Cao, Huibo, Garlea, V. O., Reznik, D., Li, Qiang, Zaliznyak, I. A., Gu, G. D., and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science - Abstract
New surprises continue to be revealed about La$_2$CuO$_4$, the parent compound of the original cuprate superconductor. Here we present neutron scattering evidence that the structural symmetry is lower than commonly assumed. The static distortion results in anisotropic Cu-O bonds within the CuO$_2$ planes; such anisotropy is relevant to pinning charge stripes in hole-doped samples. Associated with the extra structural modulation is a soft phonon mode. If this phonon were to soften completely, the resulting change in CuO$_6$ octahedral tilts would lead to weak ferromagnetism. Hence, we suggest that this mode may be the "chiral" phonon inferred from recent studies of the thermal Hall effect. We also note the absence of interaction between the antiferromagnetic spin waves and low-energy optical phonons, in contrast to what is observed in hole-doped samples., Comment: 12 pages, 10 figures; accepted version
- Published
- 2021
- Full Text
- View/download PDF
15. Charge Condensation and Lattice Coupling Drives Stripe Formation in Nickelates
- Author
-
Shen, Y., Fabbris, G., Miao, H., Cao, Y., Meyers, D., Mazzone, D. G., Assefa, T., Chen, X. M., Kisslinger, K., Prabhakaran, D., Boothroyd, A. T., Tranquada, J. M., Hu, W., Barbour, A. M., Wilkins, S. B., Mazzoli, C., Robinson, I. K., and Dean, M. P. M.
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
Revealing the predominant driving force behind symmetry breaking in correlated materials is sometimes a formidable task due to the intertwined nature of different degrees of freedom. This is the case for La2-xSrxNiO4+{\delta} in which coupled incommensurate charge and spin stripes form at low temperatures. Here, we use resonant X-ray photon correlation spectroscopy to study the temporal stability and domain memory of the charge and spin stripes in La2-xSrxNiO4+{\delta}. Although spin stripes are more spatially correlated, charge stripes maintain a better temporal stability against temperature change. More intriguingly, charge order shows robust domain memory with thermal cycling up to 250 K, far above the ordering temperature. These results demonstrate the pinning of charge stripes to the lattice and that charge condensation is the predominant factor in the formation of stripe orders in nickelates., Comment: 7 pages; accepted in Physical Review Letters
- Published
- 2021
- Full Text
- View/download PDF
16. Cuprate superconductors as viewed through a striped lens
- Author
-
Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity - Abstract
Understanding the electron pairing in hole-doped cuprate superconductors has been a challenge, in particular because the "normal" state from which it evolves is unprecedented. Now, after three and a half decades of research, involving a wide range of experimental characterizations, it is possible to delineate a clear and consistent cuprate story. It starts with doping holes into a charge-transfer insulator, resulting in in-gap states. These states exhibit a pseudogap resulting from the competition between antiferromagnetic superexchange $J$ between nearest-neighbor Cu atoms (a real-space interaction) and the kinetic energy of the doped holes, which, in the absence of interactions, would lead to extended Bloch-wave states whose occupancy is characterized in reciprocal space. To develop some degree of coherence on cooling, the spin and charge correlations must self-organize in a cooperative fashion. A specific example of resulting emergent order is that of spin and charge stripes, as observed in La$_{2-x}$Ba$_x$CuO$_4$. While stripe order frustrates bulk superconductivity, it nevertheless develops pairing and superconducting order of an unusual character. The antiphase order of the spin stripes decouples them from the charge stripes, which can be viewed as hole-doped, two-leg, spin-$\frac12$ ladders. To achieve superconducting order, the pair correlations in neighboring ladders must develop phase order. In the presence of spin stripe order, antiphase Josephson coupling can lead to pair-density-wave superconductivity. Alternatively, in-phase superconductivity requires that the spin stripes have an energy gap, which empirically limits the coherent superconducting gap. Hence, superconducting order in the cuprates involves a compromise between the pairing scale, which is maximized at $x\sim\frac18$, and phase coherence, which is optimized at $x\sim0.2$., Comment: 74 pages, 24 figures; This article has been accepted for publication in Advances in Physics, published by Taylor & Francis; includes significant revisions and additions
- Published
- 2021
- Full Text
- View/download PDF
17. Experimental Evidence that Zn Impurities Pin Pair-Density-Wave Order in La$_{2-x}$Ba$_x$CuO$_4$
- Author
-
Lozano, P. M., Gu, G. D., Tranquada, J. M., and Li, Qiang
- Subjects
Condensed Matter - Superconductivity - Abstract
Both Zn-doping and $c$-axis magnetic fields have been observed to increase the spin stripe order in La$_{2-x}$Ba$_x$CuO$_4$ with $x$ close to 1/8. For $x=0.095$, the applied magnetic field also causes superconducting layers to decouple, presumably by favoring pair-density-wave order that consequently frustrates interlayer Josephson coupling. Here we show that introducing 1% Zn also leads to an initial onset of two-dimensional (2D) superconductivity, followed by 3D superconductivity at lower temperatures, even in zero field. We infer that the Zn pins pair-density-wave order locally, establishing the generality of such behavior., Comment: 6 pages, 4 figures; updated version, accepted as Letter in PRB
- Published
- 2020
- Full Text
- View/download PDF
18. Using uniaxial stress to probe the relationship between competing superconducting states in a cuprate with spin-stripe order
- Author
-
Guguchia, Z., Das, D., Wang, C. N., Adachi, T., Kitajima, N., Elender, M., Brückner, F., Ghosh, S., Grinenko, V., Shiroka, T., Müller, M., Mudry, C., Baines, C., Bartkowiak, M., Koike, Y., Amato, A., Tranquada, J. M., Klauss, H. -H., Hicks, C. W., and Luetkens, H.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science ,Condensed Matter - Strongly Correlated Electrons - Abstract
