Thermodynamics of the exactly solvable spin-electron tetrahedral chain

TL;DR

This paper investigates the thermodynamic properties and magnetocaloric effects of an exactly solvable spin-electron tetrahedral chain with alternating Ising spins and mobile electrons, revealing enhanced MCE under specific magnetic field conditions.

Contribution

It introduces an exactly solvable model of a spin-electron tetrahedral chain and analyzes its thermodynamics and magnetocaloric effects under different magnetic interactions.

Findings

Enhanced MCE in ferromagnetic interaction at low fields

Enhanced MCE in antiferromagnetic interaction near specific field

Exact thermodynamic solutions for the model

Abstract

An exactly solvable spin-electron tetrahedral chain, where the Ising spins localized at nodal lattice sites regularly alternate with three equivalent lattice sites available for one mobile electron is considered. The system with ferromagnetic interaction between the Ising spins and electrons exhibits an enhanced magnetocaloric effect (MCE) in the limit $H/|J|\to 0$ when the entropy is very small, whereas the system with antiferromagnetic interaction between the Ising spins and electrons exhibits an enhanced MCE around the field $H/J=1$ when the entropy is sufficiently close to the value $S/2N = \ln[(1+\sqrt{5})/2]$. We study the thermodynamics of the system in these field regions.