Electronic Structure of La(Fe0.88Si0.12)13
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1262-W06-03
Electronic Structure of La(Fe0.88Si0.12)13 Nozomu Kamakura 1, Tetsuo Okane 1, Yukiharu Takeda 1, Shin-ichi Fujimori 1, Yuji Saitoh 1, Hiroshi Yamagami 1,2, Atsushi Fujimori 1,3, Asaya Fujita 4, Shun Fujieda 5, Kazuaki Fukamichi 5 1
Synchrotron Radiation Research Center, Japan Atomic Energy Agency, Hyogo 679-5148, Japan 2 Department of Physics, Kyoto Sangyo University, Kyoto 603-8555, Japan 3 Department of Physics, University of Tokyo, Tokyo 113-0033, Japan 4 Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan 5 Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan ABSTRACT La(Fe0.88Si0.12)13 shows peculiar magnetic properties such as the first order paramagneticferromagnetic transition and magnetic-field induced metamagnetic transition accompanied by the lattice expansion. The practical application using the magnetic transition temperature controlled by hydrogen absorption is expected in this compound. Here, the electronic structure of La(Fe0.88Si0.12)13 has been investigated by photoemission spectroscopy using synchrotron soft xrays. The Fe 3s core-level photoemission spectra below and above the Curie temperature TC exhibit a satellite structure at ~ 4.3 eV higher binding energy than the main peak, which is attributed to the exchange splitting due to the local moment of Fe. The exchange splitting of the Fe 3s photoemission spectrum with the asymmetric line shape shows that the magnetization of La(Fe0.88Si0.12)13 is derived by the exchange split Fe 3d bands like the itinerant ferromagnetism in Fe metal, while the magnetic transition of La(Fe0.88Si0.12)13 is the first order. The valence band photoemission spectrum shows temperature dependence across the TC. The temperature dependence of the photoemission spectra is discussed based on the difference between the electronic structure in the ferromagnetic phase and that in the paramagnetic phase. INTRODUCTION La(FexSi1-x)13 shows a variety of magnetic properties depending on the composition [1-9]. The ferromagnetic state is stabilized in a wide range of Fe content. With increasing Fe content, the Curie temperature TC decreases and the ferromagnetic transition changes from a second order to a first order at x = 0.86. In the composition x > 0.86, the magnetic field-induced metamagnetic transition takes place between the critical temperature T0 and the TC. Characteristic of La(FexSi1x)13 is to absorb hydrogen. The lattice expansion by hydrogen absorption in La(FexSi1-x)13 increases the TC up to room temperature [7-9]. The magnetic transition involving the lattice expansion enables one to apply La(FexSi1-x)13Hy to large magnetostrictive materials and magnetic refrigerator using magnetocaloric effect that can be controlled around room temperature. In this study, the electronic structure of La(FexSi1-x)13 across the first order magnetic transition is investigated by photoemission spectroscopy. Since the first order magnetic transition maintains even after th
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