We report muon spin rotation and magnetic susceptibility experiments on in-plane stress effects on the static spin-stripe order and superconductivity in the cuprate system La2-xBaxCuO4 with x = 0.115. An extremely low uniaxial stress of 0.1 GPa induces a substantial decrease in the magnetic volume fraction and a dramatic rise in the onset of 3D superconductivity, from 10 to 32 K; however, the onset of at-least-2D superconductivity is much less sensitive to stress. These results show not only that large-volume-fraction spin-stripe order is anti-correlated with 3D superconducting (SC) coherence, but also that these states are energetically very finely balanced. Moreover, the onset temperatures of 3D superconductivity and spin-stripe order are very similar in the large stress regime. These results strongly suggest a similar pairing mechanism for spin-stripe order, the spatially-modulated 2D and uniform 3D SC orders, imposing an important constraint on theoretical models., Comment: To appear in Physical Review Letters (2020)
- Published
- 2020
- Full Text
- View/download PDF
19. Electron-phonon coupling and superconductivity in the doped topological-crystalline insulator (Pb$_{0.5}$Sn$_{0.5}$)$_{1-x}$In$_x$Te
- Author
-
Sapkota, A., Li, Y., Winn, B. L., Podlesnyak, A., Xu, Guangyong, Xu, Zhijun, Ran, Kejing, Chen, Tong, Sun, Jian, Wen, Jinsheng, Wu, Lihua, Yang, Jihui, Li, Qiang, Gu, G. D., and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Strongly Correlated Electrons - Abstract
We present a neutron scattering study of phonons in single crystals of (Pb$_{0.5}$Sn$_{0.5}$)$_{1-x}$In$_x$Te with $x=0$ (metallic, but nonsuperconducting) and $x=0.2$ (nonmetallic normal state, but superconducting). We map the phonon dispersions (more completely for $x=0$) and find general consistency with theoretical calculations, except for the transverse and longitudinal optical (TO and LO) modes at the Brillouin zone center. At low temperature, both modes are strongly damped but sit at a finite energy ($\sim4$ meV in both samples), shifting to higher energy at room temperature. These modes are soft due to a proximate structural instability driven by the sensitivity of Pb-Te and Sn-Te $p$-orbital hybridization to off-center displacements of the metal atoms. The impact of the soft optical modes on the low-energy acoustic modes is inferred from the low thermal conductivity, especially at low temperature. Given that the strongest electron-phonon coupling is predicted for the LO mode, which should be similar for both studied compositions, it is intriguing that only the In-doped crystal is superconducting. In addition, we observe elastic diffuse (Huang) scattering that is qualitatively explained by the difference in Pb-Te and Sn-Te bond lengths within the lattice of randomly distributed Pb and Sn sites. We also confirm the presence of anomalous diffuse low-energy atomic vibrations that we speculatively attribute to local fluctuations of individual Pb atoms between off-center sites.
- Published
- 2020
- Full Text
- View/download PDF
20. Charge density waves in cuprate superconductors beyond the critical doping
- Author
-
Miao, H., Fabbris, G., Koch, R. J., Mazzone, D. G., Nelson, C. S., Acevedo-Esteves, R., Li, Y., Gu, G. D., Yilmaz, T., Kaznatcheev, K., Vescovo, E., Oda, M., Kurosawa, K., Momono, N., Assefa, T. A., Robinson, I. K., Bozin, E., Tranquada, J. M., Johnson, P. D., and Dean, M. P. M.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Strongly Correlated Electrons - Abstract
The unconventional normal-state properties of the cuprates are often discussed in terms of emergent electronic order that onsets below a putative critical doping of xc = 0.19. Charge-density wave (CDW) correlations represent one such order; however, experimental evidence for such order generally spans a limited range of doping that falls short of the critical value xc, leading to questions regarding its essential relevance. Here, we use x-ray diffraction to demonstrate that CDW correlations in La2-xSrxCuO4 persist up to a doping of at least x = 0.21. The correlations show strong changes through the superconducting transition, but no obvious discontinuity through xc = 0.19, despite changes in Fermi surface topology and electronic transport at this doping. These results demonstrate the interaction between CDWs and superconductivity even in overdoped cuprates and prompt a reconsideration of the role of CDW correlations in the high-temperature cuprate phase diagram., Comment: 8 pages + 5 pages of supplemental material; accepted in npj Quantum Materials
- Published
- 2020
- Full Text
- View/download PDF
21. Observation of the Magnon Polarization
- Author
-
Nambu, Y., Barker, J., Okino, Y., Kikkawa, T., Shiomi, Y., Enderle, M., Weber, T., Winn, B., Graves-Brook, M., Tranquada, J. M., Ziman, T., Fujita, M., Bauer, G. E. W., Saitoh, E., and Kakurai, K.
- Subjects
Condensed Matter - Materials Science - Abstract
We measure the mode-resolved direction of the precessional motion of the magnetic order, i.e., magnon polarization, via the chiral term of inelastic polarized neutron scattering spectra. The magnon polarisation is important in spintronics, affecting thermodynamic properties such as the magnitude and sign of the spin Seebeck effect. The observation of both signs of magnon polarization in Y3Fe5O12 also gives direct proof of its ferrimagnetic nature. The experiments agree very well with atomistic simulations of the scattering cross section., Comment: 6 pages, 4 figures
- Published
- 2019
- Full Text
- View/download PDF
22. Scaling Behaviour of Low-Temperature Orthorhombic Domains in Prototypical High-Temperature Superconductor La$_{1.875}$Ba$_{0.125}$CuO$_{4}$
- Author
-
Assefa, T. A., Cao, Y., Diao, J., Kisslinger, K., Gu, G. D., Tranquada, J. M., Dean, M. P. M., and Robinson, I. K.
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science - Abstract
Translational/rotational symmetry breaking and recovery in condensed matter systems are closely related to exotic physical properties such as superconductivity (SC), magnetism, spin density waves (SDW) and charge density waves (CDW). The interplay between different order parameters is intricate and often subject to intense debate, as in the case of CDW order and superconductivity. In La1:875Ba0:125CuO4 (LBCO), the locations of CDW domains are found to be pinned on the nanometer size scale. Coherent X-ray diffraction techniques open routes to directly visualize the domain structures associated with these symmetry changes. We have pushed Bragg Coherent Diffractive Imaging (BCDI) into the cryogenic regime where most phase transitions in quantum materials reside. Utilizing BCDI, we image the structural evolution of LBCO microcrystal samples during the high-temperature-tetragonal (HTT) to low-temperature-orthorhombic (LTO) phase transition. Our results show the formation of LTO domains close to the transition temperature and how the domain size varies with temperature. The LTO domain size is shown to decrease with temperature and to be inversely proportional to the magnitude of the orthorhombic distortion. The number of domains follows the secondary order parameter (or orthorhombic strain) measurement with a critical exponent that is consistent with the 3D universality class.
