Dielectric tensor for magneto-optic NiMnSb

Applied Physics Letters, 2004

Magnetic and magnetocaloric properties of the new rare-earth-transition-metal intermetallic compound Gd3Co29Ge4B10 J. Appl. Phys. 111, 07E333 A less expensive NiMnGa based Heusler alloy for magnetic refrigeration J. Appl. Phys. 111, 07A923 Oscillation of the magnetic moment in modulated martensites in Ni2MnGa studied by ab initio calculations Appl. Phys. Lett. 100, 084106 Structure and exchange bias of Ni50Mn37Sn13 ribbons

Applied Physics Letters, 2008

We report time resolved magneto-optical measurements in InMnSb ferromagnetic films with 2% and 2.8% Mn contents grown by low temperature molecular beam epitaxy. In order to probe a possible interaction between the spins of photoexcited carriers and the Mn ions, we measured spin dynamics before and after aligning the Mn ions by applying an external magnetic field at temperatures above and below the samples’ Curie temperatures. We observed no significant temperature or magnetic field dependence in the relaxation times and attribute the observed dynamics entirely to the relaxation of photoexcited electrons in the conduction band where the s-d coupling with the localized Mn ions is significantly weaker compared to the p-d exchange coupling. We observed several differences in the optical response of our InMnSb samples which could have been influenced mainly by the samples’ growth conditions.

Physical Review B, 2004

The point contact Andreev reflection employing niobium tips was used to determine the degree of transport current spin polarization ͑P t ͒ at the free surface of bulk NiMnSb at 4.2 K. The data was analyzed within the framework of a modified version of the Blonder, Tinkham, and Klapwijk formulism taking into account the two spin polarized channels in the ferromagnet and treating the interface as a planar delta function barrier of height Z between free electron materials. We find that the measured spin polarization is rather insensitive to different surface preparations and magnetic domain structure, and the maximal value of the P t at Z = 0 is 44%, consistent with recent calculations of the surface reconstruction of NiMnSb. Saturation magnetization of the samples was found to be 3.6 B per formula unit indicative of a small amount of atomic disorder.

physica status solidi c

In present work, our research is mainly focused on the electronic structures, optical, and magnetic properties of XMnSb (X = Ni, Cu, Pd), Co2YZ (Y = Ti; Z=Si, Ge, Sn), and Co2YZ (Y =Mn; Z=Al, Ga, Si) Heusler compounds by using ab initio calculations within the generalized gradient approximation. The calculations are performed by using the Vienna ab initio simulation package based on the density functional theory. The band structure of these Heusler alloys for majority spin and minority spin were calculated and the majority spin states cross the Fermi level and thus have the metallic character, while the minority spin states open the band gaps around the Fermi level and thus have the narrow‐band semiconducting nature. We also find that these Heusler compounds have the indirect band gaps in the minority spin channel. The real and imaginary parts of dielectric functions and hence the optical functions such as energy‐loss function, the effective number of valance electrons and the effec...

physica status solidi (a), 2007

In this study we investigated the magneto-transport properties of the ohmic contact between polycrystalline NiMnSb thin films grown by pulsed laser deposition and n-type degenerate InSb (100) substrates. An unusual negative giant magnetoresistance (n-GMR) effect is found when the external magnetic field is parallel to the in-plane current direction. A similar effect is also observed when Ni films are deposited on InSb substrates. On the other hand, no n-GMR effect is displayed when the deposited film is nonmagnetic. Grazing-incidence X-ray reflectometry shows the formation of a low-density NiMnSb layer at the interface. The presence of such a layer coincides with the appearance of the n-GMR.We argue that the n-GMR effect is due to magnetic precipitates formed at the interface during the growth of the magnetic films. We propose that these precipitates align their magnetic moments in the direction of the external magnetic field and thus, the spin dependent scattering of the electrons is reduced. The effect of these precipitates on the magnetoresistance depends on the thermal processing of the system.

