Effect of Ge substitution for Si on the anomalous magnetocaloric and magnetoresistance properties of GdMn2Si2 compounds

TL;DR

This study investigates how substituting Ge for Si in GdMn2Si2 compounds affects their magnetic, magnetocaloric, and magnetoresistance properties, revealing significant changes in magnetic order and large magnetoresistance linked to canted magnetic structures.

Contribution

It provides new insights into the impact of Ge substitution on magnetic phase transitions, magnetocaloric effects, and magnetoresistance in GdMn2Si2 compounds, highlighting the role of canted magnetic structures.

Findings

Magnetic transition changes from second to first order with Ge substitution.

Maximum magnetocaloric effect of 5.9 J/kgK and 1.2 K temperature change in GdMn2Ge2.

Large positive magnetoresistance up to 22% in GdMn2Ge2.

Abstract

The effect of Ge substitution on the magnetization, heat capacity, magnetocaloric effect and magnetoresistance of GdMn2Si2-xGex (x=0, 1, and 2) compounds has been studied. The magnetic transition associated with the Gd ordering is found to change from second order to first order on Ge substitution. Magnetic contributions to the total heat capacity and the entropy have been estimated. Magnetocaloric effect has been calculated in terms of adiabatic temperature change (deltaTad) as well as isothermal magnetic entropy change (deltaSM) using the heat capacity data. The temperature dependence of the magnetocaloric effect in all the three compounds have shown broad peaks. The maximum values of deltaSM and deltaTad for GdMn2Ge2 are found to be 5.9 J/kgK and 1.2 K, respectively. The magnetoresistance is found to be very large and positive with a maximum value of about 22% in the case of GdMn2Ge2. In the other two compounds also, the magnetoresistance is predominantly positive, except in the vicinity of the Gd ordering temperature. The anomalous nature of the magnetocaloric effect and the magnetoresistance has been attributed to the canted magnetic structure of these compounds.