Néel-type antiferromagnetic order and magnetic field–temperature phase diagram in the spin-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mfrac><mml:mn>1</mml:mn><mml:mn>2</mml:mn></mml:mfrac></mml:math> rare-earth honeycomb compound <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>YbCl</mml:mi><mml:msub><mml:mrow/><mml:mn>3</mml:mn></mml:msub></mml:math>
Jie Xing, Erxi Feng, Yaohua Liu, Eve Emmanouilidou, Chaowei Hu, Jinyu Liu, David Graf, A. P. Ramirez, Gang Chen, Huibo Cao, Ni Ni
Abstract
Most of the searches for Kitaev materials deal with $4d/5d$ magnets with spin-orbit-coupled $J=1/2$ local moments such as iridates and $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$. Here we propose the monoclinic ${\mathrm{YbCl}}_{3}$ with a ${\mathrm{Yb}}^{3+}$ honeycomb lattice for the exploration of Kitaev physics. We perform thermodynamic, $ac$ susceptibility, angle-dependent magnetic torque, and neutron diffraction measurements on ${\mathrm{YbCl}}_{3}$ single crystal. We find that the ${\mathrm{Yb}}^{3+}$ ion exhibits a Kramers doublet ground state that gives rise to an effective spin ${J}_{\text{eff}}=1/2$ local moment. The compound exhibits short-range magnetic order below 1.20 K, followed by a long-range N\'eel-type antiferromagnetic order at 0.60 K, below which the ordered ${\mathrm{Yb}}^{3+}$ spins lie in the $ac$ plane with an angle of 16(11)${}^{\ensuremath{\circ}}$ away from the $a$ axis. These orders can be suppressed by in-plane and out-of-plane magnetic fields at around 6 and 10 T, respectively. Moreover, the N\'eel temperature varies nonmonotonically under the out-of-plane magnetic fields, suggesting a reduced spin dimensionality. Together with the strong in-plane magnetic anisotropy and the reduced order moment 0.8(1) ${\ensuremath{\mu}}_{B}$ at 0.25 K, all indicate that ${\mathrm{YbCl}}_{3}$ could be a two-dimensional spin system to proximate the Kitaev physics.