Papers by Keyword: Ferromagnet

Abstract: In the summer school of PSD2024, focusing on spin-polarized positron annihilation spectroscopy in materials science, I reported the historical background and its possibility concerning current spintronics field, the basic principles, and prospects. Here, as a memorandum, I mainly summarize the basic principles, which can be relatively well-formulated, with some remarks.

Abstract: We have systematically investigated the dynamic susceptibility spectra of square-patterned ferromagnets in the mesoscopic scale from 100 nm to 500 nm by means of a micromagnetic simulation. The dynamic susceptibility spectra are obtained from the magnetization response under the applied field using Fourier transforms technique. We have observed that the frequency peak of the susceptibility spectra slightly increases as the length of the square-patterned increases. Interestingly, the frequency peak shows similar behavior compared to the frequency resonance from Kittel’s formula. We have also analyzed the magnetic energies, where the demagnetization energy is larger than the exchange energy. It can be explained that the polar interaction primarily contributes to the resonance mode of the square-patterned ferromagnets

Abstract: Diffraction intensities of a single crystal of Fe₃Pt alloy have been measured by using white X-rays of synchrotron radiation. The observed intensities have been compared with the calculated ones for fundamental and superlattice reflections. By normalizing the calculated intensities of fundamental reflections to the observed ones and evaluating the ratio of the observed intensity of superlattice reflection to the calculated ones, we have estimated the order parameter as 0.82±0.03. The obtained order parameter has been applied to an analysis of the X-ray magnetic diffraction data to estimate the spin moment of Fe and Pt atoms in this alloy.

Abstract: We have performed X-ray magnetic diffraction experiments of a ferromagnetic binary alloy Fe₃Pt in order phase, and have measured separately spin and orbital magnetic form factors. By a curve-fitting analysis in which atomic-model form factors of Fe-3d and Pt-5d electrons under the dipole approximation are assumed, we have obtained the spin and orbital magnetic moments of Fe and Pt atoms separately. The present result is comparable to those of other experimental and theoretical studies, which shows the validity of this experimental method.

Abstract: An experimental method of X-ray magnetic diffraction was applied to the ferromagnetic rare-earth compound CeRh₃B₂, and its spin and orbital magnetic form factors were measured independently for the first time. Our curve-fitting analysis shows that the orbital magnetic form factor is reproduced by the calculated atomic-model form factor of Ce-4f electrons under the dipole approximation. The comparison of the sum of form factors and the total magnetic form factor measured by the polarized neutron diffraction reveals anisotropic distribution of the magnetic moment in real space.

Abstract: New pseudo-hollandite chromium tellurides, ACr5Te8 (A = K, Cs and Rb), have been synthesized. KCr5Te8 is isostructural (type-A; space group C2/m) to ACr5S8, while RbCr5Te8 and CsCr5Te8 crystallize in a different structure (type-B; space group C2/m). All compounds show ferromagnetic transition, in contrast to antiferromagnetic transition in pseudo-hollandite chromium sulfides and selenides. The ferromagnetism of ACr5Te8 would be related to long Cr-Cr distances, band structure or itinerancy.

Abstract: Two types of magnetoresistive effects can be observed in the multilayer structure of the ferromagnet/polydiphenylenephthalide/non-magnetic metal. One can see the effect of resistance switching in an external magnetic field and also the angular magnetoresistive dependence. The similarities and differences of these effects and other known magnetoresistive effects are considered. The conclusion is drawn that the peculiarities of the magnetoresistance in the ferromagnetic-polymer system are formed in the ferromagnet-polymer interface and the special features of charge injection into the conductive nanoscale channels of the polymer film have the determinative importance.

Abstract: An　X-ray magnetic diffraction (XMD) is applied to ferromagnetic transition metal oxide YTiO₃. The spin magnetic form factors are measured for 81 reciprocal lattice points of h0l, hk0 and 0kl series. Three-dimensional spin density distribution in the real space of YTiO₃ is successfully obtained by using Maximum Entropy Method (MEM). This is the first result of spin density in the real space by the XMD.

Abstract: We have measured spin and orbital magnetic form factors of Pd3Co for various reciprocal lattice points by the X-ray magnetic diffraction. Observed spin and orbital magnetic form factors are fitted by theoretical curves of the isolated atomic model under the dipole approximation. By the fitting analysis we have evaluated separately the spin and orbital component of the magnetic moment of Pd3Co alloy as 2.19 µB/f.u. and 0.83 µB/f.u., respectively. The total magnetic moment 3.02 µB/f.u. is comparable to the value of 2.93 µB/f.u. obtained by the magnetization measurement.

Abstract: In the present paper the dispersive equation for surface polaritons localized at the ferromagnet - high temperature superconductor interface structure have been obtained. The main characteristics dependences upon the external magnetic field are analyzed in the frame of the electromagnetic approach for transverse electric (TE) polarization wave. The analysis for different orientations of superconductor crystallographic axes relative to wave vector directions is carried out.