Magneto-optical characterization of MnxGe1-x alloys obtained by ion implantation

Magneto-optical Kerr effect hysteresis loops at various wavelengths in the visible/near-infrared range have been used to characterize the magnetic properties of alloys obtained by implanting Mn ions at fixed energy in a Ge matrix. The details of the hysteresis loops reveal the presence of multiple magnetic contributions. They may be attributed to the inhomogeneous distribution of the magnetic atoms and, in particular, to the known coexistence of diluted Mn in the Ge matrix and metallic Mn-rich nanoparticles embedded in it [Phys. Rev. B 73, 195207(2006)].Comment: 2 pages, 2 figures. Proceeding of the International Conference on Magnetism. Kyoto, August 20-25 200

Magnetic Properties of Matter

Proceedings of The National School "New Developments and Magnetism's Aplications

NEAR IR FARADAY ROTATION ON YIG DOPED WITH TETRAVALENT AND PENTAVALENT ELEMENTS

We report 300 and 4 K Faraday Rotation measurements in function of wavelength on bulk YIG doped with tetravalent (Ge, Sn, Zr) or pentavalent elements Sb. On the samples doped with octahedral localized dopage we observe spectra with maxima at 1.1, 1.45 and 2.05 µm and a strong dip at 1.75 µm. We analyse them in connection with Magnetic Circular Dichroism measurements

Influence of Cu seed layer on the magnetization reversal in exchange-biased FeMn/FeCo systems

Magnetization hysteresis loops are measured on FeMn/FeCo bilayers. The existence of the exchange bias effect up to room temperature is guaranteed by the presence of copper as a seed layer. We demonstrate that the choice of the growth parameters for Cu allows the control of the magnetic response of the structure, tuning the coercivity and the exchange field. The switching field distribution suggests different magnetization reversal mechanisms during the ascending and descending branches of the hysteresis loop. The evident noisy character of the data, during the reversal of the magnetization with respect to the initially set orientation, supports the picture of domain wall motion involving pinned states at magnetic defects, contrasting with the coherent magnetic moments rotation along the opposite branch

TEMPERATURE DEPENDENCE OF MAGNETO-OPTICAL EFFECTS ON Fe - Al2O3 GRANULAR FILMS

Faraday and Magnetic Circular Dichroism measurements in the region of near infrared are performed in the temperature range 4 < T < 300 K on Fe - Al2O3 granular films. The intensities of the observed transitions, due to Fe2+ and Fe3+ ions, remain constant below characteristic temperatures depending on iron concentration and on the average particle's dimensions

Toward room temperature ferromagnetism of Ge:Mn systems

We investigate the magnetic properties of Mnx Ge1x =Ge(1 0 0) films. We show that the choice of growth temperature and Mn content is crucial for achieving optimal magnetic performance. With a substrate temperature of 160C during film deposition, and Mn concentration between 2.7% and 4.4%, hysteresis is observed up to about 250 K. However, the magnetic loop maintains a saturating behaviour at high fields up to room temperature. For larger Mn concentrations the magnetic response is strongly suppressed, suggesting a possible segregation of manganese