Magnetic phase diagram, critical behavior, and two-dimensional to three-dimensional crossover in the triangular lattice antiferromagnet $\mathrm{Rb}\mathrm{Fe}{(\mathrm{Mo}{\mathrm{O}}_{4})}_{2}$

Magnetic phase diagram, critical behavior, and two-dimensional to three-dimensional crossover in the triangular lattice antiferromagnet $Rb Fe {(Mo O_{4})}_{2}$

L. E. Svistov, A. I. Smirnov, L. A. Prozorova, O. A. Petrenko, A. Micheler, N. Büttgen, A. Ya. Shapiro, and L. N. Demianets

Phys. Rev. B 74, 024412 – Published 17 July 2006

Abstract

We have studied the magnetic and thermodynamic properties as well as the NMR spectra of the quasi-two-dimensional (quasi-2D) Heisenberg antiferromagnet $Rb Fe {(Mo O_{4})}_{2}$ . The observed temperature dependence of the order parameter, the critical indices, and the overall magnetic $H − T$ phase diagram are all in a good agreement with the theoretical predictions for a 2D $X Y$ model. The temperature dependence of the specific heat at low temperature demonstrates a crossover from a $T^{2}$ law characteristic of a two-dimensional antiferromagnet to a three-dimensional $T^{3}$ law.