Physical properties of EuPtIn₄ intermetallic antiferromagnet

We report the physical properties of EuPtIn₄ single crystalline platelets grown by the In-flux technique. This compound crystallizes in the orthorhombic Cmcm structure with lattice parameters a=4.542(1)A., b=16.955(2)A. and c=7.389(1)A. Measurements of magnetic susceptibility, heat capacity, electrical resistivity, and electron spin resonance (ESR) reveal that EuPtIn₄ is a metallic Curie-Weiss paramagnet at high temperatures with an effective moment of ^μeff≈7.8(1)^μB due to divalent Eu ions. At low temperatures, antiferromagnetic (AFM) ordering is observed at ^TN=13.3K followed by a successive anomaly at ^T=12.6K. In addition, within the magnetic state, a spin-flop transition is observed with ^Hc~2.5T at T=1.8 K when the magnetic field is applied along the ac-plane. In the paramagnetic state, a single divalent Eu²⁺ Dysonian ESR line with a Korringa relaxation rate of b=4.1(2)Oe/K is observed. Interestingly, even at high temperatures, both ESR linewidth and electrical resistivity reveal a similar anisotropy. We discuss a possible common microscopic origin for the observed anisotropy in these physical quantities likely associated with an anisotropic magnetic interaction between Eu²⁺ 4f electrons mediated by conduction electrons.