- Published
- 2019
- Full Text
- View/download PDF
23. Nature and impact of stripe freezing in La$_{1.67}$Sr$_{0.33}$NiO$_4$
- Author
-
Merritt, A. M., Reznik, D., Garlea, V. O., Gu, G. D., and Tranquada, J. M.
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
La$_{1.67}$Sr$_{0.33}$NiO$_4$ develops charge and spin stripe orders at temperatures of roughly 200 K, with modulation wave vectors that are temperature independent. Various probes of spin and charge response have provided independent evidence for some sort of change below $\sim50$ K. In combination with a new set of neutron scattering measurements, we propose a unified interpretation of all of these observations in terms of a freezing of Ni-centered charges stripes, together with a glassy ordering of the spin stripes that shows up in neutron scattering as a slight rotation of the average spin direction., Comment: 9 pages, 6 figs; version accepted for publication
- Published
- 2019
- Full Text
- View/download PDF
24. Signatures of coupling between spin waves and Dirac fermions in YbMnBi$_2$
- Author
-
Sapkota, A., Classen, L., Stone, M. B., Savici, A. T., Garlea, V. O., Wang, Aifeng, Tranquada, J. M., Petrovic, C., and Zaliznyak, I. A.
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
We present inelastic neutron scattering (INS) measurements of magnetic excitations in YbMnBi$_2$, which reveal features consistent with a direct coupling of magnetic excitations to Dirac fermions. In contrast with the large broadening of magnetic spectra observed in antiferromagnetic metals such as the iron pnictides, here the spin waves exhibit a small but resolvable intrinsic width, consistent with our theoretical analysis. The subtle manifestation of spin-fermion coupling is a consequence of the Dirac nature of the conduction electrons, including the vanishing density of states near the Dirac points. Accounting for the Dirac fermion dispersion specific to \ymb\ leads to particular signatures, such as the nearly wave-vector independent damping observed in the experiment., Comment: 8 pages, 11 figures including both main text and supplemental material
- Published
- 2019
- Full Text
- View/download PDF
25. Magnetism and superconductivity in Fe$_{1+y}$Te$_{1-x}$Se$_x$
- Author
-
Tranquada, J. M., Xu, Guangyong, and Zaliznyak, I. A.
- Subjects
Condensed Matter - Superconductivity - Abstract
Neutron scattering has played a significant role in characterizing magnetic and structural correlations in Fe$_{1+y}$Te$_{1-x}$Se$_x$ and their connections with superconductivity. Here we review several key aspects of the physics of iron chalcogenide superconductors where neutron studies played a key role. These topics include the phase diagram of Fe$_{1+y}$Te$_{1-x}$Se$_{x}$, where the doping-dependence of structural transitions can be understood from a mapping to the anisotropic random field Ising model. We then discuss orbital-selective Mott physics in the Fe chalcogenide series, where temperature-dependent magnetism in the parent material provided one of the earliest cases for orbital-selective correlation effects in a Hund's metal. Finally, we elaborate on the character of local magnetic correlations revealed by neutron scattering, its dependence on temperature and composition, and the connections to nematicity and superconductivity., Comment: 15 pp, 16 figs
- Published
- 2019
- Full Text
- View/download PDF
26. Empirical case for two pseudogaps in cuprate superconductors
- Author
-
Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity - Abstract
Superconductivity in cuprates is achieved by doping holes into a correlated charge-transfer insulator. While the correlated character of the parent insulator is now understood, there is no accepted theory for the "normal" state of the doped insulator. I present a mostly empirical analysis of a large range of experimental characterizations, making the case for two pseudogaps: (1) a large pseudogap resulting from the competition between the energy of superexchange-coupled local Cu moments and the kinetic energy of doped holes; (2) a small pseudogap that results from dopant disorder and consequent variations in local charge density, leading to a distribution of local superconducting onset temperatures. The large pseudogap closes as hole kinetic energy dominates at higher doping and the dynamic antiferromagnetic correlations become overdamped. Establishing spatially-homogeneous $d$-wave superconductivity is limited by those regions with the weakest superconducting phase coherence, which tends to be limited by low-energy spin fluctuations. The magnitude of the small pseudogap is correlated with the doping-dependent energy $E_{\rm cross}$ associated with the neck of the hour-glass dispersion of spin excitations. The consequences of this picture are discussed., Comment: 17 pages, 8 figures
- Published
- 2019
27. Gapless spin excitations in superconducting La$_{2-x}$Ca$_{1+x}$Cu$_{2}$O$_{6}$ with $T_c$ up to 55 K
- Author
-
Schneeloch, John A., Zhong, Ruidan, Stone, M. B., Zaliznyak, I. A., Gu, G. D., Xu, Guangyong, and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity - Abstract
We report inelastic neutron scattering on single crystals of the bilayer cuprate family La$_{2-x}$Ca$_{1+x}$Cu$_{2}$O$_{6+\delta}$, including two crystals made superconducting (transitions at 45 and 55 K) by high-pressure annealing in an oxygen-containing atmosphere. The magnetic excitations in the non-superconducting crystal have a similar temperature-dependence as those in weakly hole-doped cuprates. In the superconducting crystals, there is a near-uniform suppression of the magnetic spectral weight with increasing temperature; in particular, there are no signs of a spin gap or "resonance" peak. This is different from the temperature dependence seen in many optimally-doped cuprates but similar to the behavior seen in certain underdoped cuprates. We discuss the possible connection with pair-density-wave superconductivity., Comment: 11 pp, 8 figs, revised version, accepted in PRB
- Published
- 2019
- Full Text
- View/download PDF
28. From nonmetal to strange metal at the stripe-percolation transition in La2−xSrxCuO4
- Author
-
Tranquada, J. M., primary, Lozano, P. M., additional, Yao, Juntao, additional, Gu, G. D., additional, and Li, Qiang, additional
- Published
- 2024
- Full Text
- View/download PDF
29. Tuning from failed superconductor to failed insulator with magnetic field
- Author
-
Li, Yangmu, Terzic, J., Baity, P. G., Popović, Dragana, Gu, G. D., Li, Qiang, Tsvelik, A. M., and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity - Abstract
