High-field resonant torsion magnetometry as a probe of CEF Interactions and exchange in frustrated triangular lattice CsYbSe₂

We probe magnetoanisotropy of the highly frustrated 2-dimensional triangular lattice antiferromagnet CsYbSe₂, using resonant torsion magnetometry in pulsed fields up to 60 T. In recent years, the family of 112 systems of the form ARQ₂ (A = Alkali, R = Rare Earth, Q = O, S, Se) has attracted much experimental and theoretical attention for its potential to realize a QSL with effective spin-1/2 rare-earth ions on the triangular lattice, a canonical geometry for frustrated magnetism. Our analysis of the high-field magnetotropic response of CsYbSe₂, across a wide range of temperatures, provides an unambiguous determination of the crystal-electric-field parameters as well as leading order exchange interactions in CsYbSe₂. In turn, this information is utilized to identify potential exotic spin states and to set clear boundaries for the applicability of existing spin models. We will also discuss possible experimental implications of QSLs for this family of rare-earth triangular lattice compounds.