Specific heat measurements in the novel frustrated quantum magnets SrHo$_{2}$O$_{4}$ and SrDy$_{2}$O$_{4}$

ORAL

Abstract

We investigated the specific heat of the novel geometrically frustrated quantum magnets SrHo$_{2}$O$_{4}$ and SrDy$_{2}$O$_{4}$ to determine the nature of their ground states. We present a study of the magnetic field dependence of specific heat $C_p(T,H)$ measured in a dilution refrigerator between 0.1 K and 4 K and a PPMS between 2 and 50~K for magnetic fields $H$ between 0 and 9~T. We subtracted the phonon background $C_{\mathrm{ph}}$ by using a temperature dependent Debye temperature determined from measurements on the non-magnetic structural analogue SrLu$_2$O$_4$. After this subtraction, in SrHo$_2$O$_4$ we observed a broad anomaly in the magnetic specific heat $C_{\mathrm{mag}} = C_p - C_{\mathrm{ph}}$ centered at 0.5 K in zero field. At high fields, we found a broad peak centered at 0.35 K which decreases with rising magnetic field. SrDy$_2$O$_4$ in zero field has a broad anomaly at 1.2~K. The peak broadens with increasing $H$ and its amplitude decreases, and by 5~T it is completely suppressed. By 50~K, each ion in the Dy compound has recovered 21.5~J/mol~K of its spin entropy, which is comparable to the entire spin entropy of a free Dy ion of $R \cdot ln(2J+1)$, whereas we observe only 11.1~J/mol~K for SrHo$_2$O$_4$.

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Authors

  • Andrea Bianchi

    Dep. de physique, Universite de Montreal, Montreal, QC, Canada, Universite de Montreal, Canada, U. de Montreal, QC, Montreal, Canada, Universite de Montreal

  • Bobby Prevost

    U. de Montreal, QC, Montreal, Canada, Universite de Montreal

  • N. Kurita

    Los Alamos National Laboratory, LANL, Los Alamas, NM, USA, Los Alamos National Laboratory, Los Alamos, NM 87544, USA

  • F. Ronning

    Los Alamos National Laboratory, LANL, Los Alamas, NM, USA, Los Alamos National Laboratory, Los Alamos, NM 87544, USA

  • R. Movshovich

    Los Alamos National Laboratory, LANL, Los Alamas, NM, USA, Los Alamos National Laboratory, Los Alamos, NM 87544, USA

  • T. W. Klimczuk

    LANL, Los Alamas, NM, USA

  • M. Kenzelmann

    LDM, PSI, Villigen, Switzerland, ETHZ \& Paul Scherrer Institute, Switzerland, Paul Scherrer Institute

  • R. J. Cava

    Department of Chemistry, Princeton University, Dept. Chemistry, Princeton University, Princeton, NJ, USA, Princeton University, Princeton, NJ, USA