Do charge modulations compete with electron pairing in high-temperature copper-oxide superconductors? We investigated this question by suppressing superconductivity in a stripe-ordered cuprate compound at low temperature with high magnetic fields. With increasing field, loss of three-dimensional superconducting order is followed by reentrant two-dimensional superconductivity and then an ultra-quantum metal phase. Circumstantial evidence suggests that the latter state is bosonic and associated with the charge stripes. These results provide experimental support to the theoretical perspective that local segregation of doped holes and antiferromagnetic spin correlations underlies the electron-pairing mechanism in cuprates., Comment: 20 pp, 4 figs.; accepted version; for open-access published version, click on DOI below
- Published
- 2018
- Full Text
- View/download PDF
30. Persistent Charge Density Wave Memory in a Cuprate Superconductor
- Author
-
Chen, X. M., Mazzoli, C., Cao, Y., Thampy, V., Barbour, A. M., Hu, W., Lu, M., Assefa, T., Miao, H., Fabbris, G., Gu, G. D., Tranquada, J. M., Dean, M. P. M., Wilkins, S. B., and Robinson, I. K.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Strongly Correlated Electrons - Abstract
Although charge density wave (CDW) correlations appear to be a ubiquitous feature of the superconducting cuprates, their disparate properties suggest a crucial role for coupling or pinning of the CDW to lattice deformations and disorder. While diffraction intensities can demonstrate the occurrence of CDW domain formation, the lack of scattering phase information has limited our understanding of this process. Here, we report coherent resonant x-ray speckle correlation analysis, which directly determines the reproducibility of CDW domain patterns in La1.875Ba0.125CuO4 (LBCO 1/8) with thermal cycling. While CDW order is only observed below 54 K, where a structural phase transition results in equivalent Cu-O bonds, we discover remarkably reproducible CDW domain memory upon repeated cycling to temperatures well above that transition. That memory is only lost on cycling across the transition at 240(3) K that restores the four-fold symmetry of the copper-oxide planes. We infer that the structural-domain twinning pattern that develops below 240 K determines the CDW pinning landscape below 54 K. These results open a new view into the complex coupling between charge and lattice degrees of freedom in superconducting cuprates., Comment: 7 pages; 4 figures
- Published
- 2018
- Full Text
- View/download PDF
31. Low-energy antiferromagnetic spin fluctuations limit the coherent superconducting gap in cuprates
- Author
-
Li, Yangmu, Zhong, Ruidan, Stone, M. B., Kolesnikov, A. I., Gu, G. D., Zaliznyak, I. A., and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity - Abstract
Motivated by recent attention to a potential antiferromagnetic quantum critical point at $x_c\sim 0.19$, we have used inelastic neutron scattering to investigate the low-energy spin excitations in crystals of La$_{2-x}$Sr$_x$CuO$_4$ bracketing $x_c$. We observe a peak in the normal-state spin-fluctuation weight at $\sim20$~meV for both $x=0.21$ and 0.17, inconsistent with quantum critical behavior. The presence of the peak raises the question of whether low-energy spin fluctuations limit the onset of superconducting order. Empirically evaluating the spin gap $\Delta_{\rm spin}$ in the superconducting state, we find that $\Delta_{\rm spin}$ is equal to the coherent superconducting gap $\Delta_c$ determined by electronic spectroscopies. To test whether this is a general result for other cuprate families, we have checked through the literature and find that $\Delta_c\le\Delta_{\rm spin}$ for cuprates with uniform $d$-wave superconductivity. We discuss the implications of this result., Comment: 11 pages, 8 figures, 1 table; accepted version
- Published
- 2018
- Full Text
- View/download PDF
32. Unusual phonon density of states and response to the superconducting transition in the In-doped topological crystalline insulator Pb$_{0.5}$Sn$_{0.5}$Te
- Author
-
Ran, Kejing, Zhong, Ruidan, Chen, Tong, Gan, Yuan, Wang, Jinghui, Winn, B. L., Christianson, A. D., Li, Shichao, Ma, Zhen, Bao, Song, Cai, Zhengwei, Xu, Guangyong, Tranquada, J. M., Gu, Genda, Sun, Jian, and Wen, Jinsheng
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science ,Condensed Matter - Strongly Correlated Electrons - Abstract
We present inelastic neutron scattering results of phonons in (Pb$_{0.5}$Sn$_{0.5}$)$_{1-x}$In$_x$Te powders, with $x=0$ and 0.3. The $x=0$ sample is a topological crystalline insulator, and the $x=0.3$ sample is a superconductor with a bulk superconducting transition temperature $T_c$ of 4.7 K. In both samples, we observe unexpected van Hove singularities in the phonon density of states at energies of 1--2.5 meV, suggestive of local modes. On cooling the superconducting sample through $T_c$, there is an enhancement of these features for energies below twice the superconducting-gap energy. We further note that the superconductivity in (Pb$_{0.5}$Sn$_{0.5}$)$_{1-x}$In$_x$Te occurs in samples with normal-state resistivities of order 10 m$\Omega$~cm, indicative of bad-metal behavior. Calculations based on density functional theory suggest that the superconductivity is easily explainable in terms of electron-phonon coupling; however, they completely miss the low-frequency modes and do not explain the large resistivity. While the bulk superconducting state of (Pb$_{0.5}$Sn$_{0.5}$)$_{0.7}$In$_{0.3}$Te appears to be driven by phonons, a proper understanding will require ideas beyond simple BCS theory., Comment: 6 pages, 5 figures, published as a PRB Rapid Communication
- Published
- 2018
- Full Text
- View/download PDF
33. Coexistence of superconductivity and short-range double-stripe spin correlations in Te-vapor annealed FeTe$_{1-x}$Se$_{x}$ with $x\le0.2$
- Author
-
Xu, Zhijun, Schneeloch, J. A., Yi, Ming, Zhao, Yang, Matsuda, Masaaki, Pajerowski, D. M., Chi, Songxue, Birgeneau, R. J., Gu, Genda, Tranquada, J. M., and Xu, Guangyong
- Subjects
Condensed Matter - Superconductivity - Abstract
In as-grown bulk crystals of Fe$_{1+y}$Te$_{1-x}$Se$_{x}$ with $x\lesssim0.3$, excess Fe ($y>0$) is inevitable and correlates with a suppression of superconductivity. At the same time, there remains the question as to whether the character of the antiferromagnetic correlations associated with the enhanced anion height above the Fe planes in Te-rich samples is compatible with superconductivity. To test this, we have annealed as-grown crystals with $x=0.1$ and 0.2 in Te vapor, effectively reducing the excess Fe and inducing bulk superconductivity. Inelastic neutron scattering measurements reveal low-energy magnetic excitations consistent with short-range correlations of the double-stripe type; nevertheless, cooling into the superconducting state results in a spin gap and a spin resonance, with the extra signal in the resonance being short-range with a mixed single-stripe/double-stripe character, which is different than other iron-based superconductors. The mixed magnetic character of these superconducting samples does not appear to be trivially explainable by inhomogeneity., Comment: 6 pages, 6 figures
- Published
- 2018
- Full Text
- View/download PDF
