H. Miyauchi

Core-level magnetic circular dichroism in Fe7S8 and Fe7Se8

Magnetic circular dichroism (MCD) has been observed at the Fe L2,3 and M2,3 core-absorption edges in ferrimagnetic Fe7S8 and Fe7Se8 using circularly polarized helical undulator radiation. Some differences were observed between the MCD spectra of both compounds. The features of the MCD spectra are interpreted on the basis of a reported band-structure calculation.

Magnetic circular dichroism in CoS2 at the Co L2,3 and M2,3 core edges

Magnetic circular dichroism (MCD) has been observed at the Co L2,3 and M2,3 core-absorption edges in a single crystal of ferromagnetic CoS2 using circularly polarized helical undulator radiation. The features in the MCD spectra are interpreted on the basis of reported band-structure calculations. By applying the MCD sum rules to the L2,3 MCD spectrum, we obtained a ratio of the orbital-to-spin magnetic moments of 0.14.

PHOTOEMISSION MAGNETIC CIRCULAR DICHROISM STUDY OF THE FERROMAGNETIC TRANSITION-METAL OXIDE SRRUO3

Abstract The electronic structure of the ferromagnetic transition-metal oxide SrRuO3 has been studied by magnetic circular dichroism (MCD) in the valence-band photoemission spectra. MCD signals have been obtained by changing the direction of sample magnetization as well as the helicity of incident photons. Strong MCD signals were observed near the Fermi level. We have attempted to explain the MCD spectra using a band structure calculated with the unrestricted Hartree–Fock method.

Core-level magnetic circular dichroism in Co/Pt multilayers with varying Co-layer thicknesses

Abstract Magnetic circular dichroism (MCD) has been studied on Co/Pt multilayers at and around the Co M 2,3 and Pt N 6,7 and O 2,3 core-absorption edges using directly characterized circularly polarized undulator radiation. The thickness of the Co layer( t Co ) was varied between 3 – 14A with an almost constant Pt-layer thickness. We have also measured the reflectivity spectra down to 4eV and have made Kramers-Kronig analyses to obtain the dielectric tensor. The orbital magnetic moment of Co is enhanced for samples with thinner Co layers. Magnetic moments are induced on Pt atoms and ferromagnetically coupled with those on Co atoms. The Co M 2,3 MCD for samples with perpendicular magnetic anisotropy( t Co t Co > 7 A).

Magnetic circular x‐ray dichroism in Co/Pt multilayers (abstract)

A Co/Pt multilayer is one of the most attractive candidates for next‐generation high‐density magneto‐optical recording media. With a decreasing Co layer thickness, the direction of the easy axis of magnetization changes from in‐plane to out‐of‐plane. We have measured core‐level MCD of Co/Pt multilayers. Six Co/Pt multilayer samples were prepared which had Co layer thicknesses from 3 to 14 A. The MCD experiments were made using circularly polarized undulator radiation.The spectra were taken separately for the energy regions around the Co M2,3 (and Pt O3) and Pt N6,7 (and Pt O2) edges. The dichroic signals in reflectivity were recorded for two opposite directions of an external magnetic field of 2 T. We have also measured the reflectivity spectra down to 4 eV and have made Kramers–Kronig analyses to obtain the dielectric tensor. The dielectric tensor element which represents absorption MCD shows a dramatic change at the Co M2,3 edges. The MCD spectra of thinner Co‐layer samples are more asymmetric than thos...

Optical Spectra of Y3Fe5O12 (YIG) in the Y3+ 4p Core Excitation Region

Reflectivity spectrum of YIG was measured at room temperature in the Y 3+ 4p core excitation region. The optical constants are obtained by a multi-angle method. Two broad spectral bands at 29.3 and 33.3 eV and five small structures at 20.2, 22.5, 27.3, 36.5 and 40 eV were newly found in e 2 spectrum. The spectral structures are assigned; the large spectral band at 33.3 eV is made up of two transitions from Y 4p 6 1 S 0 to Y 4p 5 5s 1 (3/2, 1/2), (1/2, 1/2), where the first member in the parenthesis indicates the total angular momentum j of hole and second specifies j of electron, the structure 29.3 eV is made of a transition to Y 4p 5 4d 1 1 P 1 . In YIG the energy positions of Y 4p 5 5s 1 (3/2, 1/2), (1/2, 1/2) are about same in Y 3+ free ion, but Y 4p 5 4d 1 1 P 1 is shifted by 5.7 eV.

A compact molecular-beam epitaxy apparatus for in situ soft X-ray magnetic circular dichroism experiments

An economical and easily movable molecular-beam epitaxy (MBE) apparatus which prepares magnetic ultrathin films and superlattices with atomically well controlled interfaces has been designed and constructed. Cleaning and characterization of substrates, sample deposition in a layer-by-layer fashion, and characterization of samples both during and after growth can be carried out in a single ultrahigh vacuum (UHV) chamber. This MBE apparatus is combined with UHV high-field magneto-optical instruments for in situ soft X-ray magnetic circular dichroism experiments on two-dimensional magnetic systems.

Magnetic circular dichroism of excitons in KI and RbI

The magnetic circular dichroism spectra of KI and RbI have been measured with the reflection method at 30 K as well as at room temperature in the energy region from 5 to 9.5 eV. Accurate effective g values (geff) of excitons were determined on the basis of the rigid-shift model. The relation between the obtained values of geff and the band structure is discussed in terms of the tight-binding model.

Magnetic circular dichroism study of KBr and RbBr excitons

The magnetic circular dichroism (MCD) spectra in the exciton region of KBr and RbBr were measured for the first time utilizing an ultrahigh-vacuum compatible superconducting magnet system. The obtained effective g values (geff) at the fundamental exciton peaks are well explained as being a spin-orbit pair at the Γ point. Negative geff values in the following higher energy regions suggest the involvement of a d-like character at related conduction bands.

Magnetic circular x‐ray dichroism in Fe7S8 and Fe7Se8 (abstract)

Magnetic circular dichroism (MCD) in core‐level absorption provides insights into the element‐specific and site‐selective magnetic states of various magnetic materials. Fe7S8 and Fe7Se8 have the pseudo‐NiAs‐type crystal structure and are ferrimagnetic below 578 and ∼450 K, respectively. We have measured MCD spectra in the Fe 2p (L2,3) and Fe 3p (M2,3) core‐level absorption of these compounds. The L2,3 MCD spectra were taken at ∼80 K with the total electron yield method. The M2,3 MCD spectra were measured at room temperature with the reflection method using the magnetic‐field modulation technique. Both experiments were made using circularly polarized undulator radiation. The L2,3 MCD spectra were found to exhibit a negative peak at the L3 edge with a maximum intensity of ∼10−2 and a weaker positive peak at the L2 edge. The MCD spectrum of Fe7S8 showed sideband features near the L3 edge. Utilization of the magnetic‐field modulation method allowed a detection of small MCD signals around the M2,3 edges; the m...