报告题目：The Consequences of Structural Disorder for the Magnetic Properties of Transition-Metal Compounds
报告人：牛津大学化学系 Prof. Peter Battle
报告时间：2014年5月14日(周三)上午9:30
报告地点：曹光彪大楼231室
联系人：材料物理所刘小强，13588037856
报告摘要：
A large number of mixed-metal oxides show long-range magnetic ordering at relatively low temperatures. Unfortunately, most of them order antiferromagnetically. They are thus fundamentally interesting but of little practical use. Over the years chemists have made a number of attempts to synthesize compounds that order ferromagnetically, for example by trying to induce two magnetic cations with different electron configurations (perhaps d3 and d5) to occupy similar crystallographic sites in a structure in an ordered manner so as to induce the ferromagnetic coupling predicted by the Goodenough - Kanamori Rules. In most cases, nature refuses to go along with the idea and the cations fill the sites in a disordered manner, resulting in antiferromagnetism or spin-glass-like behaviour. Those compounds that do show a spontaneous magnetization often do so only below a relatively low transition temperature, and often as the result of spin-canting in what is essentially an antiferromagnet, rather than with the complete parallel spin alignment found in a true ferromagnet.This talk will describe our recent attempts to make ferromagnets and the ways in which we have been frustrated by cation disorder. Compounds having the general formulae ABO3 and Ln18Li8M4M’O39 will be used as examples. La3Ni2SbO9, a so-called “relaxor ferromagnet” in which cation disorder is responsible for the observation of a large magnetization will also be described in order to show that some good can come out of everything.
报告人简介：
Peter Battle was an undergraduate student at the University of Bristol before coming to Oxford in 1976 to work as a graduate student with Tony Cheetham. He spent four further years in Oxford as a CEGB Research Fellow before moving to Leeds University as a Lecturer in 1984. He returned to Oxford as a University Lecturer in 1989, and was given the title of Professor of Chemistry in 2002; He is also a tutor at St. Catherine's College. He has held visiting professorships in Caen (1988) and Bordeaux (1995).
