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13 results on '"Aczel, A.A."'

7. Muon spin rotation/relaxation measurements of the non-centrosymmetric superconductor Mg10Ir19B16

Author

Aczel, A.A., Williams, T.J., Goko, T., Carlo, J. P., Yu, W., Uemura, Y.J., Klimczuk, T., Thompson, J. D., Cava, R.J., and Luke, G. M.

Subjects
Superconductivity (cond-mat.supr-con), Condensed Matter - Strongly Correlated Electrons, Strongly Correlated Electrons (cond-mat.str-el), Condensed Matter - Superconductivity, FOS: Physical sciences
Abstract

We have searched for time-reversal symmetry breaking fields in the non-centrosymmetric superconductor Mg$_{10}$Ir$_{19}$B$_{16}$ via muon spin relaxation in zero applied field, and we measured the temperature dependence of the superfluid density by muon spin rotation in transverse field to investigate the superconducting pairing symmetry in two polycrystalline samples of signficantly different purities. In the high purity sample, we detected no time-reversal symmetry breaking fields greater than 0.05 G. The superfluid density was also found to be exponentially-flat as T$\to $0, and so can be fit to a single-gap BCS model. In contrast, the lower purity sample showed an increase in the zero-field $\mu$SR relaxation rate below T$_c$ corresponding to a characteristic field strength of 0.6 G. While the temperature-dependence of the superfluid density was also found to be consistent with a single-gap BCS model, the magnitude as T$\to $0 was found to be much lower for a given applied field than in the case of the high purity sample. These findings suggest that the dominant pairing symmetry in high quality Mg$_{10}$Ir$_{19}$B$_{16}$ samples corresponds to the spin-singlet channel, while sample quality drastically affects the superconducting properties of this system., Comment: 6 pages, 5 figures, revised version resubmitted to PRB

Published
2010
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8. Bose-Einstein condensation of triplons in Ba3Cr2O8

Author

Aczel, A.A., Kohama, Yoshimitsu, Jaime, M., Ninios, K., Chan, Ho Bun, Balicas, L., Dabkowska, H.A., Luke, G.M., Aczel, A.A., Kohama, Yoshimitsu, Jaime, M., Ninios, K., Chan, Ho Bun, Balicas, L., Dabkowska, H.A., and Luke, G.M.

Abstract

By performing heat-capacity, magnetocaloric effect, torque magnetometry, and force magnetometry measurements up to 33 T, we have mapped out the T−H phase diagram of the S=1/2 spin dimer compound Ba3Cr2O8. We found evidence for field-induced magnetic order between Hc1=12.52(2) T and Hc2=23.60(5) T, with the maximum transition temperature Tc∼2.7 K at H∼18 T. The lower transition can likely be described by Bose-Einstein condensation of triplons theory, and this is consistent with the absence of any magnetization plateaus in our magnetic torque and force measurements. In contrast, our measurements uncovered magnetic field irreversibility associated with a symmetric specific heat versus temperature near Hc2 suggesting that the upper transition is first order.

Published
2009

10. Li(Zn,Mn)As as a new generation ferromagnet based on a I–II–V semiconductor

Author

Deng, Z., primary, Jin, C.Q., additional, Liu, Q.Q., additional, Wang, X.C., additional, Zhu, J.L., additional, Feng, S.M., additional, Chen, L.C., additional, Yu, R.C., additional, Arguello, C., additional, Goko, T., additional, Ning, Fanlong, additional, Zhang, Jinsong, additional, Wang, Yayu, additional, Aczel, A.A., additional, Munsie, T., additional, Williams, T.J., additional, Luke, G.M., additional, Kakeshita, T., additional, Uchida, S., additional, Higemoto, W., additional, Ito, T.U., additional, Gu, Bo, additional, Maekawa, S., additional, Morris, G.D., additional, and Uemura, Y.J., additional

Published
2011
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12. Magnetism in superconducting EuFe2As1.4P0.6 single crystals studied by local probes.

Author

Munevar, J., Micklitz, H., Alzamora, M., Argüello, C., Goko, T., Ning, F.L., Munsie, T., Williams, T.J., Aczel, A.A., Luke, G.M., Chen, G.F., Yu, W., Uemura, Y.J., and Baggio-Saitovitch, E.

Subjects
*MAGNETISM, *SUPERCONDUCTORS, *SINGLE crystals, *EUROPIUM compounds, *MUON spin rotation, *ANTIFERROMAGNETISM, *CRYSTALLOGRAPHY, *MAGNETIC moments
Abstract

Abstract: We have studied the magnetism in superconducting single crystals of EuFe2As1.4P0.6 by using the local probe techniques of zero-field muon spin rotation/relaxation and 151Eu/57Fe Mössbauer spectroscopy. All of these measurements reveal magnetic hyperfine fields below the magnetic ordering temperature of the Eu2+ moments. The analysis of the data shows that there is a coexistence of antiferromagnetism, resulting from Eu2+ moments ordered along the crystallographic c-axis, and superconductivity below 10K. We find indications for a change in the dynamics of the small Fe magnetic moments (~0.07 ) at that may be triggering the onset of superconductivity: below T ⁎ the Fe magnetic moments seem to be “frozen” within the ab-plane. [Copyright &y& Elsevier]

Published
2014
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13. Quadruple-layered perovskite (CuCl)Ca2NaNb4O13

Author

Kitada, A., Tsujimoto, Y., Yamamoto, T., Kobayashi, Y., Narumi, Y., Kindo, K., Aczel, A.A., Luke, G.M., Uemura, Y.J., Kiuchi, Y., Ueda, Y., Yoshimura, K., Ajiro, Y., and Kageyama, H.

Subjects
*PEROVSKITE, *MAGNETIC properties, *ION exchange (Chemistry), *CUPRIC chloride, *CALCIUM compounds, *RIETVELD refinement, *GROUP theory
Abstract

Abstract: We will present the synthesis, structure and magnetic properties of a new quadruple-layered perovskite (CuCl)Ca2NaNb4O13. Through a topotactic ion-exchange reaction with CuCl2, the precursor RbCa2NaNb4O13 presumably having an incoherent octahederal tliting changes into (CuCl)Ca2NaNb4O13 with a 2a p×2a p×2c p superstructure (tetragonal; a=7.73232(5)Å, c=39.2156(4)Å). The well-defined superstructure for the ion-exchanged product should be stabilized by the inserted CuCl4O2 octahedral layers that firmly connect with neighboring perovskite layers. Magnetic studies show the absence of long-range magnetic ordering down to 2K despite strong in-plane interactions. Aleksandrov′s group theory and Rietveld refinement of synchrotron X-ray diffraction data suggest the structure to be of I4/mmm space group with in-phase tilting along the a and b axes, a two-tilt system (++0). [Copyright &y& Elsevier]

Published
2012
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