THERMAL EXCITATIONS IN QUASI-ONE-DIMENSIONAL AMORPHOUS FERROMAGNETIC WIRE

Quasi-one-dimensional ferromagnetic amorphous wires were prepared by s wift-heavy-ion irradiation of paramagnetic YCo2 thin films. Structural and magnetic analysis revealed elongated wires with diameters in the range 1-2.5 nm depending on the incident ion energy. Strikingly differ ent behaviors for the reduced magnetization temperature dependence was observed depending on the wire diameter, whether measured by static m ethods or by ferromagnetic resonance. This is ascribed to dimensionali ty effects as previously observed in two-dimensional ultrathin films. Using spin-wave theory, the expected behavior for a one-dimensional sq uare lattice is calculated in the limit of noninteracting spin waves. Good qualitative agreement with the experimental data is obtained.