# Ising-type Magnetic Anisotropy in CePd$_2$As$_2$

## TL;DR

This study reveals strong Ising-type magnetic anisotropy in CePd$_2$As$_2$, driven by crystal electric field effects, with a low-temperature antiferromagnetic transition and field-induced spin-flip transition along the c-axis.

## Contribution

The paper provides a detailed CEF analysis and experimental evidence of Ising-type anisotropy and magnetic transitions in CePd$_2$As$_2$, highlighting its unique magnetic properties.

## Key findings

- Large c-axis magnetic moment due to CEF effects
- Uniaxial antiferromagnetic transition at 14.7 K
- Field-induced spin-flip transition at 0.95 T

## Abstract

We investigated the anisotropic magnetic properties of CePd$_2$As$_2$ by magnetic, thermal and electrical transport studies. X-ray diffraction confirmed the tetragonal ThCr$_2$Si$_2$-type structure and the high-quality of the single crystals. Magnetisation and magnetic susceptibility data taken along the different crystallographic directions evidence a huge crystalline electric field (CEF) induced Ising-type magneto-crystalline anisotropy with a large $c$-axis moment and a small in-plane moment at low temperature. A detailed CEF analysis based on the magnetic susceptibility data indicates an almost pure $\langle\pm5/2 \rvert$ CEF ground-state doublet with the dominantly $\langle\pm3/2 \rvert$ and the $\langle\pm1/2 \rvert$ doublets at 290 K and 330 K, respectively. At low temperature, we observe a uniaxial antiferromagnetic (AFM) transition at $T_N=14.7$ K with the crystallographic $c$-direction being the magnetic easy-axis. The magnetic entropy gain up to $T_N$ reaches almost $R\ln2$ indicating localised $4f$-electron magnetism without significant Kondo-type interactions. Below $T_N$, the application of a magnetic field along the $c$-axis induces a metamagnetic transition from the AFM to a field-polarised phase at $\mu_0H_{c0}=0.95$ T, exhibiting a text-book example of a spin-flip transition as anticipated for an Ising-type AFM.