Synthesis and Anisotropic Magnetism in Quantum Spin Liquid Candidates $A$YbSe$_2$ ($A$ = K and Rb)

Abstract

Quantum spin liquid (QSL) state in rare-earth triangular lattice has attracted much attention recently due to its potential application in quantum computing and communication. Here we report the single-crystal growth synthesis, crystal structure characterizations and magnetic properties of AYbSe 2 (A= K, Rb) compounds. The X-ray diffraction analysis shows that AYbSe 2 (A = K and Rb) crystallizes in a trigonal space group, R-3m (No. 166) with Z = 3. AYbSe 2 possesses a two-dimensional (2D) Yb-Se-Yb layered structure formed by edged-shared YbSe 6 octahedra. The magnetic properties are highly anisotropic for both title compounds and no long-range order is found down to 0.4 K, revealing the possible QSL ground state in these compounds. The isothermal magnetization exhibits one-third magnetization plateau when the magnetic fields are applied in ab-plane. Heat capacity is performed along both ab-plane and c-axis, and features the characteristic dome for triangular magnetic lattice compounds as a function of magnetic fields. Due to the change of the interlayer and intralayer distance of Yb 3+ , the dome shifts to low fields from KYbSe 2 to RbYbSe 2 . All these results indicate the AYbSe 2 family presents unique frustrated magnetism close to the possible QSL and noncolinear spin states.

Nearly-Resonant Crystalline-Phononic Coupling in Quantum Spin Liquid Candidate CsYbSe$_2$

“…Yb delafossites 15 like NaYbS 2 16,17 , NaYbSe 2 18-20 , NaYbO 2 [21][22][23] , CsYbSe 2 [24][25][26][27] , and KYbSe 2 28,29 -with effective spin S eff = 1/2 from Yb 3+ ions and antiferromagnetic coupling decorating 2D triangular latticesare popular candidates for the realization of quantum spin liquids. Easy-plane magnetic anisotropy results in a plateau at one-third of the saturation magnetization due to strong spin fluctuations 19,21,23,24 .…”