MAGNETOCALORIC EFFECT IN THE ONE-DIMENSIONAL SPIN-1/2 XX MODEL WITH TWO PERIODICALLY VARYING g-FACTORS

The influence of a non-uniformity of the g-factors with period two on the magnetocaloric effect in the spin-1/2 XX chain in the transverse field has been studied. By means of the Jordan-Wigner transformation, the problem is reduced to the Hamiltonian of noninteracting spinless fermions and solved exactly. The variation of isentropes and the field dependences of the magnetic Gruneisen ratio with a change in the ratio g(2)/g(1) are analyzed. Main attention is paid to the low-temperature region. Distinctions among the magnetocaloric effect manifestations in the cases where the g-factors have different or identical signs, or if either of g-factors equals zero, are demonstrated.