Spin resonances in amorphous alloy films

Spin resonance studies have been done on a series of amorphous thin films of Y-Co, Zr-Co, La-Fe, Zr-Fe and Lu-Fe alloys prepared by co-evaporation onto room temperature substrates. Y-Co alloys behave in accord with static magnetic measurements. In Y29Co71 and Y20Co80 the exchange stiffness has been determined to be 0.6×10-6 and 0.4×10-6 erg/cm, respectively. Zr-Co alloys, especially with high Co concentration show highly unexpected behavior by exhibiting several rather narrow resonances. The RE-Fe alloys are also anomalous in that they give ferromagnetic resonances at 300 K while static measurements fail to show any evidence for long range order.