Honeycomb oxide heterostructure as a candidate host for a Kitaev quantum spin liquid
Baekjune Kang, Miju Park, Sehwan Song, Seunghyeon Noh, Daeseong Choe, Minsik Kong, Minjae Kim, Choongwon Seo, Eun Kyo Ko, Gangsan Yi, Jung‐Woo Yoo, Sungkyun Park, Jong Mok Ok, Changhee Sohn
Abstract
The Kitaev quantum spin liquidand massively quantum entangled states, are so scarce in nature that searching for new candidate systems remains a great challenge. A honeycomb heterostructure could be a promising route to realize and utilize such an exotic quantum phase by providing additional controllability of Hamiltonian and device compatibility, respectively. Here, we provide epitaxial honeycomb oxide thin film ${\mathrm{Na}}_{3}{\mathrm{Co}}_{2}{\mathrm{SbO}}_{6}$, a candidate of Kitaev quantum spin liquid proposed recently. We found a spin glass and antiferromagnetic ground states depending on Na stoichiometry, signifying not only the importance of Na vacancy control but also strong frustration in ${\mathrm{Na}}_{3}{\mathrm{Co}}_{2}{\mathrm{SbO}}_{6}$. Despite its classical ground state, the field-dependent magnetic susceptibility shows remarkable scaling collapse with a single critical exponent, which can be interpreted as evidence of quantum criticality. Its electronic ground state and derived spin Hamiltonian from optical spectroscopy are consistent with the predicted Kitaev model. Our work provides a unique route to the realization and utilization of Kitaev quantum spin liquid.