34. Electron and hole contributions to normal-state transport in the superconducting system Sn$_{1-x}$In$_x$Te
- Author
-
Zhang, Cheng, He, Xu-Gang, Chi, Hang, Zhong, Ruidan, Ku, Wei, Gu, Genda, Tranquada, J. M., and Li, Qiang
- Subjects
Condensed Matter - Superconductivity - Abstract
Indium-doped SnTe has been of interest because the system can exhibit both topological surface states and bulk superconductivity. While the enhancement of the superconducting transition temperature is established, the character of the electronic states induced by indium doping remains poorly understood. We report a study of magneto-transport in a series of Sn$_{1-x}$In$_x$Te single crystals with $0.1\le x \le 0.45$. From measurements of the Hall effect, we find that the dominant carrier type changes from hole-like to electron-like at $x\sim0.25$; one would expect electron-like carriers if the In ions have a valence of $+3$. For single crystals with $x = 0.45$, corresponding to the highest superconducting transition temperature, pronounced Shubnikov-de Haas oscillations are observed in the normal state. In measurements of magnetoresistance, we find evidence for weak anti-localization (WAL). We attribute both the quantum oscillations and the WAL to bulk Dirac-like hole pockets, previously observed in photoemission studies, which coexist with the dominant electron-like carriers., Comment: 8 pages, 7 figures; accepted version
- Published
- 2018
- Full Text
- View/download PDF
35. Evidence for magnetic-field-induced decoupling of superconducting bilayers in La$_{2-x}$Ca$_{1+x}$Cu$_{2}$O$_{6}$
- Author
-
Zhong, Ruidan, Schneeloch, J. A., Chi, Hang, Li, Qiang, Gu, Genda, and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity - Abstract
We report a study of magnetic susceptibility and electrical resistivity as a function of temperature and magnetic field in superconducting crystals of La$_{2-x}$Ca$_{1+x}$Cu$_{2}$O$_{6}$ with $x=0.10$ and 0.15 and transition temperature $T_{c}^{\rm m} = 54$ K (determined from the susceptibility). When an external magnetic field is applied perpendicular to the CuO$_2$ bilayers, the resistive superconducting transition measured with currents flowing perpendicular to the bilayers is substantially lower than that found with currents flowing parallel to the bilayers. Intriguingly, this anisotropic behavior is quite similar to that observed for the magnetic irreversibility points with the field applied either perpendicular or parallel to the bilayers. We discuss the results in the context of other studies that have found evidence for the decoupling of superconducting layers induced by a perpendicular magnetic field., Comment: 8 pages, 5 figures; version accepted for publication in PRB
- Published
- 2018
- Full Text
- View/download PDF
36. Growth and structural characterization of large superconducting crystals of La$_{2-x}$Ca$_{1+x}$Cu$_2$O$_{6}$
- Author
-
Schneeloch, J. A., Guguchia, Z., Stone, M. B., Tian, Wei, Zhong, Ruidan, Mohanty, K. M., Xu, Guangyong, Gu, G. D., and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity - Abstract
Large crystals of La$_{2-x}$Ca$_{1+x}$Cu$_2$O$_{6}$ (La-Ca-2126) with $x=0.10$ and 0.15 have been grown and converted to bulk superconductors by high-pressure oxygen annealing. The superconducting transition temperature, $T_c$, is as high as 55~K; this can be raised to 60~K by post-annealing in air. Here we present structural and magnetic characterizations of these crystals using neutron scattering and muon spin rotation techniques. While the as-grown, non-superconducting crystals are single phase, we find that the superconducting crystals contain 3 phases forming coherent domains stacked along the $c$ axis: the dominant La-Ca-2126 phase, very thin (1.5 unit-cell) intergrowths of La$_2$CuO$_4$, and an antiferromagnetic La$_8$Cu$_8$O$_{20}$ phase. We propose that the formation and segregation of the latter phases increases the Ca concentration of the La-Ca-2126, thus providing the hole-doping that supports superconductivity., Comment: 9 pages, 8 figures, version accepted in PRMaterials
- Published
- 2017
- Full Text
- View/download PDF
37. Suppression of the antiferromagnetic order when approaching the superconducting state in a phase-separated crystal of K$_x$Fe$_{2-y}$Se$_2$
- Author
-
Li, Shichao, Gan, Yuan, Wang, Jinghui, Zhong, Ruidan, Schneeloch, J. A., Xu, Zhijun, Tian, Wei, Stone, M. B., Chi, Songxue, Matsuda, M., Sidis, Y., Bourges, Ph., Li, Qiang, Gu, Genda, Tranquada, J. M., Xu, Guangyong, Birgeneau, R. J., and Wen, Jinsheng
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Strongly Correlated Electrons - Abstract
We have combined elastic and inelastic neutron scattering techniques, magnetic susceptibility and resistivity measurements to study single-crystal samples of K$_x$Fe$_{2-y}$Se$_2$, which contain the superconducting phase that has a transition temperature of $\sim$31 K. In the inelastic neutron scattering measurements, we observe both the spin-wave excitations resulting from the block antiferromagnetic ordered phase and the resonance that is associated with the superconductivity in the superconducting phase, demonstrating the coexistence of these two orders. From the temperature dependence of the intensity of the magnetic Bragg peaks, we find that well before entering the superconducting state, the development of the magnetic order is interrupted, at $\sim$42 K. We consider this result to be evidence for the physical separation of the antiferromagnetic and superconducting phases; the suppression is possibly due to the proximity effect of the superconducting fluctuations on the antiferromagnetic order., Comment: To appear in PRB
- Published
- 2017
- Full Text
- View/download PDF
38. Unexpected Enhancement of Three-Dimensional Low-Energy Spin Correlations in Quasi-Two-Dimensional Fe$_{1+y}$Te$_{1-x}$Se$_{x}$ System at High Temperature
- Author
-
Xu, Zhijun, Schneeloch, J. A., Wen, Jinsheng, Winn, B. L., Granroth, G. E., Zhao, Yang, Gu, Genda, Zaliznyak, Igor, Tranquada, J. M., Birgeneau, R. J., and Xu, Guangyong
- Subjects
Condensed Matter - Superconductivity - Abstract
We report inelastic neutron scattering measurements of low energy ($\hbar \omega < 10$ meV) magnetic excitations in the "11" system Fe$_{1+y}$Te$_{1-x}$Se$_{x}$. The spin correlations are two-dimensional (2D) in the superconducting samples at low temperature, but appear much more three-dimensional when the temperature rises well above $T_c \sim 15$ K, with a clear increase of the (dynamic) spin correlation length perpendicular to the Fe planes. The spontaneous change of dynamic spin correlations from 2D to 3D on warming is unexpected and cannot be naturally explained when only the spin degree of freedom is considered. Our results suggest that the low temperature physics in the "11" system, in particular the evolution of low energy spin excitations towards %better satisfying the nesting condition for mediating superconducting pairing, is driven by changes in orbital correlations.
