Magnetic properties of ion-beam sputtered Cr₃Fe-alloy films

Abstract

Results of detailed magnetization study on ion-beam sputtered films of disordered Cr₇₀Fe₃₀ and Cr₇₅Fe₂₅ alloys of varying thickness reveal strong departure from the bulk behaviour even for a film as thick as d=470 nm; at this thickness, the Curie temperature T_C has dropped by roughly a factor of 2. In the range 9.4 nm≤d470 ≤nm, T_C α d^-1. This is contrary to Fe or Cr thin films where intrinsic magnetic properties vary with d only for ultra-low thicknesses. Film stress in combination with a high degree of inherent chemical disorder, long-range ferromagnetic and antiferromagetic exchange interactions are thought to dominate variations of magnetic properties in the intermediate film thickness range. Hysteresis effects alone cannot account for the re-entrant spin glass-like behaviour observed at temperatures T«T_C.