Ising-type Magnetic Anisotropy in CePd${}_2$As${}_2$

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 $⟨\pm 5/2|$ CEF ground-state doublet with the dominantly $⟨\pm 3/2|$ and the $⟨\pm 1/2|$ 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 $R\ln 2$ 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 $\hat{I}{¼}_0{H}_{c0}=0.95$ T, exhibiting a text-book example of a spin-flip transition as anticipated for an Ising-type AFM.

9 Pages, 8 figures