Quantum correlations and quantum phase transitions in mixed spin-(1/2,1) Heisenberg chain with single-ion anisotropy

We study the quantum phase transitions occurring in the ferrimagnetic mixed spin-(1/2, , 1) chain with single-ion anisotropy under the influence of an external magnetic field. Using quantum information theory concepts, we unravel these transitions without prior knowledge of system symmetries or order parameters. It is observed that a more comprehensive understanding of quantum phase transitions can be obtained using a deep analysis of multipartite negativity. The entanglement characteristics of the mixed system are explored by employing numerical diagonalization through the Lanczos algorithm. Fidelity susceptibility reveals quantum phase transitions, notably at the degeneracy lifting point where magnetic effects cancel. A low-temperature phase diagram emerges, delineating four distinct phases: quantum spin-liquid, Lieb-Mattis ferrimagnetic, Luttinger spin-liquid, and fully polarized. We observe a direct second-order transition from Lieb-Mattis ferrimagnetic to a fully polarized phase under specific conditions. Results are extrapolated to the thermodynamic limit, providing insights into macroscopic behavior.