Low temperature thermodynamics of triangular lattice quantum spin liquid candidate TlYbS
arXiv:2609.11881
Abstract
Geometrically frustrated triangular-lattice antiferromagnets exhibit a delicate competition between magnetic order and quantum spin liquid (QSL) behavior, with the Yb-based delafossite family Yb providing a structurally clean platform for exploring this physics. Here, we report a comprehensive study of single-crystal TlYbS using DC magnetization, AC susceptibility, electron spin resonance (ESR), and specific heat measurements extending from room temperature to the millikelvin regime. Single-crystal X-ray diffraction confirms a trigonal structure comprising well-separated triangular layers of Yb ions with no detectable site disorder. At zero field, a weak thermodynamic anomaly is observed near mK, which may indicate the onset of a weakly ordered state similar to that reported in KYbSe. Below mK, the zero-field magnetic specific heat follows , close to a quadratic temperature dependence, in contrast to the linear temperature dependence reported for the sister compound TlYbSe, which has been described in terms of the interplay between spinons and thermally excited gauge-flux excitations. Magnetization and ESR measurements establish pronounced easy-plane magnetic anisotropy, with . The anomaly near mK exhibits a strongly anisotropic response to magnetic field. For , it remains visible up to approximately T and continuously evolves toward a field-induced ordered phase above approximately T, followed by a sequence of field-induced phases that includes a magnetization plateau between approximately and T and full polarization near T. In contrast, for , the anomaly weakens and is suppressed near T, consistent with the recently reported confinement--deconfinement transition from an ordered state to a field-induced QSL.
11 Pages, 5 figures