Improving Mean-Field Theory for Quantum Magnets

Frustrated magnets have garnered significant attention because of their potential to host exotic spin liquids, while many real material candidates exhibit magnetic orders. Due to their proximity to spin liquid phases, the semiclassical descriptions of these magnetic orders often fall short in capturing their intricate quantum behaviors. In this talk, I will introduce an improved mean-field method, named density-matrix mean-field theory (DMMFT), for these quantum magnets. Using local reduced density matrix, DMMFT can systematically incorporate the quantum fluctuations beyond conventional mean-field theories. Notably, it not only quantitatively evaluates the renormalization of order parameters induced by quantum fluctuations but also has the capability to detect the topological order of quantum phases. DMMFT offers an efficient approach to explore phases displaying unconventional quantum orders, particularly beneficial for investigating frustrated spin systems in high spatial dimensions.

Ref: https://arxiv.org/abs/2401.06236

Zoom: https://harvard.zoom.us/j/977347126

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