Field-induced magnetic phase transition driven by a ground-state level crossing in; <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">; <mml:msub>; <mml:mi>CsErSe</mml:mi>; <mml:mn>2</mml:mn>; </mml:msub>; </mml:math> | CU Experts

; We report a comprehensive study of the low-temperature magnetic properties of the insulating rare-earth triangular magnet; ; ; CsErSe; 2; ; ; . We uncover a field-induced level crossing at the crystal electric field ground state, which gives rise to a first-order phase transition as well as to distinctive magnetic properties. This crossing is identified by the accurate determination of the single-ion Hamiltonian, the reliability of which is substantially enhanced by field-dependent optical spectroscopy that directly tracks the Zeeman splittings of Kramers doublets. We also observe spontaneous antiferromagnetic ordering in; ; ; CsErSe; 2; ; ; below; ; ; ; T; N; ; ≈; 110; ; mK; ; ; and resolve the corresponding magnetic structure using elastic neutron scattering. We discuss how the rich magnetic behavior of; ; ; CsErSe; 2; ; ; arises from the interplay of nontrivial field-dependent single-ion physics and spontaneous ordering, and highlight the implications of these results for understanding magnetic phenomena across a wide range of insulating rare-earth magnets.;

Whitelock H; Scheie AO; McMaster M; Leahy IA; Xiang L; Ozerov M; Smirnov D; Choi ES; dela Cruz C; Ajeesh MO

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