Two peer-approved experiments at SPring-8: the Fermi surface of Co-doped BaFe2As2 and the electron spin-density in the NbFe2 system

Lead Research Organisation: University of Bristol
Department Name: Physics

Abstract

Superconductivity and magnetism are two fascinating phenomena which can occur in materials. Our understanding of the mechanisms responsible is based on a quantum mechanical description of how the electrons in the material are behaving. It is possible to study these electrons by scattering of x-rays off them, much in the same way as snooker balls are scattered by each other. However, we need a very intense source of x-rays, known as a synchrotron.We have been awarded experimental time at a synchrotron in Japan for two separate studies of the electronic properties of two different materials. In the first study on a superconductor, we will investigate a particular aspect of the electronic behaviour, looking for a characteristic surface known as the Fermi surface, which may be crucial to explaining why these particular materials superconduct in the manner in which they do. In the second study, we propose to look at the nature of the magnetism in a compound whose behaviour has been found to be rather unusual. It is hoped that by studying how the magnetism is distributed, it might tell us something about gaps in our understanding.

Publications

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Haynes T (2012) Ferrimagnetism in Fe-rich NbFe 2 in Physical Review B

 
Description Superconductivity refers to the complete vanishing of electrical resistivity below some critical temperature (which is typically a couple of hundred degrees below room temperature). Perhaps the ultimate goal of this field of research would be to discover a superconductor which operates at room temperature. The so-called "iron pnictide" superconductors were discovered in 2008 and were immediately compared and contrasted with another group of materials called the cuprates. In this part of the project, we made a bulk measurement of the something called the Fermi surface of one of these materials, Co-doped BaFe2As2, which describes how the electrons behave.

In the second part of this project we looked at magnetism in the NbFe2 system. By changing the precise amounts of Nb and Fe in this compound, a variety of behaviours can be elicited. By scattering polarised light from the electrons in this material, we were able to establish the nature of the magnetic order for one particular composition.
Exploitation Route The research produced was of a fundamental nature. Both superconductivity and magnetism have substantial practical applications. A better understanding of the fundamental mechanisms responsible for these phenomena will potentially lead to new materials and technologies.
Sectors Digital/Communication/Information Technologies (including Software),Electronics,Energy

 
Description There was large training element to this research, which resulted in the up-skilling of Ph.D. students and a post-doc. There was also cultural experience and exchange through working at a synchrotron source in Japan.
First Year Of Impact 2009
Sector Electronics
Impact Types Policy & public services