Decoupling the structural and magnetic phase transformations in magneto-optic MnBi thin films by the partial substitution of Cr for Mn

The first-order nature of the magnetic phase transformation at 360 degrees C and the presence of a-Bi;rich eutectic at 265 degrees C have inhibited the application of MnBi thin films for high density magneto-optical data storage. It is suggested that partial substitution of Cr for Mn should both lower;the Curie temperature, T-c, and decouple the lattice and magnetic transitions so as to allow reversible Curie point writing. It is found experimentally that 10% substitution of Cr for Mn reduces the apparent T-c to similar to 250 degrees C while retaining a Kerr rotation angle greater than 1 degrees at 633 nm, as measured through the silica glass substrate. Observations of increasing H-c with temperature in both MnBi and (Mn,Cr)Bi thin films suggest that the low-temperature phase is ferrimagnetic. (C) 1998 American Institute of Physics.