We study dipolarly coupled three-dimensional spin systems in both the microcanonical and the canonical ensembles by introducing appropriate numerical methods to determine the microcanonical temperature and by realizing a canonical model of heat bath. In the microcanonical ensemble, we show the existence of a branch of stable antiferromagnetic states in the low-energy region. Other metastable ferromagnetic states exist in this region: by externally perturbing them, an effective negative specific heat is obtained. In the canonical ensemble, for low temperatures, the same metastable states are unstable and reach a new branch of more robust metastable states which is distinct from the stable one. Our statistical physics approach allows us to put some order in the complex structure of stable and metastable states of dipolar systems.

Effective negative specific heat by destabilization of metastable states in dipolar systems / Loladze, V.; Dauxois, T.; Khomeriki, R.; Ruffo, S.. - In: PHYSICAL REVIEW. E. - ISSN 2470-0045. - 101:3(2020), p. 030102. [10.1103/PhysRevE.101.030102]

Effective negative specific heat by destabilization of metastable states in dipolar systems

Ruffo S.
2020

Abstract

We study dipolarly coupled three-dimensional spin systems in both the microcanonical and the canonical ensembles by introducing appropriate numerical methods to determine the microcanonical temperature and by realizing a canonical model of heat bath. In the microcanonical ensemble, we show the existence of a branch of stable antiferromagnetic states in the low-energy region. Other metastable ferromagnetic states exist in this region: by externally perturbing them, an effective negative specific heat is obtained. In the canonical ensemble, for low temperatures, the same metastable states are unstable and reach a new branch of more robust metastable states which is distinct from the stable one. Our statistical physics approach allows us to put some order in the complex structure of stable and metastable states of dipolar systems.
101
3
030102
030102
https://journals.aps.org/pre/abstract/10.1103/PhysRevE.101.030102
Loladze, V.; Dauxois, T.; Khomeriki, R.; Ruffo, S.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11767/116489
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