Magnetic Studies at the Research Institute for Iron, Steel and Other Metals

Abstract

A brief survey of several investigations is presented. (1) Spin‐flopping magnetization measurements up to 80 kOe in α Fe₂O₃ in the low‐temperature state are reported. The temperature dependence of the uniaxial anisotropy constant is obtained therefrom. Its magnitude is of the order of 10⁴ erg/cc and increases with decreasing temperature. Measurements with the field perpendicular to the trigonal axis reveal that at a temperature in the transition region (240°K), the magnetic state moves first toward the high‐temperature behavior with weak ferromagnetism, but above 60 kOe it returns to the antiferromagnetic low‐temperature state. (2) Thermomagnetic measurements on CaFeO_2.5 and CaFe₄O₇ indicate that a weak ferromagnetism appears at 400°C. From the crystal structure, a Dzyaloshinsky‐Moriya canting is suggested to account for the weak moment. (3) High‐field measurements of MnAu₂ extend to low temperatures the previous data on its transition field (screw‐type antiferromagnetism to ferromagnetism). The screw angle appears to be changing slowly even below 80°K. Longitudinal and transverse magnetostriction measurements in MnAu₂ are reported through the transition and up to 80 kOe. Relative length changes of about 10⁻⁴ are observed and significant volume contractions during the screw‐flopping and rotation stages are inferred. (4) Saturation moment and Curie point measurements of Pd‐Fe alloys (near 30 at. % Pd) are reported and compared with similar Invar‐type behavior in Ni‐Fe alloys.