Breakdown of thermalization in spin chains with single-ion anisotropy

The principles of ergodicity and thermalization constitute the foundation of statistical mechanics, positing that a many-body system progressively loses its local information as it evolves. Nevertheless, these principles can be disrupted when thermalization dynamics lead to the conservation of local...

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Bibliographic Details
Published in:Scientific reports 2024-10, Vol.14 (1), p.25315-13, Article 25315
Main Authors: Sousa, M. G., Costa, R. F. P., Neto, G. D. de Moraes, Vernek, E.
Format: Article
Language:English
Subjects:
639/766
639/766/119/2795
639/766/483/640
Anisotropy
Humanities and Social Sciences
Information systems
Localization
Magnetic fields
multidisciplinary
Science
Science (multidisciplinary)
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Summary:The principles of ergodicity and thermalization constitute the foundation of statistical mechanics, positing that a many-body system progressively loses its local information as it evolves. Nevertheless, these principles can be disrupted when thermalization dynamics lead to the conservation of local information, as observed in the phenomenon known as many-body localization. Quantum spin chains provide a fundamental platform for exploring the dynamics of closed interacting quantum many-body systems. This study explores the dynamics of a spin chain with S ≥ 1 / 2 within the  incorporating a non-uniform magnetic field and single-ion anisotropy. Through the use of exact numerical diagonalization, we unveil that a nearly constant-gradient magnetic field suppresses thermalization, a phenomenon termed Stark many-body localization (SMBL), previously observed in S = 1 / 2 chains. Furthermore, our findings reveal that the sole presence of single-ion anisotropy is sufficient to prevent thermalization in the system. Interestingly, when the magnitudes of the magnetic field and anisotropy are comparable, they compete, favoring delocalization. Despite the potential hindrance of SMBL by single-ion anisotropy in this scenario, it introduces an alternative mechanism for localization. Our interpretation, considering local energetic constraints and resonances between degenerate eigenstates, not only provides insights into SMBL but also opens avenues for future experimental investigations into the enriched phenomenology of disordered free localized S ≥ 1 / 2 systems.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-024-74966-5