- Published
- 2017
- Full Text
- View/download PDF
39. Complementary response of static spin-stripe order and superconductivity to non-magnetic impurities in cuprates
- Author
-
Guguchia, Z., Roessli, B., Khasanov, R., Amato, A., Pomjakushina, E., Conder, K., Uemura, Y. J., Tranquada, J. M., Keller, H., and Shengelaya, A.
- Subjects
Condensed Matter - Superconductivity - Abstract
We report muon-spin rotation and neutron-scattering experiments on non-magnetic Zn impurity effects on the static spin-stripe order and superconductivity of the La214 cuprates. Remarkably, it was found that, for samples with hole doping x = 1/8, the spin-stripe ordering temperature T_so decreases linearly with Zn doping y and disappears at around y = 4\%, demonstrating a high sensitivity of static spin-stripe order to impurities within a CuO_2 plane. Moreover, T_so is suppressed by Zn in the same manner as is the superconducting transition temperature T_c for samples near optimal hole doping. This surprisingly similar sensitivity suggests that the spin-stripe order is dependent on intertwining with superconducting correlations., Comment: 9 pages and 9 figures
- Published
- 2017
- Full Text
- View/download PDF
40. Static Charge Density Wave Order in the Superconducting State of La2-xBaxCuO4
- Author
-
Thampy, V., Chen, X. M., Cao, Y., Mazzoli, C., Barbour, A. M., Hu, W., Miao, H., Fabbris, G., Zhong, R. D., Gu, G. D., Tranquada, J. M., Robinson, I. K., Wilkins, S. B., and Dean, M. P. M.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Strongly Correlated Electrons - Abstract
Charge density wave (CDW) correlations feature prominently in the phase diagram of the cuprates, motivating competing theories of whether fluctuating CDW correlations aid superconductivity or whether static CDW order coexists with superconductivity in inhomogeneous or spatially modulated states. Here we report Cu $L$-edge resonant x-ray photon correlation spectroscopy (XPCS) measurements of CDW correlations in superconducting La$_{2-x}$Ba$_x$CuO$_4$ $x=0.11$. Static CDW order is shown to exist in the superconducting state at low temperatures and to persist up to at least 85\% of the CDW transition temperature. We discuss the implications of our observations for how \emph{nominally} competing order parameters can coexist in the cuprates., Comment: 6 pages, 5 figures, Accepted in Phys. Rev. B Rapid Communications
- Published
- 2017
- Full Text
- View/download PDF
41. In-plane multi- q magnetic ground state of Na3Co2SbO6
- Author
-
Gu, Yuchen, primary, Li, Xintong, additional, Chen, Yue, additional, Iida, Kazuki, additional, Nakao, Akiko, additional, Munakata, Koji, additional, Garlea, V. Ovidiu, additional, Li, Yangmu, additional, Deng, Guochu, additional, Zaliznyak, I. A., additional, Tranquada, J. M., additional, and Li, Yuan, additional
- Published
- 2024
- Full Text
- View/download PDF
42. Giant Spin Gap and Magnon Localization in the Disordered Heisenberg Antiferromagnet Sr2Ir1-xRuxO4
- Author
-
Cao, Yue, Liu, Xuerong, Xu, Wenhu, Yin, Weiguo, Meyers, D., Kim, Jungho, Casa, Diego, Upton, Mary, Gog, Thomas, Berlijn, Tom, Alvarez, Gonzalo, Yuan, Shujuan, Terzic, Jasminka, Tranquada, J. M., Hill, John P., Cao, Gang, Konik, Robert M., and Dean, M. P. M.
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
We study the evolution of magnetic excitations in the disordered two-dimensional antiferromagnet Sr2Ir1-xRuxO4. A gigantic magnetic gap greater than 40 meV opens at x = 0.27 and increases with Ru concentration, rendering the dispersive magnetic excitations in Sr2IrO4 almost momentum independent. Up to a Ru concentration of x = 0.77, both experiments and first-principles calculations show the Ir Jeff = 1/2 state remains intact. The magnetic gap arises from the local interaction anisotropy in the proximity of the Ru disorder. Under the coherent potential approximation, we reproduce the experimental magnetic excitations using the disordered Heisenberg antiferromagnetic model with suppressed next-nearest neighbor ferromagnetic coupling., Comment: 6 pages, 4 figures
- Published
- 2016
- Full Text
- View/download PDF
43. Evidence for a nematic phase in La$_{1.75}$Sr$_{0.25}$NiO$_{4}$
- Author
-
Zhong, Ruidan, Winn, Barry L., Gu, Genda, Reznik, Dmitry, and Tranquada, J. M.
