Crystal orientation dependence of ferromagnetism in Fe-implanted MgO single crystals

Single crystals of MgO with (100), (110) and (111) orientations were implanted with 64 keV Fe ions at a dose of 1.9×1017 ions/cm2 by using metal-vapor vacuum arc ion source (MEVVA). The magnetic properties were investigated by a superconducting quantum interference device magnetometer and Rutherford backscattering spectrometry (RBS) was used to analyze the Fe concentration and distribution. The presence of Fe nanoparticles in MgO matrix was verified by magnetization measurements. Results show that all the samples behave with ferromagnetism at 5 K and 300 K, and the coercive field, H C , follow well the relation: H C ( 110 ) < H C ( 100 ) < H C ( 111 ) at measured temperatures. The orientation dependence of the coercive field may result from the different distribution of Fe nanoparticle size.