Exchange Anisotropy in Metallic Glasses

Abstract

Magnetic properties of centrifugal spin quenched ribbons of metallic glasses in the system Fe‐Mn‐P‐B‐Al were studied from room temperature to 1.5°K, with applied fields up to 15.3 kOe. The magnetization vs. temperature curve for $({\mathrm{Fe}}_{\text{.5}}{\mathrm{Mn}}_{\text{.5}}{\mathrm{)\hspace{0.17em}}}_{\text{.75}}{\mathrm{P}}_{\text{.16}}{\mathrm{B}}_{\text{.06}}{\mathrm{Al}}_{\text{.03}}$ has a broad maximum near 20°K, observed after cooling in zero applied field. Cooling from higher temperatures in the presence of 15.3 kOe applied field, essentially eliminated the broad maximum and established an asymmetrical displaced hysteresis loop at 1.5°K. The intrinsic coercive force was nearly zero on one side, and 7200 oersteds on the other, while the remanence was zero on one side and 3.5 e.m.u./g on the other. Magnetically cycling the field cooled sample several times with ±15.3 kOe at 1.5°K changed the magnetic state of the specimen, resulting in a nearly symmetrical hysteresis loop, with lower coercivity and remanence. Cooling in zero field established a symmetrical hysteresis loop with lower coercivity of ±1600 Oe. Magnetic saturation was not achieved by any treatment, and the maximum value of magnetization obtained for the field cooled sample was only 7.5 e.m.u./g. These magnetic properties are interpreted as evidence for ferromagnetic‐antiferromagnetic “exchange anisotropy” in this alloy.¹