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arXiv · 2309.14076

Spectral Crossovers and Universality in Quantum Spin-chains Coupled to Random Fields

Debojyoti Kundu·Santosh Kumar·Subhra Sen Gupta
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Abstract

We study the spectral properties of and spectral-crossovers between different random matrix ensembles (Poissonian, GOE, GUE) in correlated spin-chain systems, in the presence of random magnetic fields, and the scalar spin-chirality term, competing with the usual isotropic and time-reversal invariant Heisenberg term. We have investigated these crossovers in the context of the level-spacing distribution and the level-spacing ratio distribution. We use random matrix theory (RMT) analytical results to fit the observed Poissonian-to-GOE and GOE-to-GUE crossovers, and examine the relationship between the RMT crossover parameter {\lambda} and scaled physical parameters of the spin-chain systems in terms of a scaling exponent. We find that the crossover behavior exhibits universality, in the sense that it becomes independent of lattice size in the large Hamiltonian matrix dimension limit.

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Debojyoti Kundu, Santosh Kumar, Subhra Sen Gupta. 2023-09-25. Spectral Crossovers and Universality in Quantum Spin-chains Coupled to Random Fields. https://doi.org/10.1103/physrevb.105.014205

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