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Low-temperature neutron diffraction experiments at P = 8 GPa have been conducted to investigate the magnetic structures of metallic Holmium at high pressures by employing a long d-spacing highflux diffractometer and a Paris-Edinburgh press cell inside a cryostat. We find that at P = 8 GPa and T = 5 K, no nuclear symmetry change is observed, keeping therefore the hexagonal closed packed (hcp) symmetry at high pressure. Our neutron diffraction data confirm that the ferromagnetic state does not exist. The magnetic structure corresponding to the helimagnetic order, which survives down to 5 K, is fully described by the magnetic superspace group formalism. These results are consistent with those previously published using magnetization experiments.

Through advanced experimental techniques on Formula Presented single crystals, we derive a pressure-temperature phase diagram. We find that Formula Presented increases to Formula Presented K with pressure up to Formula Presented GPa followed by a decrease to Formula Presented K at 21.2 GPa. The experimental results are reproduced by theoretical calculations based on density functional theory where electron-electron interactions are treated by a static on-site Hubbard Formula Presented on Cr Formula Presented orbitals. The origin of the pressure-induced reduction of the ordering temperature is associated with a decrease in the calculated bond angle, from Formula Presented at ambient pressure to Formula Presented at 25 GPa. Above 22 GPa, experiment and theory jointly point to the idea that the ferromagnetically ordered state is destroyed, giving rise first to a complex, unknown magnetic configuration, and at sufficiently high pressures a pure antiferromagnetic configuration. This sequence of transitions in the magnetism is accompanied by a well-detected pressure-induced semiconductor-to-metal phase transition that is revealed by both high-pressure resistivity measurements and ab initio theory. ©2022 American Physical Society. A.G. and M.A.-H. acknowledge financial support from the Carl Tryggers Foundation and the Swedish Research Council (VR) under Project No. 2018-05393. Support by the P220 291 program of the Government of Russia through Project No. 292 075-15-2021-604 and President of Russia through Project No. NSh-2394.2022.1.5 is acknowledged. G.H. and M.K. acknowledge support from the Czech Science Foundation (Project No. 20-08633X). J.V. acknowledges the support of Czech Research Infrastructures MGML (Project No. LM2018096). O.E. acknowledges financial support from the Knut and Alice Wallenberg Foundation, eSSENCE, SNIC, the VR, the Foundation for Strategic Research (SSF), and the ERC (Synergy Grant FASTCORR, Project No. 854843). Y.K. acknowledges financial support from the VR under Project No. 2019-03569. The computations and data handling were enabled by resources provided by the Swedish National Infrastructure for Computing (SNIC), partially funded by the Swedish Research Council through Grant Agreement No. 2018-05973.

The intermetallic compound Fe1−xCoxSi has a helical magnetic order for 0.05

We investigated transport and magnetic properties of NdFeAsO$_{0.9}$F$_{0.1}$ single crystal under hydrostatic pressures up to 50\,GPa. The ambient pressure superconductivity at $T_{c} \sim$ 45.4\,K is fully suppressed at $P_{c} \sim$ 21 GPa. Upon further increase of the pressure, the ferromagnetism associated with the order of rare-earth subsystem is induced at the border of superconductivity. Our finding is supported by the hysteresis in the magnetization $M$($H$) loops and the strong increase in the field cooled data, $M$($T$), toward low temperatures. We also show that the temperature evolution of the electrical resistivity as a function of pressure is consistent with a crossover from a Fermi-liquid to non-Fermi-liquid to Fermi-liquid. These results give access to the high-pressure side of the superconducting phase diagram in 1111 type of materials., 6 pages, 4 figures

The chiral magnet CrNb3S6 with its solitonic objects has novel magnetic and transport properties, in which the spin-orbit coupling (SOC) plays a central role. Aiming to address the possible existence of orbital moments driven by SOC, we perform soft x-ray magnetic circular dichroism spectroscopy at the Cr L2,3 edges with in-plane magnetization. The dichroic signals provide direct experimental evidence that the Cr orbital magnetic moment is not quenched and is coupled antiparallel to the spin counterpart. Application of the orbital sum rule reveals that the magnitude of the Cr orbital moment is about 1% of the total magnetization. These findings are consistent with the first-principles electronic structure calculations that utilize the Cr 2p core radial function to define the Cr local 3d quantities. The distinct roles of the atomic SOC among the Cr 3d and Nb 4d states are discussed.

