Magnetic phase diagram of EuPdSn_2

TL;DR

This paper constructs a detailed magnetic phase diagram of EuPdSn_2 using magnetization, susceptibility, heat capacity, and neutron diffraction, revealing complex magnetic behavior and deviations from mean-field predictions.

Contribution

It introduces a method to separate ferromagnetic and antiferromagnetic contributions in EuPdSn_2 and discusses the non-mean-field behavior of specific heat and entropy.

Findings

Separation of FM and AFM contributions to susceptibility.

Deviation of specific heat from mean-field prediction.

Observation of thermodynamic relationship dM/dT=dS/dB=0.

Abstract

A magnetic phase diagram for EuPdSn_2 is constructed based on magnetization, DC-susceptibility and specific heat as a function of applied field, and neutron diffraction results at zero field. The contribution of the ferromagnetic FM and antiferromagnetic AFM components to the measured magnetic susceptibility can be separated and weighted as a function of the applied field B by taking the temperature dependence of the neutron counts from the FM phase at B=0 as a reference. In the magnetically ordered phase, the temperature dependence of the specific heat does not follow the mean-field prediction for the Eu^{2+} J=7/2 quantum number rather that for J=5/2. This deviation and the consequent discrepancy for the entropy is discussed in the context of a non-Zeeman distribution of the eight fold ground state. Comparing the respective variations of magnetization M(T,B) and entropy S(T,B), the thermodynamic relationship dM/dT=dS/dB=0 is observed for the ranges: 0<T<10K and 0<B<0.4T.