Physical Review B, 1997

The magneto-optical ͑MO͒ spectra of 15 ternary ferromagnetic compounds are investigated on the basis of local-density band-structure calculations. The key material of interest in this study is PtMnSb, for which the MO Kerr spectra are unusually large and quite different from that of, e.g., the isoelectronic compounds NiMnSb and PdMnSb. First we show that the spectral differences between NiMnSb, PdMnSb, and PtMnSb can be fully understood from their relativistic electronic structure. Further, we investigate the following ternary ferromagnetic compounds: PtMnSn, PtCrSb, PtFeSb, Pt 2 MnSb, Co 2 HfSn, NiMnAs, PdMnAs, PtMnAs, RuMnAs, PtMnBi, BiMnPt, and PtGdBi. Within the total group of alloys, we study the MO spectra of PtMnSb in relationship to the spin-orbit coupling strength; the magnitude of the 3d-magnetic moment; the degree of hybridization in the bonding; the half-metallic character, or, equivalently, the Fermi-level filling of the band structure; the intraband plasma frequency; and the influence of the crystal structure. We find that these characteristics form a unique combination in PtMnSb leading to its outstanding MO Kerr spectra. None of the other compounds can match up to PtMnSb in this respect. For the compounds NiMnAs, PdMnAs, PtMnAs, and, particularly, RuMnAs, whose MO spectra are not measured as yet, we predict Kerr spectra which look promising for ultraviolet laser light recording applications.

Journal of Applied Physics, 2004

NiMnSb half Heusler alloy films were prepared by molecular beam epitaxy ͑MBE͒ on InP͑001͒. The dc and rf magnetic properties were investigated by ferromagnetic resonance ͑FMR͒. The effective uniaxial anisotropy fields increased with increasing film thickness and reached nonzero asymptotic values. FMR linewidths rapidly increased with the film thickness due to the presence of two magnon scattering. Bulklike uniaxial anisotropies and two magnon scattering were caused by a self-assembled network of lattice defects. Gilbert damping parameter and spectroscopic g factor were found to be 3.1ϫ10 7 and 2.03, respectively, indicating a weak role of spin orbit interaction.

The magneto-optical ͑MO͒ spectra of 15 ternary ferromagnetic compounds are investigated on the basis of local-density band-structure calculations. The key material of interest in this study is PtMnSb, for which the MO Kerr spectra are unusually large and quite different from that of, e.g., the isoelectronic compounds NiMnSb and PdMnSb. First we show that the spectral differences between NiMnSb, PdMnSb, and PtMnSb can be fully understood from their relativistic electronic structure. Further, we investigate the following ternary ferromagnetic compounds: PtMnSn, PtCrSb, PtFeSb, Pt 2 MnSb, Co 2 HfSn, NiMnAs, PdMnAs, PtMnAs, RuMnAs, PtMnBi, BiMnPt, and PtGdBi. Within the total group of alloys, we study the MO spectra of PtMnSb in relationship to the spin-orbit coupling strength; the magnitude of the 3d-magnetic moment; the degree of hybridization in the bonding; the half-metallic character, or, equivalently, the Fermi-level filling of the band structure; the intraband plasma frequency; and the influence of the crystal structure. We find that these characteristics form a unique combination in PtMnSb leading to its outstanding MO Kerr spectra. None of the other compounds can match up to PtMnSb in this respect. For the compounds NiMnAs, PdMnAs, PtMnAs, and, particularly, RuMnAs, whose MO spectra are not measured as yet, we predict Kerr spectra which look promising for ultraviolet laser light recording applications.

Journal of Magnetism and Magnetic Materials, 2005

Andreev reflection in point contacts between a ferromagnet and a superconductor has been developed in recent years as a method to measure the degree of spin polarization P of the ferromagnet. We have developed the method for planar thin-film edge contacts prepared by a seven-step process. Measurements of the conductance of an Nb/Cu edge junction showed the expected doubling of conductance for bias levels in the range 71.1 mV, corresponding to the superconducting energy gap of the Nb film ðT SC ¼ 6:5 KÞ: For Ni, however, the conductance falls to 20% of its normal value within the energy gap. A fit of the data gives P ¼ 70%; which is much greater than the currently accepted value of 46%. Possible explanations for the elevated spin polarization in these planar junctions are d-band narrowing and electron transfer to incorporated oxygen. r

Polarized neutron diffraction on NiMnSb shows a weak polarization on Ni parallel to the Mn moment, and a slight change in structure factors near 80 K which may be related to the loss of half-metallic character.