We synthesized magnetically frustrated DyMn2O5 nanoparticles in pores of mesoporous silica, with particle sizes ranging from 7 to 20 nm, and investigated their magnetostructural correlation. We found that the lattice constants of the DyMn2O5 nanoparticles deviated from those of the bulk crystal below ∼12 nm and their crystallographic structures at the unit cell level were distorted. The size dependences of the blocking temperature and coercive field drastically change at ∼12 nm. In addition, the Weiss temperature depends strongly on particle size, and its sign changes at ∼12 nm. It is considered that such features can be realized owing to the distortion caused by the ligand atoms at the surface. The orbital structures of the magnetic sites are easily modified due to the distortion of the ligand ions at the surface, so that the correlation between the crystal structure and magnetic properties can be enhanced. Moreover, magnetization of the nanoparticle results in quasi-superparamagnetic behavior. Monte Carlo calculation of the nanoparticles indicates that such a feature is realized due to the quasi-free spins induced at the surface by magnetic frustration.

While the layered 122 iron arsenide superconductors are highly anisotropic, unconventional, and exhibit several forms of electronic orders that coexist or compete with superconductivity in different regions of their phase diagrams, we find in the absence of iron in the structure that the superconducting characteristics of the end member BaPd2As2 are surprisingly conventional. Here we report on complementary measurements of specific heat, magnetic susceptibility, resistivity measurements, Andreev spectroscopy, and synchrotron high pressure x-ray diffraction measurements supplemented with theoretical calculations for BaPd2As2. Its superconducting properties are completely isotropic as demonstrated by the critical fields, which do not depend on the direction of the applied field. Under the application of high pressure, Tc is linearly suppressed, which is the typical behavior of classical phonon-mediated superconductors with some additional effect of a pressure-induced decrease in the electronic density of states and the electron-phonon coupling parameters. Structural changes in the layered BaPd2As2 have been studied by means of angle-dispersive diffraction in a diamond-anvil cell. At 12 GPa and 24.2 GPa we observed pressure induced lattice distortions manifesting as the discontinuity and, hence discontinuity in the Birch-Murnaghan equation of state. The bulk modulus is B0=40(6) GPa below 12 GPa and B0=142(3) GPa below 27.2 GPa. © 2018 American Physical Society. We are grateful to the support of the DFG, Deutsche Forschungsgemeinschaft through MO 3014/1-1. A.S. and A.U. are grateful to the support of the RSCF Grant No. 16-12-10507, V.P. acknowledges support by the RSCF Grant No. 16-42-01100. HPCAT operations are supported by DOE-NNSA under Award No. DE-NA0001974 and DOE-BES under Award No. DE-FG02-99ER45775, with partial instrumentation funding by NSF. A.P.S. is supported by DOE-BES, under Contract No. DE-AC02-06CH11357. Y.-W.F. acknowledges the computing center of ECNU and Bridges system of Extreme Science and Engineering Discovery Environment (XSEDE) for providing the computational resources. This work has been supported by Ministry of Education and Science of Russia through NUST “MISiS” Grant No. K2-2017-084 and by the Act 211 of the Government of Russia, contract 02.A03.21.0004.

Objective To establish early postnatal norms for the main measurements of the soft-tissue orbits for the Slavic Bulgarian population (9 million), we measured intercanthal (en-en) and biocular width (ex-ex) and length of the palpebral fissures (ex-en) in a representative sample of newborns less than six days old. Method Eye measurements were taken with a sliding caliper from randomly chosen subjects by the senior author using standard anthropometric methods. Findings were compared to those published for other Caucasian ethnic groups of infants (Germans and two groups of North American Caucasians). Results The mean values of all three soft orbital measurements were greater in newborn Bulgarian boys than girls. Measurements of Bulgarian intercanthal width (en-en) were greater in both sexes but those of biocular width (ex-ex) and palpebral fissure length (ex-en) were less than those that have been reported for North American Caucasian infants. Bulgarian intercanthal and biocular measurements were wider than German babies in both sexes. Differences, although small, were statistically highly significant but greatly influenced by differing sample sizes and subject age among the four Caucasian populations. Conclusion Anthropometric differences between ethnic groups of Caucasians already exist shortly after birth. Knowledge of the soft orbital data in early stages of the postnatal development in healthy populations is essential for determination in individuals of deviations from normal data. These Bulgarian norms can be helpful in anthropometric studies of the ethnically mixed Caucasian populations of North America.

