### Isao Harada’s Visit & Talk@UPM

27Oct10

I have been informed by Dr. Mahmudur-Rahman (our new condensed matter theorist at UPM, finally) that Prof. Isao Harada will be visiting him/UPM on the 2-3 Novmber 2010. He will be giving a talk on the Nov 2, 2010 at 3pm in Lecture Room 304 besides the UPM Physics Department General Office. The talk is on “High Energy X-Ray Spectroscopy of Strongly Correlated Electron Systems”. Please help publicise this to interested colleagues and friends. We need the crowd. Below are the details:

High Energy X-Ray Spectroscopy of Strongly Correlated Electron Systems

by
Okayama University
3-2-2 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan

Time and Date: 3pm, November 2, 2010
Venue: Lecture Room 304, Physics Department, UPM

Abstract:

X-ray Absorption Spectroscopy (XAS) and Magnetic Circular Dichroism (XMCD) have become a powerful technique for studying electronic and magnetic properties of magnetic materials with the aid of a recent development of X-ray light sources. These experiments give us important information on an inner shell electron excitation to the valence electron states, which is element specified as well as shell specified. To analyze these useful data, we need a sophisticated theory for XAS and XMCD.

In this talk, I will start with an introduction of XAS and XMCD, and extend the talk to a recent progress of our study: XAS and XMCD of valence mixed systems of rare-earth compounds in high magnetic fields. Strong magnetic fields induce a valence transition, which have recently been observed in $\textrm{EuNi}_2(\textrm{Si}_{0.18}\textrm{Ge}_{0.82})_2$ at the $L$-edges of $\textrm{Eu}$. We have investigated theoretically this phenomenon based on an effective model, taking into account the hybridization between a localized $4f$ electron and an itinerant $5d$ conduction electron. As a result, we show this is a transition from the $\textrm{Eu}^{3+}$ nonmagnetic phase to the $\textrm{Eu}^{2+}$ magnetic phase controlled by high magnetic fields.

Professor Dr. Isao Harada received his B.Sc.in physics, M.Sc. and Ph.D. in theoretical condensed matter physics from Osaka University in 1967, 1969 and 1972 respectively. He started his career as an Assistant Professor in Kobe University. He moved to Okayama University in 1990 to be an Associate Professor before taking up an appointment as a Professor in Okayama University. He has retired in March 2010, and is a Professor Emeritus as well as the Director of the Educational Center for Science in Okayama University. He was also a Visiting Assistant Professor at Ohio University in 1977-1978, Research Associate (RA) at Honnover University in 1987-1988, RA at Hahn-Meitner Institute, Berlin in 2001, Visiting Professor (VP) at the University of Louis Pasteur in Strasbourg in 2007, and VP at the University of Cergy-Pontoise in Paris in 2009.

The scientific activity of Prof. Harada covers the fields of theoretical condensed matter physics including the statistical physics for low-dimensional quantum spin systems, the surface science of magnetic materials, nonlinear excitation, soliton, one-dimensional magnets, and high energy spectroscopy of magnetic materials. He has been always interested not only in mathematical formulation of physics but also in applications of mathematical models to real substances. Of notable contribution is his excellent theoretical contribution to the magnetic circular dichroism for magnetic materials in high magnetic fields. Recently, his interests are also focused on the education of natural sciences for young students. For instance, he was a leader of the Japan-team for International Physics Olympiad and has tried to establish a new concept of scientific education for talented young students.

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