Efeito magnetocalórico na rede kagomé antiferromagnética com campos desordenados

Abstract

We explore the magnetocaloric effect (MCE) in a geometrically frustrated system under the influence of disordered magnetic fields. We consider Ising spins on the antiferromagnetic kagomé lattice in the presence of local random fields (RFs) following a bimodal probability distribution. The magnetic and thermodynamic responses of this model are investigated using cluster mean-field theory (CMF). The obtained results show that RFs deeply affect the system’s behavior, reducing the critical temperature Tc and creating new magnetization plateaus. A promising magnetocaloric potential is observed at intermediate temperatures in the critical regime, 0.8 ≤ T/J ≤ 1.1 (particularly in the paramagnetic phase) and moderate external field intensities, 2 ≤ h/J ≤ 4, supported by the large isothermal entropy change associated with the high degeneracy of the kagome lattice ground state. The findings present in this dissertation support that dilution, which can introduce the physics of random fields, can increase the temperature range associated with enhanced MCE in frustrated magnets.