Anisotropic magnetic properties of CeAg$_2$Ge$_2$ single crystal

TL;DR

This study reports the successful growth and comprehensive analysis of anisotropic magnetic properties of CeAg$_2$Ge$_2$ single crystals, revealing antiferromagnetic behavior, magnetic anisotropy, and detailed crystal electric field level splitting.

Contribution

First successful growth of CeAg$_2$Ge$_2$ single crystals using flux method and detailed characterization of their anisotropic magnetic properties.

Findings

Antiferromagnetic transition at 4.6 K

Magnetic entropy reaches R ln 4 at 20 K

Easy axis of magnetization along the a-axis

Abstract

In order to investigate the anisotropic magnetic properties of CeAg$_2$Ge$_2$, we have successfully grown the single crystals, for the first time, by high temperature solution growth (flux) method. We have performed a detailed study of the grown single crystals by measuring their electrical resistivity, magnetic susceptibility, magnetization, specific heat and magnetoresistance. A clear anisotropy and an antiferromagnetic transition at $T_{\rm N}$ = 4.6 K have been observed in the magnetic properties. The magnetic entropy reaches $R$ ln 4 at 20 K indicating that the ground state and the first excited state are very closely spaced (a quasi-quartet state). From the specific heat measurements and crystalline electric field (CEF) analysis of the magnetic susceptibility, we have found the level splitting energies as 5 K and 130 K. The magnetization measurements reveal that the a-axis is the easy axis of magnetization and the saturation moment is $\mu_{\rm s}$ = 1.6 $\mu_{\rm B}$/Ce, corroborating the previous neutron diffraction measurements on a polycrystalline sample.