WANG Xiao-Xiong1,2, LI Hong-Nian1, XU Ya-Bo1, WANG1, ZHANG Wen-Hua3, XU Fa-Qiang3
1Department of Physics, Zhejiang University, Hangzhou 3100272College of Science, Nanjing University of Science and Technology, Nanjing 2100943National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029
Electronic Structure of Eu6C60
WANG Xiao-Xiong1,2, LI Hong-Nian1, XU Ya-Bo1, WANG1, ZHANG Wen-Hua3, XU Fa-Qiang3
1Department of Physics, Zhejiang University, Hangzhou 3100272College of Science, Nanjing University of Science and Technology, Nanjing 2100943National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029
摘要We study the valence band of Eu-intercalated C60 by synchrotron radiation photoelectron spectroscopy to understand the ferromagnetism (FM) and the giant magnetoresistance (GMR) of Eu6C60. The results reveal the semiconducting property and the remarkable 5d6s-π hybridization. Eu-C60 bonding has both ionic and covalent contributions. No more than half the 5d6s electrons transfer from Eu to the LUMO derived band of C60, and the LUMO+1 derived band is not filled. The remaining valence electrons of Eu, together with some π (LUMO, HOMO and HOMO-1) electrons, constitute the covalent bond. The electronic structure implies that the magnetic coupling in Eu6C60 should be through the intra-atomic f-sd exchange and the medium of the π electrons. The possibility of the GMR being tunnelling agnetoresistance is ruled out
Abstract：We study the valence band of Eu-intercalated C60 by synchrotron radiation photoelectron spectroscopy to understand the ferromagnetism (FM) and the giant magnetoresistance (GMR) of Eu6C60. The results reveal the semiconducting property and the remarkable 5d6s-π hybridization. Eu-C60 bonding has both ionic and covalent contributions. No more than half the 5d6s electrons transfer from Eu to the LUMO derived band of C60, and the LUMO+1 derived band is not filled. The remaining valence electrons of Eu, together with some π (LUMO, HOMO and HOMO-1) electrons, constitute the covalent bond. The electronic structure implies that the magnetic coupling in Eu6C60 should be through the intra-atomic f-sd exchange and the medium of the π electrons. The possibility of the GMR being tunnelling agnetoresistance is ruled out
[1] Ksari-Habiles Y et al 1997 J. Phys. Chem. Solids 58 1771 [2] Ishii K, Fujiwara A, Suematsu H and Kubozono Y 2002 Phys. Rev. B 65 134431 [3] Takenobu T et al 2003 J. Am. Chem. Soc. 1251897 [4] Zhu L, Yao K L and Liu Z L 2007 Solid State Commun. 141 628 [5] Wu J et al 1992 Physica C 197 251 [6] He S et al 2007 J. Phys.: Condens. Matter 19026202 [7] Yoshikawa H et al 1995 Chem. Phys. Lett. 239103 [8] Tjeng L H et al 1997 Solid State Commun. 10331 [9] Wang X X, Li H N and Xu Y B 2008 Solid State Commun. 147 436 [10] Wang X X, Li H N, Zhang W H and Xu F Q 2007 J.Phys.: Condens. Matter 19 096001 [11] Li H N, Wang X X and Ding W F 2006 J. ElectronSpectrosc. Relat. Phenom. 153 96 [12] Claves D, Ksari-Habiles Y, Chouteau G and Touzain Ph 1998 Solid State Commun. 106 431 [13] Yeh J J and Lindau I 1985 Atomic SubshellPhotoionization Cross Section and Asymmetry Parameters: $1\le Z\le103$ (New York: Academic) pp 7--11 [14] He S L et al 2005 Phys. Rev. B 71 085404 [15] Wang X X et al 2006 Acta Phys. Sin. 55 4265(in Chinese) [16] Wertheim G K, Buchanan D N E and Rowe J E 1992 Science 258 1638 [17] Knupfer M, Stepniak F and Weaver J H 1994 Phys.Rev. B 49 7620 [18] Satpathy S et al 1992 Phys. Rev. B 46 1773 [19] Hoogenboom B W, Hesper R, Tjeng L H and Sawatzky G A 1998 Phys. Rev. B 57 11939 [20] Tsuei K D et al 1997 Phys. Rev. B 56 15412 [21] Li H N et al 2005 Surf. Sci. 586 65 [22] Kune\v{s J and Laskowski R 2004 Phys. Rev. B 70 174415
2009, Vol. 26 
