Search for ferromagnetism in Mn-doped LaAlO3 single crystals

In recent years, because of the intriguing prospect of their applications in the next generation of spintronic devices, diluted magnetic semiconductors (DMSs) have stimulated intense interest, typically III-V or II-VI semiconductors exhibiting magnetic order upon doping with a few percent of magnetic elements, like Fe, Co or Mn. Search for intrinsic high Curie temperature DMSs has become a fascinating endeavor in transition metal doped wide-banded semiconducting oxides such as TiCh, CuO, ZnO, and SnO₂. On the other hand, ABO₃ perovskite oxides can show both metallic and semiconducting behavior at different temperatures. However, very little work searching for ferromagnetism has been carried out on ABO₃ perovskite oxides. In this work, LaAlO₃ single crystals were dilutely doped with magnetic transition element Mn for investigation of ferromagnetism. Mn doped LaAlO₃ single crystals were prepared by a thermal diffuse technique, which is commonly used as a flexible method by easily doping impurity into host material. In our experiments, two pieces of commercial LaAlO₃ single crystals were closely surrounded by MnO₂ powders in two crucibles. Then these two crucibles containing LaAlO₃ crystal and MnO₂ powders were annealed in air at 750°C and 1300°C respectively for 24 hours. The temperature dependence of magnetization of Mn-doped LaAlO₃ was measured using a commercial vibrating sample magnetometer (VSM) in the temperature range between 60 K and 300 K with an applied field of 500 Oe. The corresponding magnetic hysteresis (M-H) loops at different temperatures were also measured by VSM.