Dresden 2020 – wissenschaftliches Programm
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TT 46.10: Poster
Mittwoch, 18. März 2020, 15:00–19:00, P2/2OG
Thermodynamic investigations of the quantum-spin-liquid candidate Ca10Cr7O28 — •Ulrich Tutsch1, Christian Thurn1, Christian Balz2,3,4, Bella Lake3,4, and Michael Lang1 — 1Physikalisches Institut, Goethe-Universität Frankfurt am Main, Germany — 2Neutron Scattering Division, Oak Ridge National Laboratory, Tennessee, USA — 3Helmholtz-Zentrum für Materialien und Energie, Berlin, Germany — 4Institut für Festkörperphysik, Technische Universität Berlin, Germany
A quantum-spin-liquid (QSL) is characterized by a coherent and highly entangled ground state without any long-range spin order. One strategy for the realization of such a state is the use of geometrical frustration, as, e.g., encountered in Ca10Cr7O28 with its distorted spin-1/2 kagome bilayer structure. Previous studies have failed to detect any sign of long-range magnetic order in this compound down to 19 mK, its spins staying entirely dynamic. Here, we present low-temperature (40 mK≤ T≤1.7 K) data of the specific heat C and the thermal expansion α for Ca10Cr7O28 at various magnetic fields B up to 12 T . No indications for a phase transition are observed. Instead, a kink-like structure is revealed around 0.5 K, resembling a crossover rather than a phase transition. Both quantities, C(T) and α(T), are significantly affected by already small magnetic fields (< 1 T) although a field of about 12 T is needed to open a gap in the magnetic excitation spectrum. These experimental findings support the quantum-spin-liquid hypothesis for Ca10Cr7O28 and promise interesting physics.
 J. Sonnenschein et al., Phys. Rev. B 100, 174428 (2019)