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
Determining the nature of electronic states in doped Mott insulators remains a challenging task. In the case of tetragonal La$_{2-x}$Sr$_{x}$NiO$_{4}$, the occurrence of diagonal charge and spin stripe order in the ground state is now well established. In contrast, the nature of the high-temperature "disordered" state from which the stripe order develops has long been a subject of controversy, with considerable speculation regarding a polaronic liquid. Following on the recent detection of dynamic charge stripes, we use neutron scattering measurements on an $x=0.25$ crystal to demonstrate that the dispersion of the charge stripe excitations is anisotropic. This observation provides compelling evidence for the presence of electronic nematic order., Comment: 6 pages, 4 figures, plus supplemental 3 pages with 2 figures; final version accepted for publication
- Published
- 2016
- Full Text
- View/download PDF
44. Remarkable Stability of Charge Density Wave Order in La$_{1.875}$Ba$_{0.125}$CuO$_4$
- Author
-
Chen, X. M., Thampy, V., Mazzoli, C., Barbour, A. M., Miao, H., Gu, G. D., Cao, Y., Tranquada, J. M., Dean, M. P. M., and Wilkins, S. B.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science ,Condensed Matter - Strongly Correlated Electrons - Abstract
The occurrence of charge-density-wave (CDW) order in underdoped cuprates is now well established, although the precise nature of the CDW and its relationship with superconductivity is not. Theoretical proposals include contrasting ideas such as that pairing may be driven by CDW fluctuations or that static CDWs may intertwine with a spatially-modulated superconducting wave function. We test the dynamics of CDW order in La$_{1.825}$Ba$_{0.125}$CuO$_4$ by using x-ray photon correlation spectroscopy (XPCS) at the CDW wave vector, detected resonantly at the Cu $L_3$-edge. We find that the CDW domains are strikingly static, with no evidence of significant fluctuations up to 2\,\nicefrac{3}{4} hours. We discuss the implications of these results for some of the competing theories., Comment: Accepted for publication in Physical Review Letters; 6 pages, 4 figures; + supplementary
- Published
- 2016
- Full Text
- View/download PDF
45. Thermal evolution of antiferromagnetic correlations and tetrahedral bond angles in superconducting FeTe$_{1-x}$Se$_x$
- Author
-
Xu, Zhijun, Schneeloch, J. A., Wen, Jinsheng, Bozin, E. S., Granroth, G. E., Winn, B. L., Feygenson, M., Birgeneau, R. J., Gu, Genda, Zaliznyak, I. A., Tranquada, J. M., and Xu, Guangyong
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Strongly Correlated Electrons - Abstract
It has recently been demonstrated that dynamical magnetic correlations measured by neutron scattering in iron chalcogenides can be described with models of short-range correlations characterized by particular {choices of four-spin plaquettes, where the appropriate choice changes as the} parent material is doped towards superconductivity. Here we apply such models to describe measured maps of magnetic scattering as a function of two-dimensional wave vectors obtained for optimally superconducting crystals of FeTe$_{1-x}$Se$_x$. We show that the characteristic antiferromagnetic wave vector evolves from that of the bicollinear structure found in underdoped chalcogenides (at high temperature) to that associated with the stripe structure of antiferromagnetic iron arsenides (at low temperature); {these can both be described with the same local plaquette, but with different inter-plaquette correlations}. While the magnitude of the low-energy magnetic spectral weight is substantial at all temperatures, it actually weakens somewhat at low temperature, where the charge carriers become more itinerant. The observed change in spin correlations is correlated with the dramatic drop in the electronic scattering rate and the growth of the bulk nematic response on cooling. Finally, we also present powder neutron diffraction results for lattice parameters in FeTe$_{1-x}$Se$_x$ indicating that the tetrahedral bond angle tends to increase towards the ideal value on cooling, in agreement with the increased screening of the crystal field by more itinerant electrons and the correspondingly smaller splitting of the Fe $3d$ orbitals.
- Published
- 2015
- Full Text
- View/download PDF
46. Charge-screening role of $c$-axis atomic displacements in YBa$_2$Cu$_3$O$_{6+x}$ and related superconductors
- Author
-
Bozin, E. S., Huq, A., Shen, Bing, Claus, H., Kwok, W. K., and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity - Abstract
The importance of charge reservoir layers for supplying holes to the CuO$_2$ planes of cuprate superconductors has long been recognized. Less attention has been paid to the screening of the charge transfer by the intervening ionic layers. We address this issue in the case of YBa$_2$Cu$_3$O$_{6+x}$, where CuO chains supply the holes for the planes. We present a simple dielectric-screening model that gives a linear correlation between the relative displacements of ions along the $c$ axis, determined by neutron powder diffraction, and the hole density of the planes. Applying this model to the temperature dependent shifts of ions along the $c$ axis, we infer a charge transfer of 5-10% of the hole density from the planes to the chains on warming from the superconducting transition to room temperature. Given the significant coupling of $c$-axis displacements to the average charge density, we point out the relevance of local displacements for screening charge modulations and note recent evidence for dynamic screening of in-plane quasiparticles. This line of argument leads us to a simple model for atomic displacements and charge modulation that is consistent with images from scanning-tunneling microscopy for underdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$., Comment: 12 pages, 10 figures; final version, accepted for publication in Phys. Rev. B
- Published
- 2015
- Full Text
- View/download PDF
47. Designing the stripe-ordered cuprate phase diagram through uniaxial-stress
- Author
-
Guguchia, Z; https://orcid.org/0000-0002-0764-7574, Das, D; https://orcid.org/0000-0001-5453-0195, Simutis, G; https://orcid.org/0000-0002-2697-2938, Adachi, T; https://orcid.org/0000-0002-9223-8483, Küspert, J; https://orcid.org/0000-0002-2905-9992, Kitajima, N, Elender, M, Grinenko, V, Ivashko, O; https://orcid.org/0000-0002-4869-8175, Zimmermann, M v; https://orcid.org/0000-0002-9320-6846, Müller, M; https://orcid.org/0000-0002-0299-952X, Mielke, C, Hotz, F; https://orcid.org/0000-0002-6874-0203, Mudry, C; https://orcid.org/0000-0003-4074-6758, Baines, C; https://orcid.org/0000-0003-2354-4134, Bartkowiak, M; https://orcid.org/0000-0001-9866-2165, Shiroka, T; https://orcid.org/0000-0001-8624-2649, Koike, Y, Amato, A, Hicks, C W; https://orcid.org/0000-0002-1736-1406, Gu, G D, Tranquada, J M; https://orcid.org/0000-0003-4984-8857, Klauss, H -H, Chang, J J; https://orcid.org/0000-0002-4655-1516, Janoschek, M, Luetkens, H; https://orcid.org/0000-0002-5842-9788, Guguchia, Z; https://orcid.org/0000-0002-0764-7574, Das, D; https://orcid.org/0000-0001-5453-0195, Simutis, G; https://orcid.org/0000-0002-2697-2938, Adachi, T; https://orcid.org/0000-0002-9223-8483, Küspert, J; https://orcid.org/0000-0002-2905-9992, Kitajima, N, Elender, M, Grinenko, V, Ivashko, O; https://orcid.org/0000-0002-4869-8175, Zimmermann, M v; https://orcid.org/0000-0002-9320-6846, Müller, M; https://orcid.org/0000-0002-0299-952X, Mielke, C, Hotz, F; https://orcid.org/0000-0002-6874-0203, Mudry, C; https://orcid.org/0000-0003-4074-6758, Baines, C; https://orcid.org/0000-0003-2354-4134, Bartkowiak, M; https://orcid.org/0000-0001-9866-2165, Shiroka, T; https://orcid.org/0000-0001-8624-2649, Koike, Y, Amato, A, Hicks, C W; https://orcid.org/0000-0002-1736-1406, Gu, G D, Tranquada, J M; https://orcid.org/0000-0003-4984-8857, Klauss, H -H, Chang, J J; https://orcid.org/0000-0002-4655-1516, Janoschek, M, and Luetkens, H; https://orcid.org/0000-0002-5842-9788
