Magnetocaloric effect in an Ising–Heisenberg diamond chain with direct monomer spin couplings

Abstract

We study the magnetocaloric effect (MCE) in a spin’ distorted Ising–Heisenberg diamond chain with direct monomer spin couplings. The ground state, isoentropy curves, and adiabatic cooling rate are examined within an exact analytical approach based on the transfer‐matrix technique. We find that the enhancing MCE in the vicinity of the critical field is very sensitive to the nature of field‐induced phase transitions. When the ground‐state phase transitions result from breaking up quantum entanglement states of Heisenberg spins, close to these critical fields, the signal associated with the cooling rate is very small and strongly suppressed by thermal fluctuations. By contrast, the one near the saturation field corresponding to the destruction of antiferromagnetic Ising spin order is considerably large and presents a complex temperature dependence. Interestingly, it can even be enhanced by temperature; this property reflects the intrinsic properties of the antiferromagnetic Ising spin chain and favors the use of frustrated antiferromagnets as promising working substances in low‐temperature magnetic refrigeration.