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY)., Room temperature Fe and Co K-edge x-ray magnetic circular dichroism, synchrotron x-ray powder diffraction, and magnetization measurements were carried out to investigate the stability of the ferrimagnetic ground state in CoxFe3-xO4 (x=0, 1, 1.5, and 2) ferrites under pressure up to about 30 GPa using diamond anvil cells. The x-ray magnetic circular dichroism at the Fe K-edge is observed to decrease continuously up to the highest reached pressure by ∼50% in Fe3O4 (at 25 GPa) and by ∼70% in Co1.5Fe1.5O4 (at 16 GPa) and Co2FeO4 (at 21 GPa). In CoFe2O 4, the suppression by ∼80% of the x-ray magnetic circular dichroic signal occurs simultaneously at both Fe and Co K-edges between 24 and 27 GPa. However, a continuous decrease of the dichroic signal with pressure is only observed at the Co K-edge, whereas the Fe K-edge dichroic intensity drops drastically. The synchrotron x-ray powder diffraction measurements indicate the occurrence of structural phase transitions at critical pressures in coincidence with the suppression of ferrimagnetism. In CoFe2O4, bulk magnetization measurements up to 26 GPa confirm the disappearance of ferrimagnetism and indicate an almost linear dependence of the magnetization with the magnetic field in the high pressure phase. We thus conclude that high-pressure CoFe2O4 is either paramagnetic or antiferromagnetic. © 2013 American Physical Society., This research was financed by the Spanish MICINN (Project No. MAT2012-38213-C02-01) and DGA (CAMRADS).

We construct the phase diagram of the chiral magnet Cr1/3NbS2 in a dc magnetic field (Hdc) using ac magnetic susceptibility measurements. At Hdc = 0, the ac response at the transition from the helical magnetic (HM) state to the paramagnetic (PM) state consists of a giant third-order harmonic component (M3ω) and a first-order harmonic component (M1ω). By applying Hdc perpendicular to the c axis, the HM state is transformed to the chiral soliton lattice (CSL) state, which is a superlattice tuned by Hdc. The above giant M3ω is markedly suppressed at small Hdc. The CSL state is found to consist of CSL-1, with dominant helical texture and a poor ferromagnetic array, and CSL-2, with a large ferromagnetic array. The transition between CSL-1 and the PM state causes a linear magnetic response, the dominant component of which is the in-phase M1ω. With increasing temperature, CSL-2 is transformed into the forced ferromagnetic (FFM) state, and ultimately the PM state is reached. The transition between CSL-2 and the FFM state consists of a large M3ω and large out-of-phase M1ω as well as in-phase M1ω. The transition between the FMM and PM states also yields a linear magnetic response, like the CSL-1–PM-state transition. Five typical magnetic dynamics in the transitions among the HMstate, CSL-1, CSL-2, FFM state, and PM state were identified according to the equivalent dynamical motion equation of a nonlinear spring model.

Resumen del trabajo presentado a la 19th International Conference on Magnetism celebrada en Korea del 8 al 13 de julio de 2012., We present structural and magnetic studies performed in ferrimagnetic and antiferromagnetic nanoparticles. We focus our attention on the antiferromagnetic ferritin and cobalt oxide and on the ferrimagnetic maghemite. High-field studies in ferritin reveal that the temperature dependence of the antiferromagnetic susceptibility decreases with temperature when correctly determined from high-field data. High-field hysteresis loops also show that coercivity and loop-shifts are a function of the maximum field, which can be understood in the frame of coherent rotation models considering a field-dependent anisotropy energy. Neutron diffraction is particularly effective in the study of structural and magnetic coherence sizes of antiferromagnetic nanoparticles. In the case of cobalt oxide, we found that the difference between both sizes is consistent with a core-shell model where the shell is structurally ordered but magnetically disordered with a thickness of ~2 nm. This core shell model was also successfully applied to a series of maghemite nanoparticles, based on small-angle X-ray scattering and magnetization results, yielding, in this case, a magnetically disordered shell with about 1nm. Surface and core contribution to anisotropy energy in maghemite can be elegantly separated by using pressure, since the core/shell volume ratio changes with pressure inducing a change in the average anisotropy energy.