- Abstract
The ability to efficiently control charge and spin in the cuprate high-temperature superconductors is crucial for fundamental research and underpins technological development. Here, we explore the tunability of magnetism, superconductivity, and crystal structure in the stripe phase of the cuprate La[Formula: see text]Ba[Formula: see text]CuO[Formula: see text], with [Formula: see text] = 0.115 and 0.135, by employing temperature-dependent (down to 400 mK) muon-spin rotation and AC susceptibility, as well as X-ray scattering experiments under compressive uniaxial stress in the CuO[Formula: see text] plane. A sixfold increase of the three-dimensional (3D) superconducting critical temperature [Formula: see text] and a full recovery of the 3D phase coherence is observed in both samples with the application of extremely low uniaxial stress of [Formula: see text]0.1 GPa. This finding demonstrates the removal of the well-known 1/8-anomaly of cuprates by uniaxial stress. On the other hand, the spin-stripe order temperature as well as the magnetic fraction at 400 mK show only a modest decrease under stress. Moreover, the onset temperatures of 3D superconductivity and spin-stripe order are very similar in the large stress regime. However, strain produces an inhomogeneous suppression of the spin-stripe order at elevated temperatures. Namely, a substantial decrease of the magnetic volume fraction and a full suppression of the low-temperature tetragonal structure is found under stress, which is a necessary condition for the development of the 3D superconducting phase with optimal [Formula: see text]. Our results evidence a remarkable cooperation between the long-range static spin-stripe order and the underlying crystalline order with the three-dimensional fully coherent superconductivity. Overall, these results suggest that the stripe- and the SC order may have a common physical mechanism.
- Published
- 2024
48. Neutron scattering study of spin ordering and stripe pinning in superconducting La$_{1.93}$Sr$_{0.07}$CuO$_4$
- Author
-
Jacobsen, H., Zaliznyak, I. A., Savici, A. T., Winn, B. L., Chang, S., Huecker, M., Gu, G. D., and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity - Abstract
The relationships among charge order, spin fluctuations, and superconductivity in underdoped cuprates remain controversial. We use neutron scattering techniques to study these phenomena in La$_{1.93}$Sr$_{0.07}$CuO$_4$, a superconductor with a transition temperature of $T_c = 20$~K. At $T\ll T_c$, we find incommensurate spin fluctuations with a quasielastic energy spectrum and no sign of a gap within the energy range from 0.2 to 15 meV. A weak elastic magnetic component grows below $\sim10$~K, consistent with results from local probes. Regarding the atomic lattice, we have discovered unexpectedly strong fluctuations of the CuO$_6$ octahedra about Cu-O bonds, which are associated with inequivalent O sites within the CuO$_2$ planes. Furthermore, we observed a weak elastic $(3\bar{3}0)$ superlattice peak that implies a reduced lattice symmetry. The presence of inequivalent O sites rationalizes various pieces of evidence for charge stripe order in underdoped \lsco. The coexistence of superconductivity with quasi-static spin-stripe order suggests the presence of intertwined orders; however, the rotation of the stripe orientation away from the Cu-O bonds might be connected with evidence for a finite gap at the nodal points of the superconducting gap function., Comment: 13 pages, 11 figures; accepted version
- Published
- 2015
- Full Text
- View/download PDF
49. Dependence of superconductivity in CuxBi2Se3 on quenching conditions
- Author
-
Schneeloch, J. A., Zhong, R. D., Xu, Z. J., Gu, G. D., and Tranquada, J. M.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science - Abstract
Topological superconductivity, implying gapless protected surface states, has recently been proposed to exist in the compound CuxBi2Se3. Unfortunately, low diamagnetic shielding fractions and considerable inhomogeneity have been reported in this compound. In an attempt to understand and improve on the finite superconducting volume fractions, we have investigated the effects of various growth and post-annealing conditions. With a melt-growth (MG) method, diamagnetic shielding fractions of up to 56% in Cu0.3Bi2Se3 have been obtained, the highest value reported for this method. We investigate the efficacy of various quenching and annealing conditions, finding that quenching from temperatures above 560C is essential for superconductivity, whereas quenching from lower temperatures or not quenching at all is detrimental. A modified floating zone (FZ) method yielded large single crystals but little superconductivity. Even after annealing and quenching, FZ-grown samples had much less chance of being superconducting than MG-grown samples. From the low shielding fractions in FZ-grown samples and the quenching dependence, we suggest that a metastable secondary phase having a small volume fraction in most of the samples may be responsible for the superconductivity., Comment: 8 pages, 2 figures; to appear in Physical Review B
- Published
- 2015
- Full Text
- View/download PDF
50. Surface-state-dominated transport in crystals of the topological crystalline insulator In-doped Pb$_{1-x}$Sn$_x$Te
- Author
-
Zhong, Ruidan, He, Xugang, Schneeloch, John A., Zhang, Cheng, Liu, Tiansheng, Pletikosic, Ivo, Li, Qiang, Ku, Wei, Valla, Tonica, Tranquada, J. M., and Gu, Genda
- Subjects
Condensed Matter - Materials Science - Abstract
Three-dimensional topological insulators and topological crystalline insulators represent new quantum states of matter, which are predicted to have insulating bulk states and spin-momentum-locked gapless surface states. Experimentally, it has proven difficult to achieve the high bulk resistivity that would allow surface states to dominate the transport properties over a substantial temperature range. Here we report a series of indium-doped Pb$_{1-x}$Sn$_x$Te compounds that manifest huge bulk resistivities together with strong evidence of topological surface states, based on thickness-dependent transport studies and magnetoresistance measurements. For these bulk-insulating materials, the surface states determine the resistivity for temperatures approaching 30 K., Comment: 5 pages, 3 figures
- Published
- 2015
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.