Crystal growth and recovery of ferromagnetism during thermal cycle in MnBi films

摘要

this paper reports details of the magnetic domain configuration during crystal growth and the exciting phenomena during the thermal cycle around the Curie temperature. The experiments suggest the conditions for producing large hexagonal single‐crystal MnBi platelets: (i) Substrates must be clean; (ii) Bi and Mn should be evaporated in this sequence with the atomic ratio of Mn to Bi between 0.5 and 0.7; and (iii) annealing should be done with the thermal cycle through the critical temperatures Tc1 (about 360 °C) and Tc2 (about 350 °C), under high vacuum. On the other hand, the most useful films for Curie‐point writing with high bit density are produced by annealing the double‐layer film, with the ratio of Mn to Bi between 1.5 and 2.0, at a low temperature of 200–300 °C.