AC magnetic susceptibility and heat capacity studies of the geometrically frustrated pyrochlores Ce<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub> and Ce<sub>2</sub>Hf<sub>2</sub>O<sub>7</sub>, as possible quantum spin liquids (QSL’s)

ORAL

Abstract

QSL’s are of great interest due to their unusual ground states; they do not exhibit spin freezing even at 0K, have no conventional order parameter associated with a broken symmetry, and can emerge in insulators containing localized spin degrees of freedom. In this work, single crystals of the low-spin geometrically frustrated 2D lattice pyrochlore compounds Ce2Zr2O7 and Ce2Hf2O, prepared by the floating zone method, were investigated for a possible QSL state. Measurements of AC magnetic susceptibility from 100 Hz to 10 kHz and heat capacity up to 9T were performed down to 100 mK. Despite a well-ordered pyrochlore crystal structure and strong magnetic interactions between Ce3+ ions in Ce2Zr2O7 and Ce2Hf2O7, no evidence for a transition to a long-range ordered state was found, possibly due to strong quantum fluctuations that prevent spin freezing and lead to QSL ground state. With increasing magnetic field, the Schottky heat capacity anomaly moves to higher temperatures, indicating the presence of a gap in the excitation spectrum, which increases monotonically with increasing field. The behavior for a two-level system with an excited level at energy Δ above the ground state is compared with the heat capacity data.

*Research supported by US DOE BES, NSF DM, cQMS (EPiQS - GBMF6402)

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Presenters

  • Kalyan Sasmal

    • University of California, San Diego
    • Department of Physics, University of California, San Diego, La Jolla, CA 92093
    • Department of Physics, University of California, San Diego
    • Department of Physics, University of California, San Diego, CA 92093, USA

Authors

  • Kalyan Sasmal

    • University of California, San Diego
    • Department of Physics, University of California, San Diego, La Jolla, CA 92093
    • Department of Physics, University of California, San Diego
    • Department of Physics, University of California, San Diego, CA 92093, USA

  • Manivannan Nallaiyan

    • Quantum Design Inc, San Diego, CA 92121, USA
    • Quantum Design Inc

  • Bin Gao

    • Rutgers University, New Brunswick
    • Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
    • Department of Physics and Astronomy, Rice University

  • David W Tam

    • Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
    • Department of Physics and Astronomy, Rice University

  • Tong Chen

    • Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
    • Department of Physics and Astronomy, Rice University

  • Sang-Wook Cheong

    • Rutgers University
    • Department of Physics and Astronomy, Rutgers University
    • Rutgers University, New Brunswick
    • Rutgers Center for Emergent Materials and Department of Physics & Astronomy, Rutgers University
    • Center for Quantum Materials Synthesis and Department of Physics and Astronomy, Rutgers, the State University of New Jersey
    • Department of Physics, Rutgers University
    • Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ
    • Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
    • Physics, Rutgers University
    • Physics and Astronomy, Rutgers University, New Brunswick
    • Department of Physics and Astronomy, Rutgers University, New Jersey
    • Rutgers University, Physics and Astronomy, and Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science
    • RCEM, Department of Physics and Astronomy, Rutgers U.
    • Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University
    • Department of Physics and Astronomy, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA, Rutgers Center for Emergent Materials

  • Stefano Spagna

    • Quantum Design Inc, San Diego, CA 92121, USA
    • Quantum Design Inc

  • Pengcheng Dai

    • Rice University
    • Department of Physics and Astronomy, Rice University
    • Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA

  • M Brian Maple

    • University of California, San Diego
    • Department of Physics, University of California, San Diego, La Jolla, CA 92093
    • Department of Physics, University of California, San Diego
    • UC San Diego
    • Physics, University of California, San Diego
    • Department of Physics, University of California, San Diego, CA 92093, USA
    • Physics, University of California, SanDiego