Magnetic State of Manganese in BCC FeCo and FeNi Alloys; Investigations by NMR and Magnetic Measurements

Abstract

The Mn⁵⁵ nuclear magnetic resonance (NMR) and the saturation magnetization have been measured on bcc FeCo and FeNi alloys containing small amounts of manganese at 4.2 K. Both of the observed Mn⁵⁵ resonance frequency and the deduced Mn magnetic moment show an anomalous jump at e⁄a≈8.3, where e is the number of electrons in host and a the number of host atoms. From the correspondence of the NMR and magnetic measurement results, the manganese atom is interpreted to be in a low-moment state of 0.8 μ_B for e⁄a\lesssim8.2, and in a high-moment state of 3.0 μ_B for e⁄a\gtrsim8.4. The data for e⁄a=8.3 can be explained reasonably on the assumption that about 70% of manganese is in the low-moment state and about 30% of manganese is in the high-moment state.