arXiv:1410.2460 · Journal of Statistical Mechanics Theory and Experiment

Magnetocaloric effect in the spin-1/2 chain with competing interactions

Thiago Silva Tavares, G A P Ribeiro

Published Nov 18, 2014• 9 citations

Abstract

We study the magnetocaloric effect for the integrable antiferromagnetic Heisenberg spin chain with competing interactions. We computed the Grüneisen parameter, which is closely related to the magnetocaloric effect, for the quantum spin chain in the thermodynamic limit. This is obtained by means of the solution of a set of non-linear integral equations, which describes the thermodynamics of the model. We also provide results for the entropy S and the isentropes in the ( H , T ) plane.

DOI: 10.1088/1742-5468/2014/11/p11026

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arXiv:1410.2460 · Journal of Statistical Mechanics Theory and Experiment

Magnetocaloric effect in the spin-1/2 chain with competing interactions

Thiago Silva Tavares, G A P Ribeiro

Published Nov 18, 2014• 9 citations

arXiv HTML PDF

Abstract

DOI: 10.1088/1742-5468/2014/11/p11026

Related papers

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Physical Review BDec 8, 200810 citations

We calculate the entropy and cooling rate of the antiferromagnetic spin-

\frac{1}{2}

XXZ

chain under an adiabatic demagnetization process using the quantum transfer-matrix technique and nonlinear integral equations. The limiting case of the Ising chain (corresponding to infinitely large anisotropy) is presented for comparison. Our exact results for the Heisenberg chain are used as a cross-check for the numerical exact diagonalization as well as quantum Monte Carlo simulations and allow us to benchmark the numerical methods. Close to field-induced quantum phase transitions we observe a large magnetocaloric effect. Furthermore, we verify universal low-temperature power laws in the cooling rate and entropy, in particular, linear scaling of entropy with temperature

T

in the gapless Luttinger-liquid state and scaling as

\sqrt{T}

at field-induced transitions to gapped phases.

Motivated by the recently developed [T. Plackowski et al., Rev. Sci. Instrum. 73, 2755 (2002)] technique for measuring isothermal magnetocaloric coefficient

({M}_{T})

, we revisit the thermodynamic properties of coupled spin chains in a field. The coupled Ising antiferromagnetic chains in two and three dimensions, quantum

XY

chain in a transverse field, and Heisenberg chain are considered. For the Ising model the shift of the critical temperature under magnetic field and dependence of

{M}_{T}

on interchain coupling are found. The field dependence of

{M}_{T}

for several models is presented. It is demonstrated that in the disordered phase in the presence of antiferromagnetic fluctuations,

{M}_{T}

changes sign at some value of the magnetic field. Generally,

{M}_{T}

is negative if magnetic field competes with a short-range order, and consequently it can be an indicator of the change in the short-range correlation.