Search

The electronic structures of four Laves phase iron compounds (e.g. YFe 2 , ZrFe 2 , LuFe 2 and HfFe 2 ) have been calculated with a state-of-the-art full potential electronic structure code. Our theoretical work predicted that the magnetic moments collapse under hydrostatic pressure. This feature is found to be universal in these materials. Its electronic origin is provided by the sharp peaks in the density of states near the Fermi level. It is shown that a first order quantum phase transition can be expected under pressure in Y(Zr, or Lu)Fe 2 , while a second order one in HfFe 2 . The bonding characteristics are discussed to elucidate the equilibrium lattice constant variation. The large spontaneous volume magnetostriction gives one of the most important characteristics of these compounds. Invar anomalies in these compounds can be partly explained by the current work when the fast continuous magnetic moment decrease with the decrease of the lattice constant was properly considered. This work may be as a first insight into the rich world of quantum phase transition and Invar mechanism in these Laves phase compounds. [ABSTRACT FROM AUTHOR]

Abstract: Phonon dispersions of were calculated by small displacement methods using density functional theory where the exchange-correlation potential was approximated by the general gradient approximation. Magneto-volume coupling coefficient was estimated to be . The phonon dispersions were in good agreement with the experimental data. Results showed that the dispersions were quite sensitive to the magnetic moment. The phonon frequency along became negative when the system was spin polarized. The softening of the phonon was attributed to the high density of states at the Fermi level. Our results indicate the importance of taking magnetization into account when the equation of states of are to be established. [Copyright &y& Elsevier]

Abstract: Hexagonal barium ferrites were deposited onto sapphire substrates by radio frequency magnetron sputtering. The composition, microstructure, and magnetic properties of these isotropic thin films were investigated with Rutherford backscattering spectroscopy, X-ray diffraction, atomic force microscopy, magnetic force microscopy and SQUID magnetometry. The intrinsic coercivity of the films reaches about 11.5kOe at room temperature. The mechanism of the coercivity is proposed to be nucleation in the decoupled single domain nanometer particles as shown by the characteristics of the magnetic domains and the virgin magnetization curves. [Copyright &y& Elsevier]

In this paper, magnetostrictive thick films are prepared by screen-printing and sintering. The morphology, magnetic character and magnetostriction prepared at different temperatures are studied. Characteristics of composite films thus prepared are compared with the original magnetostrictive blocks. [Copyright &y& Elsevier]

• Distribution of induced microwave current in Py film depends on its geometry. • SRE signal can be neglected at specific magnetic field angle and geometry for Py film. • Pure ISHE signal can be obtained directly in Py(20 nm)/Ta(10 nm) bilayer (40 μm × 8 mm). • Spin Hall angle value of Ta in Py/Ta bilayer is similar to that of some literatures. We present a method to directly obtain the pure inverse spin Hall effect (ISHE) signal without the spin rectification effect (SRE) signal in ferromagnetic metal(FM)/nonmagnetic metal(NM) bilayers. This method is based on a fact that the distribution of the induced microwave current is largely dependent on the geometries of the samples. The ISHE signal can be maximized through shaping the samples and tuning the magnetic field directions, while the SRE signal can be minimized below the detection limit. This provides also a fast and simplified method to measure the ISHE signal in a wide frequency range. The spin Hall angle of Ta in a Py/Ta bilayer is −0.027 ± 0.015 in a wide frequency range. [ABSTRACT FROM AUTHOR]

• Anisotropical diffusion of incident atoms leads to non-uniform thickness of films. • Films on pyramid substrates have smaller M s but larger H c than that of on flat substrate. • Coercivities of all the films on mono-like cast silicons are highly angular dependent. • Surface structure of substrates dominantly affects the magnetic properties of films. The microstructure and magnetic properties of Ta/Ni 81 Fe 19 /Ta tri-layer thin films on three types of mono-like cast silicon substrates (flat, upright pyramid and inverted pyramid surfaces) were investigated. Results show that the surface topography structures of the films followed those of the substrates generally. But the thickness of the film on pyramid surface increases from the pyramid tip to the bottom. This is caused by the anisotropical diffusion of incident atoms/ions on the pyramid surfaces during the film growth process. The films on pyramid structured substrates have smaller saturation magnetizations but larger in-plane coercivity than that of on the flat substrate. This should be mainly caused by the non-zero angle between the magnetic field and the substrates as suggested by the angular dependent magnetic properties of the films. The hysteresis loops measured from in-plane to out-of-plane directions show that the coercivities of films on all the mono-like cast silicons are highly angular dependent. A further post-annealing of the films suggests that the magnetic properties of the films are dominantly determined by the surface microstructure of substrates instead of the fabrication conditions. The above results can help better integration of NiFe thin films on mono-like cast silicon based devices. [ABSTRACT FROM AUTHOR]