Realization of the anisotropic XY model in a Tb(III)-W(V) chain compound

TL;DR

This study demonstrates the realization of a 1D anisotropic XY ferromagnet in a Tb(III)-W(V) chain compound, showing experimental evidence of ferromagnetic transition and matching theoretical models through simulations.

Contribution

First experimental realization and detailed characterization of a 1D anisotropic XY model in a cyanido-bridged chain compound, combining measurements with quantum Monte Carlo simulations.

Findings

Observation of ferromagnetic transition at 1.15 K.

Specific heat matches the 1D S=1/2 XY model with anisotropy.

Excellent agreement between experimental data and simulations.

Abstract

We present evidence of 1D S=1/2 anisotropic XY ferromagnetism in the paramagnetic phase of the cyanido-bridged chain complex [Tb(pzam)3(H2O)M(CN)8]H2O, with M=W(V), based upon the measurement of the specific heat, the uniform susceptibility and the magnetization curve on a powder sample. Both the specific heat and the susceptibility exhibit a transition peak to long-range ferromagnetism, mediated by the residual interchain couplings, at a critical temperature Tc=1.15 K. Yet in the temperature range T > Tc the specific heat exhibits a broad Schottky anomaly which can be very well fitted by the exact result for the 1D S=1/2 XY model with strong anisotropy in the XY plane (Jx = 1.89 K, Jy=2Jx). For the analysis of the susceptibility and magnetization, not directly accessible theoretically via the exact solution of the XY model, we resort to numerically exact quantum Monte Carlo simulations. Very good agreement is found between the powder-sample data and the Monte Carlo data using an effective average g-factor.