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

在他发现“普通”霍尔效应仅一年后，霍尔发现铁磁性金属中的霍尔电阻获得了一个额外的项，这个项依赖于样品的磁化强度。后一种依赖被称为反常霍尔效应。尽管这种现象早在100多年前就已为人们所熟知，但对于它起源于各种磁性材料的问题，仍然存在争议。反常霍尔效应被广泛地用于研究表面磁性，它在研究纳米尺度磁性以及磁传感器和存储器件应用方面的潜力正在被大力考虑。2006年，一支美国物理团队围绕着他。加州大学伯克利分校的Ivo Souza在对Bloch电子Berry相效应的新见解的启发下，开发了一种新的方法，以Wannier函数形式为基础，以极高的效率和最低的计算成本，从第一原理计算固有的无规霍尔电导率。这个项目的目的是通过结合Ivo Souza教授在AnomalousHall效应方面的专业知识和汉堡大学Stefan Heinze教授在纳米尺度上从头开始描述磁性的各个方面的专业知识，首次从第一原理研究低维磁体中的反常霍尔效应，例如过渡金属薄膜。

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.