Magnetic Properties And Dipolar Interactions Of Magnetic Nanoparticle Systems

Magnetic nanoparticles have received considerable interests, due to both their important potential applications and their rich experimental behaviors in physics. In this thesis, interested in both the preparations and the dipolar interactions of the magnetic nanoparticle assembly, we focused more on the investigation of the latter.We firstly studied the magnetic properties of the Fe-implanted MgO samples. Single crystals of MgO with (100), (110) and (111) orientations were implanted with Fe ions at high dose by using metal-vapor vacuum arc ion source (MEVVA). The magnetic properties were investigated by a superconducting quantum interference device magnetometer (SQUID) and Rutherford backscattering spectrometry (RBS) was used to analyze the Fe concentration and distribution. The presence and the wide size distribution of magnetic nanoparticles in MgO matrix was verified by magnetization measurements. Results show that all the samples behave as ferromagnetism at 5K and 300K, and the coercive field, HC, well follows the relation: HC(110)