Huge negative magnetic hyperfine fields for 111Cd probe nuclei in the Fe3X (X=C, Ge, and Ga) compounds with specific properties

Abstract

In recent years, Fe3X (X = C, Ga, and Ge) alloys are actively investigated experimental and theoretical methods due to their potential practical use as invar, magnetostrictive materials, and multi-layered ferromagnetic film [1-3]. The Fe3C alloy was studied by nuclear resonant scattering on 57Fe and by x-ray emission spectroscopy at high pressure up to 50 GPa because this substance could be the major Earth’s inner core component [4, 5]. In this work we found huge negative HFs reaching a magnitude of Bhf = -46T on 111Cd probe nuclei in ferromagnetic Fe3X (X = C, Ga, and Ge) alloys by perturbed γ-γ angular correlation (PAC) spectroscopy. These values are the highest known HFs on 111Cd nuclei in metallic magnets. It was established that in Fe3C crystallizing in the orthorhombic DO11 structure (Pnma space group) 111Cd probes are placed in Feg sites with 11Fe atoms as nearest neighbours (n.n.). For Feg positions, the n.n. arrangement is similar to normal hexagonal close packing. The HF value for 111Cd atoms in Fe3C is equal to Bhf = -38.0(1) T at 77K. In tetragonal DO3 crystal structure of Fe3Ga 111Cd probes are placed in both Ga sites (12 n.n. Fe) and in FeII (8n.n.Fe). The HFs for 111Cd atoms in Fe3Ga are equal to Bhf = -39.8(1) T and Bhf = -24.2(3) T at 77K for Ga and FeII sites of 111Cd localization. In hexagonal DO19 crystal structure of Fe3Ge 111Cd probes are placed in Ge sites (12 n.n.). The HF value for 111Cd probes in Fe3Ge is equal to Bhf = -46.0(1) T at 40K. There are no any anomalies of the Bhf (T) on 111Cd nuclei in the spin reorientation region of Fe3Ge. The results of this work are analyzed with the previously obtained HF’s values on 111Cd nuclei in 3d metals and their alloys including Heusler alloys.