A prospective randomised multicentre clinical study was undertaken for 2 years and 3 months from November 1982, with the aim of examining the significance of using a combination of ftorafur (FT) and tamoxifen (TAM) for post-operative adjuvant therapy of breast cancer. Patients had either stage II or stage IIIa disease, were age 75 or below and had undergone radical mastectomy. Patients were divided into two groups and received one of the following treatment protocols: treatment A, intravenous administration of doxorubicin (DOX), 20 mg on the day of surgery and 10 mg the next day, followed by oral FT 50 mg day-1 for 2 years from the 14th day; treatment B, the same pattern of DOX administration for the first 2 days, followed by a combined therapy of FT and TAM 20 mg day-1 for 2 years. The number of patients was 546 (treatment A 274 and treatment B 272), of whom 34 (6%) were ineligible. The remaining 512 patients (treatment A 254 and treatment B 258) were followed up for 5 years for analysis. Significantly higher 5 year disease-free rate and 5 year survival rates were observed with treatment B compared with treatment A. When seen in terms of background factors, node-positive patients appeared to derive more benefit from tamoxifen than node-negative patients, but the oestrogen receptor-negative and premenopausal subgroups appeared to derive about the same benefit as those who were oestrogen receptor positive and post-menopausal. Indeed, survival in the premenopausal group was significantly better with tamoxifen (P = 0.04). No increase in side-effects was seen by combining TAM with FT. The study results demonstrate that concomitant administration of FT and TAM is better than FT alone for post-operative adjuvant therapy for breast cancer.

We perform structural analysis experiments on the chiral magnet Cr1∕3NbS2, in which Cr3+ ions are inserted between hexagonal NbS2 layers. The noncentrosymmetrical nature of the inserted Cr3+ appears as a distorted CrS6 octahedron. Under the application of hydrostatic pressure, the lattice shrinks significantly along the c-axis rather than the a-axis. However, at a pressure P of approximately 3–4 GPa, a kink in the rate of decrease in the lattice parameters is observed, and the slight movement of a Nb atom along the c-axis brings about a decrease in the distortion of the CrS6 octahedron. This structural change qualitatively suggests a decrease in the strength of the Dzyaloshinskii-Moriya (D-M) interaction. Under hydrostatic pressure, the magnetic ordering temperature TC decreases, and dTC/dP exhibits a slight change at around 3 GPa. A series of experiments indicates that the change in the structural symmetry of the CrS6 octahedron influences the exchange network between Cr3+ ions as well as the D-M interaction.

We have measured the specific heat of an S=1/2 antiferromagnetic alternating Heisenberg chain pentafulorophenyl nitronyl nitroxide under magnetic fields up to H>H_C2. This compound has the field-induced magnetic ordered (FIMO) phase between H_C1 and H_C2. Characteristic behaviors are observed depending on the magnetic field up to above H_C2 outside of the H-T boundary for the FIMO. Temperature and field dependence of the specific heat are qualitatively in good agreement with the theoretical calculation on an S=1/2 two-leg ladder. [Wang et al. Phys. Rev. Lett 84 5399 (2000)] This agreement suggests that the observed behaviors are related with the low-energy excitation in the Tomonaga-Luttinger liquid., 4pages, 4figures, replaced with revised version accepted to Physical Review Letters

The pressure effects on an S=1/2 Heisenberg two-leg ladder antiferromagnet (H2LLAF) Cu2(C5H12N2)2Cl4 have been investigated through magnetic and thermal measurements under pressures up to 10 kbar. The exchange interactions along the rung and leg hardly change under pressures, but the pressurization induces paramagnetic spins and magnetic order. This magnetic order is a pressure-induced one observed in a quantum spin system with an energy gap. The amount of induced paramagnetic spins increases almost in accordance with the square of pressure. The magnetic field dependence of the pressure-induced Schottky-type heat capacity suggests that the induced paramagnetic spins are not completely free, but weakly correlate with the H2LLAF system. A magnetic anomaly of the heat capacity has been observed around 2.6 K for P>~8.5 kbar, where more than 20% of the paramagnetic spins are induced. This anomaly is considered to be intrinsic to the magnetic order of the H2LLAF system, which seems to be triggered by the modulation of the staggered moment due to local defects. Even below the magnetic ordering temperature, the paramagnetic spins coexit with the magnetic order of the H2LLAF system. These pressure effects are similar to the impurity effects in another typical S=1/2 H2LLAF SrCu2O3 doped with nonmagnetic Zn2+ ions.

We study low-temperature properties of Pr1−xLaxPb3 with the ground state of a non-Kramers Γ3 for 0≦x≦0.8. From the concentration dependence of the specific heat, quadrupolar ordering is expected to occur only up to x∼0.02. For a wide range of La concentrations where the ordering is absent, the specific heat shows a T linear variation, which is in an excellent agreement with the result obtained by the model for amorphous materials with a random configuration of a two-level system. Impurity effects on quadrupolar moments will be discussed.