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Investigating quantum phase transitions using designer-anvil pressure cells

使用设计砧压力盒研究量子相变

基本信息

批准号：
EP/E023746/2
负责人：
Friedrich Grosche
金额：
--
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FE023746%2F2
关键词：
Investigating quantum phase transitions using

项目摘要

Discovery in correlated electron systems research occurs on the boundary of known low temperature states. Next to applied magnetic field, pressure, which affords precise control over the lattice density, is the vehicle of choice for traversing quantum matter phase diagrams and seeking out novel states of matter. This project represents a radical departure in high pressure anvil cell technology: We will structure leads and detection circuits into ceramic anvils by microlithographic methods. The resulting designer anvils provide the reliability, ease of use and versatility necessary for a novel investigation into the high-pressure superconducting state of the archetypal correlated electron superconductor CeCu2Si2. In this intriguing material it appears that two distinct mechanisms can induce superconductivity in different regions of the pressure-temperature phase diagram. Both interactions originate in the Coulomb repulsion between electrons, but one - an effective magnetic interaction - dominates when the material is tuned close to the onset of magnetic order, while the other - an effective charge density interaction - prevails close to a putative transition of the lattice, in which the unit cell volume and hence the lattice density undergoes a weak first order change. In order to investigate the density change quantum phase transition in CeCu2Si2 and in related materials, a detailed study of the pressure dependence of resistivity, heat capacity and thermal expansion will be carried out into the 100 kbar regime. While the investigated pairing mechanism may have ramifications throughout the strongly correlated electron field, including the high-Tc superconductors, the envisaged high pressure technology will be beneficial for a large community of researchers interested in transport or thermodynamic experiments under anvil cell conditions.

相关电子系统研究中的发现发生在已知低温态的边界上。紧挨着外加磁场的是压力，它可以精确控制晶格密度，是穿越量子物质相图和寻找物质新状态的首选载体。这个项目代表了高压砧电池技术的一个根本性的突破：我们将通过微光刻技术将引线和检测电路结构到陶瓷砧中。由此产生的设计砧为原型相关电子超导体CeCu2Si2的高压超导状态的新研究提供了必要的可靠性，易用性和多功能性。在这种有趣的材料中，似乎有两种不同的机制可以在压力-温度相图的不同区域诱导超导性。这两种相互作用都源于电子之间的库仑斥力，但当材料被调整到接近磁阶的起始点时，一种有效的磁相互作用占主导地位，而另一种有效的电荷密度相互作用在接近假定的晶格跃迁时盛行，在这种情况下，单元格体积和晶格密度经历了一个弱的一阶变化。为了研究CeCu2Si2和相关材料的密度变化量子相变，将在100 kbar范围内对电阻率、热容量和热膨胀的压力依赖性进行详细研究。虽然所研究的配对机制可能在整个强相关电子场中产生分支，包括高tc超导体，但设想的高压技术将有利于大量对铁砧电池条件下的输运或热力学实验感兴趣的研究人员。