Structural and magnetic characterizations of Mn_2CrO_4 and MnCr-2O_4 films on MgO(001) and SrTiO_3(001) substrates by molecular beam epitaxy

摘要

In this report, we grow MnCr-2O_4 (124) films, and Mn_2CrO_4 (214) films, for comparison, on MgO and SrTiO_3 (STO) substrates by oxygen-plasma-assisted molecular beam epitaxy and also carry out the measurements of the magnetization as a function of temperature (5-200 K) and external field (0-5 T) of these films. The results of magnetization versus temperature further show that ferrimagnetic transition (T_c) occurs at 44 K for 214 films grown on both MgO and STO. The T_c of 124 films raises to 45 K but is only observed for the film grown on STO. No or very weak magnetization is observed for the 124 films grown on MgO(OOl). The vanishing of the magnetization of the 124 films grown on MgO is attributed to the instability of spinel structure for Cr-rich films.