Crystal Growth and Anisotropic Magnetic Properties of RAg$_2$Ge$_2$ (R = Pr, Nd and Sm) Single Crystals

TL;DR

This study successfully grew single crystals of RAg$_2$Ge$_2$ (R = Pr, Nd, Sm), revealing their anisotropic magnetic properties and antiferromagnetic ordering temperatures, with detailed insights into their magnetic anisotropy and metamagnetic transitions.

Contribution

First detailed report on single crystal growth and anisotropic magnetic properties of RAg$_2$Ge$_2$ compounds with ThCr$_2$Si$_2$ structure.

Findings

PrAg$_2$Ge$_2$ orders antiferromagnetically at 12 K.

NdAg$_2$Ge$_2$ orders antiferromagnetically at 2 K.

SmAg$_2$Ge$_2$ orders antiferromagnetically at 9.2 K.

Abstract

We report the single crystal growth and anisotropic magnetic properties of the tetragonal RAg$_2$Ge$_2$ (R = Pr, Nd and Sm) compounds which crystallize in the ThCr$_2$Si$_2$ type crystal structure with the space group \textit{I4/mmm}. The single crystals of RAg$_2$Ge$_2$ (R = Pr, Nd and Sm) were grown by self-flux method using Ag:Ge binary alloy as flux. From the magnetic studies on single crystalline samples we have found that PrAg$_2$Ge$_2$ and NdAg$_2$Ge$_2$ order antiferromagnetically at 12 K and 2 K respectively, thus corroborating the earlier polycrystalline results. SmAg$_2$Ge$_2$ also orders antiferromagnetically at 9.2 K. The magnetic susceptibility and magnetization show a large anisotropy and the easy axis of magnetization for PrAg$_2$Ge$_2$ and NdAg$_2$Ge$_2$ is along the [100] direction where as it changes to [001] direction for SmAg$_2$Ge$_2$. Two metamagnetic transitions were observed in NdAg$_2$Ge$_2$ at $H_{\rm m1}$ = 1.25 T and $H_{\rm m2}$ =3.56 T for the field parallel to [100] direction where as the magnetization along [001] direction was linear indicating the hard axis of magnetization.