Transport measurements, structure and Mössbauer investigations of FeSe-related novel superconductors under high pressure up to 100GPa

FeSe相关新型超导体在高达100GPa的高压下的输运测量、结构和穆斯堡尔研究

• 批准号: 167738825
• 负责人: Dr. Vadim Ksenofontov
• 金额: --
• 依托单位: Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/167738825?language=en
• 关键词: Transport; measurements; structure; ssbauer; investigations

This project focuses on the investigation of the transport properties of FeSe and related compoundsunder high pressure. FeSe is the simplest of the recently discovered superconductors andcan serve therefore as a model system to gain insight into the mechanism of superconductivityand the structure to property relation of the iron pnictides, iron chalcogenides and related compounds.FeSe is superconducting in the parent phase, no doping is necessary; even more the superconductivity depends strongly on the exact stoichiometry. Different from the arsenides, atetragonal to orthorhombic transition is connected with the superconducting phase. Superconductivitydisappears under pressure, when FeSe transforms reversible into a NiAs-type structure. Nostatic magnetism is observed over the whole pressure vs. temperature phase diagram, measuredby 57Fe-Mössbauer spectroscopy. However, 77Se-NMR spectroscopy gives evidence for shortrange magnetic fluctuations. To solve the question whether magnetism, spin fluctuations, quantumcriticality and/or phonons are important in FeSe we want to investigate structure, magnetism,density of phonon states and resistivity as a function of pressure, magnetic field and temperature.The systems under investigation will be simple model systems such as FeSe, FeSe1-xTex, FeSe1-xSx, CuxFe1-x Se, RuxFe 1-x Se, FeSe–CoAs, TlFe2Se 2-x Asx. The goal is to complete thephase diagram of FeSe and to solve the above addressed questions.

本项目致力于研究FeSe及其化合物在高压下的输运性质。FeSe是最近发现的超导体中最简单的，因此可以作为一个模型系统来深入了解超导体的机制以及铁硫化物和相关化合物的结构与性质的关系。FeSe是母相的超导，不需要掺杂；更重要的是，超导电性强烈地依赖于精确的化学计量比。与砷化物不同的是，非正交晶向正交晶的转变与超导相有关。当FeSe可逆转变为NiAs型结构时，超导性在压力下消失。用57Fe-Mössbauer谱测量，在整个压力-温度相图上观察到了非静磁。然而，77Se-核磁共振波谱提供了短程磁波动的证据。为了解决磁性、自旋涨落、量子临界性和/或声子在FeSe中是否重要的问题，我们想要研究FeSe的结构、磁性、声子态密度和电阻率随压力、磁场和温度的变化。所研究的系统将是简单的模型系统，如FeSe，FeSe1-xTex，FeSe1-xSx，CuxFe1-xSe，RuxFe1-xSe，FeSe-COAS，TlFe2Se 2-xAsx。目的是完成FeSe的相图，解决上述问题。