Kenji Obu

Photoemission Study of 4f Electronic States in PrFe4P12 and Related Pr Compounds

We have measured the Pr 4 d –4 f high-resolution resonant photoemission and the Pr 3 d core-level photoemission spectra of PrFe 4 P 12 and related compounds PrSn 3 , PrAl 2 and Pr metal. The Pr 4 f...

Local magnetic susceptibility in rare-earth compounds

The element specific magnetic susceptibilities of some rare-earth compounds are estimated by measuring magnetic circular dichroism at rare-earth M 4,5 absorption edges. The temperature dependences ...

Magnetic circular dichroism of X-ray emission for gadolinium in 4d-4f excitation region

We have measured magnetic circular dichroism of x-ray emission spectra (XES) for gadolinium in the 4 d –4 f excitation region. At a pre-threshold excitation energy, a large magnetic circular dichroism (MCD) signal appeared in a Raman scattering and the dramatic dependence of the MCD spectra on the excitation energy was observed. Theoretical calculation shows that the magnetic moment estimated with total photoelectron yield (TEY) spectra was much smaller than that with the emission spectra. This indicates that the MCD for the TEY reflects the magnetic state on the surface whereas the MCD for the XES reflects that in the bulk. We also observed the MCD spectra for total photon yield (TPY) and found the great difference of the MCD spectra for the TEY and TPY.

MCD Study on Materials without Magnetic Order

Core excited magnetic circular dichroism (MCD) signals have been measured on PrFe 4 P 12 and CePd 3 under the states without magnetic order. The inverse values of the MCD magnitudes have been plott...

RESONANT PHOTOEMISSION STUDY OF RFe4P12 (R = La, Ce, Pr)

We have measured the 4d–4f high-resolution resonant photoemission spectra of RFe4P12 (R = La, Ce, Pr), PrSn3 and PrAl2. The Ce and Pr 4f spectra show the spectral features corresponding to a strongly hybridized system. However, the

Measurements of temperature dependence of localized susceptibility

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MAGNETIC CIRCULAR DICHROISM OF 4d–4f RESONANT X-RAY EMISSION FOR GADOLINIUM AND TERBIUM

and the 3H4 peaks located just below the Fermi energy in the Ce 4f and Pr 4f spectra, respectively, are observed as a shoulder instead of the prominent peak expected for the strongly hybridized or high-Kondo temperature systems.

Measurement of the two-photon correlation of synchrotron radiation in the VUV region by a delay-time modulation technique.

Abstract The magnetic susceptibility of some rare-earth compounds is estimated by measuring magnetic circular dichroism (MCD) of rare-earth 3d–4f absorption spectra. The temperature dependence of the magnetic susceptibility obtained by the MCD measurement is remarkably different from the bulk susceptibility in most samples, which is attributed to the strong site selectivity of the core MCD measurement.

MEASUREMENT OF THE SECOND-ORDER COHERENCE OF SYNCHROTRON RADIATION IN THE VUV REGION

We have measured the magnetic circular dichroism (MCD) of X-ray emission spectra (XES) for gadolinium and terbium in the 4d–4f resonant excitation region. Clear MCD signals in the XES were observed and they dramatically changed as the excitation energy changed. Especially, an extremely large MCD signal appeared with the 8D resonant excitation for gadolinium. Comparison between the MCD for XES and total photoelectron yield (TEY) shows that the XES are very insensitive to the surface state. As a result, the measurement of XES was proved to be a superior technique for estimating the genuine magnetic moment in the bulk.

Resonant photoemission study of CeRu4Sb12

The two-photon correlation (second-order coherence) of synchrotron radiation in the VUV region (hnu = 55 eV) has been measured using a novel photon-counting method. A new technique has been developed to measure a small bunching effect by using a coincidence unit composed of a constant fraction discriminator, a time-to-amplitude converter (TAC), a single-channel analyzer (SCA) and two solid-state switches. The path of the circuit through which the stop signal for the TAC passes can be changed by a control voltage generated by a function generator, and the relative arrival time of two photons on condition that the output signal from the SCA appears is consequently changed. By modulating the arrival time and measuring the output rate from the SCA with a digital lock-in amplifier, an apparent bunching effect has been observed which is characteristic of the chaotic light. The electron-beam emittance in the horizontal direction was estimated as 39(-8)(+13) nm rad by this experiment, and the value was consistent with the designed value of 36 nm rad.