2013年12月23日（周一）上午10:30，物理系seminar：

報告題目： Unified model for spin order induced polarization in multiferroicsUnified model for spin order induced polarization in multiferroics 報告人：向紅軍教授, Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, People’s Republic of China 報告時間： 2013-12-23 10:30 報告地點：理科樓三樓報告廳摘要： In recent years, we have theoretically studied the microscopic origin of ferroelectricity in different multiferroic systems. We proposed a unified model [1,2], which includes purely electronic and ion-displacement contribution simultaneously to describe spin-order induced ferroelectricity. An efficient method [3] was developed to compute the model parameters from first-principles. On the basis of the unified model and density functional calculations, we explained the ferroelectricity induced by the proper-screw spin spiral [2], discovered a novel magnetoelectric coupling mechanism in which the magnitude of the polarization is governed by the exchange striction with the direction by the spin chirality [4], proposed that the ferroelectricity in the chiral-lattice magnet Cu2OSeO3 is due to the unusual single-spin site term [5], unraveled that the magnetoelectric effect observed in BiFeO3 originates from the exchange striction [2].
References
1. H. J. Xiang, E. J. Kan, Y. Zhang, M.-H. Whangbo, and X. G. Gong, Phys. Rev. Lett. 107, 157202 (2011).
2. H. J. Xiang, P. S. Wang, M.-H. Whangbo, and X. G. Gong, Phys. Rev. B 88, 054404 (2013).
3. H. J. Xiang, E. J. Kan, Su-Huai Wei, M.-H. Whangbo, and X. G. Gong, Phys. Rev. B 84, 224429 (2011).
4. X. Z. Lu, M.-H. Whangbo, Shuai Dong, X. G. Gong, and H. J. Xiang, Phys. Rev. Lett. 108, 187204 (2012).
5. J. H. Yang, Z. L. Li, X. Z. Lu, M.-H. Whangbo, Su-Huai Wei, X. G. Gong, and H. J. Xiang, Phys. Rev. Lett. 109, 107203 (2012). 報告人簡介：向紅軍現為複旦大學物理系、應用表面物理重點實驗室、物質計算科學教育部重點實驗室教授。1997年9月至2006年7月就讀于中國科學技術大學化學物理系，并獲本科和博士學位。2006年9月至2009年底，分别在美國北卡州立大學和美國可再生能源國家實驗室開展博士後研究。向紅軍長期從事計算凝聚态物理研究，主要開展計算方法的發展，結構和性質的預言和設計，模型計算等。特别地，在多鐵性微觀機制方面取得了進展：提出了自旋序誘導鐵電性的普适性極化模型，并發展了相應的第一性原理計算方法；利用普适性極化模型解釋了以前理論不能理解的多種複雜氧化物體系的多鐵現象。其博士論文“納米材料的理論研究及線性标度電子結構方法的發展”曾獲2008年全國百篇優秀博士論文獎，2009年被授予上海高校特聘教授（東方學者）稱号，2010年被評為教育部新世紀優秀人才。迄今發表SCI論文80多篇，其中Phys. Rev. Lett. 16篇。