Ferromagnetic ordering in Mn induced by thermal strain

Abstract

We report that the thermal strain due to the thermal-expansion difference between a Mn film and a semiconductor substrate is strong enough to overcome the thermal energy for a paramagnetic (PM) state and also to break antiferromagnetic (AF) magnetic symmetry, inducing ferromagnetic (FM) ordering at high temperatures. A Mn film on GaAs (100) showed FM ordering up to 9000 A with a Curie temperature (T-C) of over 750 K and a net magnetic moment of 0.33 mu(B)/Mn, instead of AF (Neel temperature, T-N=95 K) and PM orderings in bulk.