Title：Spin-dependent Band Structure and Unusual Hall Effect in the Ferromagnetic Semimetal EuB₆

Date：August 5, 2008

By：Prof. Peng Xiong (熊鹏) (Department of Physics and Center for Materials Research and Technology, Florida State University, USA)

Abstract:EuB₆ is a semimetal with intriguing ferromagnetism and electronic transport, and intricate interplay between the two. In this forum, Prof. Peng Xiong will present results of their recent measurement of the spin polarization of EuB₆ and a fresh analysis of its nonlinear Hall effect. Their data based on Andreev reflection spectroscopy clearly demonstrate that EuB₆ is not a half metal with a fully spin polarized Fermi surface. Instead, the measured spin polarization values range from 47% to 65%. A two-component model based on a picture of intrinsic electronic/magnetic inhomogeneities and coalescing of a phase with higher conductivity and degree of magnetic ordering was proposed to describe the observed Hall effect. Excellent quantitative agreement and scaling of the Hall resistivity data are obtained.

About Prof. Peng Xiong：Peng Xiong received his B.Sc. in Physics from University of Science and Technology of China in 1987. He received his Ph.D in Physics from Brown University in 1993. He then spent the next four years as a postdoctoral fellow at the University of California at San Diego. He joined the Physics faculty of the Florida State University in November of 1997. He is a member of the Center for Materials Research and Technology (MARTECH). He was a recipient of the Alfred P. Sloan Research Fellowship (1998), University Teaching Award (FSU, 2003), PAI Award for Excellence in Research and Teaching (FSU, 2004), and Developing Scholar Award (FSU, 2007). Recent years he has done much excellent work on magnetic semiconductors, spin injection and detection, nanoscale biosensors, which have been published in Phys. Rev. Lett., Appl. Phys. Lett. and so on. His current interests include mesoscale physics, spintronics, organic/solid-state hybrid structures.