抵御大变形超导体的发现

Discovery of robust superconductivity against volume shrinkage

超导体在压力的作用下会产生原子间距的缩小,进而导致晶格参数的改变,甚至能使其原子排列规律变化,引发结构相变.超导体的超导电性是一种演生现象,是由超导体中所包含的电荷、自旋、轨道、晶格等多种相互作用的自由度所决定的.因此,当超导体在外部压力作用下发生晶体结构的变化,通常都会引起超导电性的改变,尤其超导转变温度的变化.本文介绍近年发现的一类能够抵御大变形的超导体(robust super-conductivity against volume shrinkage,RSAVS)——这类超导体在压力作用下,即使发生很大的体积压缩,其超导转变温度仍保持不变.这种奇异的能抵御压缩变形的稳定超导电性最初是在对高熵合金的高压研究中观察到的,后续研究发现在广泛应用的商业化NbTi合金以及Nb,Ta等金属元素超导体中也具有这种可抵御大变形的超导电性.分析结果显示,这类超导体都具有体心立方晶体结构,并由过渡族金属元素构成.这种超导体的发现为统一理解“什么因素决定了超导体的超导转变温度?”这一关键问题提出了新的研究课题和挑战.

The superconducting transition temperature(Tc)of superconductor is related intimately to multiple degree of freedom of charge,spin,orbital and lattice.Many studies have indicated that pressure is an effective way to tune Tc though changing crystal structure and electronic structure.Here,we report a new progress made in the high-pressure studies-discovery of a new type of superconductors whose T_(c) is robust against large volume shrinkage under extremely high pressure,named RSAVS(robust superconductivity against volume shrinkage)superconductor.Such RSAVS behavior was observed initially in the high entropy alloys of(TaNb)_(0.67)(HfZrTi)_(0.33) and(ScZrNbTa)_(0.6)(RhPd)_(0.4),then in the widely-used NbTi alloy,Nb and Ta elements.Analysis shows that this type of superconductor possesses a body-centered cubic crystal structure and is composed of transition metal elements.The observed results not only present new research topics but also raise the question of what determines T_(c) of conventional or unconventional superconductors.