Study of the Gr\"{u}neisen Parameters at a Field-induced Quantum Critical Point in NiCl2-SC(NH2)2

ORAL

Abstract

NiCl$_{2}$-SC(NH$_{2})_{2}$, also known as DTN, is a quantum paramagnet, where the Ni$^{2+}$ single ion anisotropy $D$ = 8.9K opens an energy gap between the $S_{z}$ = 0 ground state and the $S_{z}=\pm $1 exited state. In this material an XY-antiferromagnetic ordered state is induced at low temperatures by applying magnetic fields between $H_{c1} \quad \approx $ 2T and $H_{c2}$ = 10.5T. At the phase boundaries critical exponents consistent with Bose-Einstein condensation of magnons are found. Here we present investigations of quantum criticality close to $H_{c1}$ by thermal expansion, magnetization and specific heat measurements. Our data reveal a divergency for T$\to $ 0 of the thermal and magnetic Gr\"{u}neisen parameters as expected for a quantum critical point of a diluted Bose gas.

*Part of this work was carried out at the MPI for Chemical Physics of Solids in Dresden, Germany.

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Authors

  • Franziska Weickert

    • Los Alamos National Laboratory, MPA-CMMS, Los Alamos, NM, 87545, USA

  • Robert Kuechler

    • Max Planck Institute for Chemical Physics of Solids, Dresden 01087, Germany

  • Alexander Steppke

    • Max Planck Institute for Chemical Physics of Solids, Dresden 01087, Germany

  • Luis Pedrero Ojeda

    • Max Planck Institute for Chemical Physics of Solids, Dresden 01087, Germany

  • Michael Nicklas

    • Max Planck Institute for Chemical Physics of Solids, Dresden 01087, Germany

  • Manuel Brando

    • Max Planck Institute for Chemical Physics of Solids, Dresden 01087, Germany

  • Frank Steglich

    • Max Planck Institute for Chemical Physics of Solids, Dresden 01087, Germany

  • Vivien Zapf

    • Los Alamos National Laboratory, MPA-CMMS, Los Alamos, NM, 87545, USA

  • Marcelo Jaime

    • Los Alamos National Laboratory, MPA-CMMS, Los Alamos, NM, 87545, USA

  • A. Paduan-Filho

    • Univ. of Sao Paulo, Sao Paulo, Brazil