Quantum spin-liquid in Ba₃CuSb₂O₉ epitaxial thin films

Abstract

Hexagonal perovskite materials are emerging quantum spin liquid systems providing a fertile ground to realize novel quantum phenomena. The epitaxially grown thin films of such materials offer a compelling approach to utilize exotic quantum phases for device applications with better control over the structure. We fabricate the intriguing quantum spin liquid triple perovskite Ba3CuSb2O9 epitaxially onto a MgO (100) substrate by pulsed laser deposition technique as well as in bulk form for comparison. The presence of only (00l) parallel planes of Ba3CuSb2O9 in X-ray diffraction validates the epitaxial growth of the thin film. Temperature-dependent magnetization of thin film reveals no magnetic ordering down to 2 K, with a large antiferromagnetic Curie-Weiss temperature (θCW ≈ − 11.68 K). This indicates strong magnetic frustration and quantum spin liquid behaviour, similar to bulk Ba3CuSb2O9. The presence of magnetic correlations at low temperature (in the quantum spin liquid state) is further confirmed by analysing the low temperature magnetic isotherms. These experimental findings underscore the potential of this quantum material for its use in quantum technologies.