Cluster mean field study of the Heisenberg model for CuInVO₅

The understanding of interacting quantum spin systems requires exact solutions for the relevant Hamiltonian. Brute-force exact diagonalization (ED) is computationally limited to small lattice sizes whereas in the limit of single-site MFT effects arising from lattice geometry and competing interactions are missed. Cluster MFT (CMFT) stands in middle of both the limits, treating intracluster interactions exactly while keeping intercluster couplings at the level of mean fields. Spatial correlations that are completely neglected in MFT can be partly recovered in the CMFT framework. Presented are results of a cluster mean-field study on a quasi one-dimensional magnet CuInVO₅, which is a chain of alternating ferromagnetic-antiferromagnetic coupled spin-1/2 Cu atoms