Magnetocrystalline anisotropy in the Kondo lattice compound CeAgAs$_2$

TL;DR

This study investigates the anisotropic magnetic and electronic properties of CeAgAs$_2$, revealing antiferromagnetic order, strong magnetocrystalline anisotropy, and Kondo lattice behavior in a newly characterized orthorhombic crystal structure.

Contribution

First detailed report on the single crystal growth and anisotropic properties of CeAgAs$_2$, highlighting its magnetic ordering, anisotropy, and Kondo lattice characteristics.

Findings

CeAgAs$_2$ orders antiferromagnetically at 6 K and 4.9 K.

The compound exhibits strong magnetocrystalline anisotropy with an easy axis along [010].

CeAgAs$_2$ shows Kondo lattice behavior with characteristic electronic properties.

Abstract

We report on the single crystal growth and anisotropic physical properties of CeAgAs$_2$. The compound crystallizes as on ordered variant of the HfCuSi$_2$-type crystal structure and adopts the orthorhombic space group $Pmca$~(\#57) with two symmetry inequivalent cerium atomic positions in the unit cell. The orthorhombic crystal structure of our single crystal was confirmed from the powder x-ray diffraction and from electron diffraction patterns obtained from the transmission electron microscope. The anisotropic physical properties have been investigated on a good quality single crystal by measuring the magnetic susceptibility, isothermal magnetization, electrical transport and heat capacity. The magnetic susceptibility and magnetization measurements revealed that this compound orders antiferromagnetically with two closely spaced magnetic transitions at $T_{\rm N1} = 6$~K and $T_{\rm N2} = 4.9$~K. Magnetization studies have revealed a large magnetocrystalline anisotropy due to the crystalline electric field (CEF) with an easy axis of magnetization along the [010] direction. The magnetic susceptibility measured along the [001] direction exhibited a broad hump in the temperature range 50 to 250~K, while typical Curie-Weiss behaviour was observed along the other two orthogonal directions. The electrical resistivity and the heat capacity measurements revealed that CeAgAs$_2$ is a Kondo lattice system with a magnetic ground state.