Low temperature magnetic properties of Gd doped CaMnO3

Abstract

The Gadolinium (Gd) doped CaMnO 3 or Ca 0.7 Gd 0.3 MnO 3 (CGMO), structural and magnetic behavior were investigated through the X-ray diffraction and DC magnetization measurements. The high quality CGMO polycrystalline were prepared through the multiple heat treatment of solid-state reaction method. The X-ray diffraction measurement confirms the formation of single-phase with orthorhombic structure and Pnma space group. Scanning electron microscopy study reveals the surface morphology and average grain size about 2 μm. Rietveld refinement techniques were used to obtain the room temperature (RT) atomic parameters. The obtained atomic parameters of CGMO are a = 5.3465(4) Å, b = 7.5001 (5) Å and c = 5.3184 (4) Å are well matching with CaMnO 3 . Temperature-dependent (4–300 K) magnetic susceptibility (M)T measurements were carried out on CGMO at 500 Oe. Low-temperature magnetic susceptibility (ZFC and FC curves) confirms the magnetic transition i.e, paramagnetic to antiferromagnetic phase (T N ) at 67 K, and surprisingly below 10 K magnetic moments are increasing, it may be due to the formation of weak ferromagnetic ordering. Curie Weiss fitting was carried out on low-temperature inverse susceptibility of field cooled curve which shows hump around 67 K and below 10 K. From the Curie-Weiss fitting paramagnetic curie constant θp ∼ -72 K extracted, which is a clear indication of the formation of antiferromagnetic ordering and below 10 K weak ferromagnetic interaction.