45 research outputs found
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
Interface effects on the magnetic properties of exchange coupled Co/Fe multilayers studied by Brillouin light scattering
Magnetic and transport polaron percolation in diluted GeMn films.
Magnetic and electronic transport properties of Mn-doped Ge films have been studied as a function of Mn content. The films exhibit a long-range ferromagnetic behavior and a Mn dilution-dependent Curie temperature TC . Resistivity shows an insulator-like character with two distinct activation energies below about 80 K, while the Hall coefficient evidences a strong contribution from the anomalous Hall effect, in a p-type material. At a characteristic temperature TR, resistivity experiences a sudden reduction and the Hall coefficient reverses its sign from positive to negative. Moreover, around TR, any residual remanence and coercivity disappear.
The transport and magnetic results are deeply related and can be qualitatively explained by a percolation model based on bound magnetic polarons due to localized holes in the GeMn alloy lattice