Magnetic and magneto-optical properties of Tb-Fe-Co amorphous films

Abstract

Characteristics of Tb‐Fe‐Co amorphous films have been systematically investigated in order to optimize compositions suitable for magneto‐optical recording medium with high readout signal. In order to optimize alloy composition, Curie temperature T_C and compensation temperature T_comp are summarized as functions of both Tb and Co contents. Crystallization temperature T_x of Tb‐Fe‐Co amorphous films has been also measured to be about 400 °C and tends to increase with replacing Fe by either Co or Tb. To evaluate Tb‐Fe‐Co films as a magneto‐optical recording medium, carrier C and modulation noise N_mod (defined by the difference in noise before and after writing) are measured as a function of external field H_ex. It is found that written bits of large N_mod show an irregular shape, while those of small N_mod are of regular one. To reduce N_mod and obtain high readout C/N, films with lower saturation magnetization M_s (that is, low demagnetization field) at just below writing temperature are preferred.