Road to Room-Temperature Superconductivity: Tc above 260 K in Lanthanum Superhydride under Pressure.
Road to Room-Temperature Superconductivity: Tc above 260 K in Lanthanum Superhydride under Pressure.
复制标题
DOI：
--
复制
发表时间：
2019-06
期刊：
影响因子：
--
通讯作者：
R. Hemley;M. Ahart;Hanyu Liu;M. Somayazulu
中科院分区：
文献类型：
--
作者：
R. Hemley;M. Ahart;Hanyu Liu;M. Somayazulu
使用高压在室温附近实现超导性有着悠久的历史，其中大部分集中在富氢材料中实现这一点。本文简要概述了2018年5月会议上提出的工作，以及动机和技术背景，氢化镧超导性的理论预测以及随后的实验确认。使用密度泛函结构搜索方法结合BCS型模型的理论计算预测了一类新的致密的富氢材料超导体，其超导临界温度在室温附近，压力大于200 GPa。随后实验证实了在镧系中存在一系列这些相，并开发了用于其合成和表征的技术，包括在兆巴压力下测量结构和输运性质。四探针电输运测量确定为LaH10的立方相显示在260 K以上的温度在200 GPa附近的超导性的签名。的结果支持伪四探针电导率测量，临界电流测定，低温X射线衍射，和磁化率测量。测得的高Tc与原始计算结果非常吻合。实验还揭示了Tc在150 K和260 K以上的额外超导相。这一努力突出了高密度富氢材料的新物理学，材料设计在发现和创造新材料方面的成功，以及在室温及以上的新类别超导体Tc的可能性。
The use of high pressure to realize superconductivity in the vicinity of room temperature has a long history, much of it focused on achieving this in hydrogen rich materials. This paper provides a brief overview of the work presented at this May 2018 conference, together with background on motivation and techniques, the theoretical predictions of superconductivity in lanthanum hydride, and the subsequent experimental confirmation. Theoretical calculations using density functional based structure search methods combined with BCS type models predicted a new class of dense, hydrogen rich materials superhydrides with superconducting critical temperatures in the vicinity of room temperature at and above 200 GPa pressures. The existence of a series of these phases in the La H system was subsequently confirmed experimentally, and techniques were developed for their syntheses and characterization, including measurements of structural and transport properties, at megabar pressures. Four probe electrical transport measurements of a cubic phase identified as LaH10 display signatures of superconductivity at temperatures above 260 K near 200 GPa. The results are supported by pseudo four probe conductivity measurements, critical current determinations, low-temperature xray diffraction, and magnetic susceptibility measurements. The measured high Tc is in excellent agreement with the original calculations. The experiments also reveal additional superconducting phases with Tc between 150 K and above 260 K. This effort highlights the novel physics in hydrogen-rich materials at high densities, the success of materials by design in the discovery and creation of new materials, and the possibility of new classes of superconductors Tc at and above room temperature.