Ab initio investigation of the anomalous Hall effect in thin films of transition metals

在他发现“普通”霍尔效应仅仅一年之后，霍尔发现铁磁性金属的霍尔电阻率获得了一个额外的项，这取决于样品的磁化强度。后一种依赖性被称为反常霍尔效应。尽管100多年来这一现象得到了广泛的认识，但关于它在各种磁性材料中的起源仍然存在争议。反常霍尔效应被广泛用于研究表面磁性，它在研究纳米级磁性以及磁传感器和存储器件应用方面的潜力正在被强烈考虑。2006年，一个美国物理团队围绕着教授。加州大学伯克利分校的Ivo Souza受到对布洛赫电子的Berryphase效应的新见解的启发，开发了一种基于万尼尔函数形式主义的新方法，以极高的效率和最小的计算成本从第一性原理计算本征异常霍尔电导率。该项目的目的是通过结合Ivo Souza教授在反常霍尔效应方面的专业知识和汉堡大学Stefan Heinze教授小组在纳米尺度上对磁性各个方面的从头计算描述，首次从第一性原理研究低维磁体（如过渡金属薄膜）中的反常霍尔效应。

Only one year after his discovery of the “ordinary” Hall effect, Hall found that the Hall resistivityin ferromagnetic metals acquires an extra term which depends on the magnetization of the sample.The latter dependence is known as the anomalous Hall effect. Although a well-recognizedphenomenon since more than 100 years, there is still debate about its origins in various magneticmaterials. The Anomalous Hall Effect is intensively used for investigating surface magnetism,and its potential for investigating nanoscale magnetism, as well as for magnetic sensors andmemory devices applications, is being strongly considered. In 2006 a US physics team aroundProf. Ivo Souza at the University of California Berkeley, inspired by the new insight on Berryphase effects on Bloch electrons, has developed a new methodology to calculate the intrinsicAnomalous Hall conductivity from first-principles with extreme efficiency and minimal computationalcosts based on Wannier Functions formalism. The aim of this project is to investigate forthe first time from the first-principles the Anomalous Hall Effect in low-dimensional magnets,such as thin films of transition metals, by combining the expertise of Prof. Ivo Souza in AnomalousHall Effect and the group of Prof. Stefan Heinze in Hamburg University in ab initio descriptionof various aspects of magnetism on the nanoscale.