Ternary superhydrides under pressure of Anderson's theorem: Near-record superconductivity in (La,Sc)H$_{12}$
Dmitrii V. Semenok, Ivan A. Troyan, Di Zhou, Andrei V. Sadakov, Kirill S. Pervakov, Oleg A. Sobolevskiy, Anna G. Ivanova, Michele Galasso, Frederico Gil Alabars… 展开作者
Dmitrii V. Semenok, Ivan A. Troyan, Di Zhou, Andrei V. Sadakov, Kirill S. Pervakov, Oleg A. Sobolevskiy, Anna G. Ivanova, Michele Galasso, Frederico Gil Alabarse, Wuhao Chen, Chuanying Xi, Toni Helm, Sven Luther, Vladimir M. Pudalov, Viktor V. Struzhkin
备注：
In the new version we have added radio-frequency measurements (Figure 5), as well as a number of additional figures in the Supp. Info
镧-氢系统及其衍生物仍然是实现室温超导最有希望的候选者之一。在本研究中，我们考察了高达220 GPa压力下三元镧-钪超氢化物的形成。LaSc合金与氢反应的主要产物是新发现的立方(La,Sc)H$_{12}$，它在van der Pauw方案的所有六个通道中于244-248 K以下显示出明显的超导转变。在这种具有异常大的晶胞体积的化合物中，在高达68 Tesla的磁场下几乎没有观察到磁阻。合成的(La,Sc)H$_{12}$样品在创纪录的233 K高温下表现出显著的超导二极管和类SQUID效应。此外，我们的分析揭示了较低六方多氢化物(La,Sc)H$_{6-7}$的形成，这可能解释了在274 K附近观察到的电阻异常。265-290 K之间的这种异常也出现在射频传输测量中，并且可能具有超导性质。
英文摘要：
Lanthanum-hydrogen system and its derivatives remain among the most promising for achieving room-temperature superconductivity. In this study, we examined the formation of ternary lanthanum-scandium superhydrides at pressures up to 220 GPa. The primary product of the LaSc alloy's reaction with hydrogen is newly discovered cubic (La,Sc)H$_{12}$, demonstrating clear superconducting transition in all six channels of the van der Pauw scheme below 244-248 K. In this compound with an unusually large unit cell volume, virtually no magnetoresistance was observed in fields up to 68 Tesla. Synthesized samples of (La,Sc)H$_{12}$ demonstrate pronounced superconducting diode and SQUID-like effects at a record high temperature of 233 K. Furthermore, our analysis revealed the formation of lower hexagonal polyhydrides (La,Sc)H$_{6-7}$, which could potentially account for the anomaly in electrical resistance observed near 274 K. This anomaly between 265-290 K also appears in the radio-frequency transmission measurements and may be of a superconducting nature.
Stability and Superconductivity of Ternary Polyhydrides
Center for High Pressure Science & Technology Advanced Research（高压力科学与技术先进研究中心）；Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments (MFree)（极端环境材料前沿研究上海市重点实验室）；Shanghai Advanced Research in Physical Sciences (SHARPS)（上海物理科学先进研究中心）；Quantum Science Center of Guangdong–Hong Kong–Macao Greater Bay Area (Guangdong)（粤港澳大湾区量子科学中心（广东））；Skolkovo Institute of Science and Technology（斯科尔科沃科学技术研究所）；V. L. Ginzburg Center for High-Temperature Superconductivity and Quantum Materials（V.L.金兹堡高温超导与量子材料中心）
Superconductivity in a Scandium Borocarbide with a Layered Crystal Structure
超导体中近室温超导性的发现激发了对传统超导体材料的进一步研究。为了在含轻元素的材料中实现适度高的临界温度$(T_\mathrm{c})$，我们在钪硼碳化物系统中探索了新的超导相。本文报道了一种新的三元Sc-B-C化合物的超导电性。通过Rietveld分析确定的晶体结构属于四面体空间群$P4/ncc$。通过补充使用密度泛函理论计算，发现化合物的化学式表示为Sc $_{20}$ C $_{8-x}$ B $_x$ C $_{20}$（$x=1\:\mathrm{or}\:2$）。有趣的是，少量的B对稳定目前的结构是必不可少的。我们的实验在$T_\mathrm{c}=7.7\:\mathrm{K}$上揭示了典型的II型超导性。此外，我们计算的状态密度内的第一性原理的方法，发现的贡献的Sc-3d轨道是主要负责的超导性。
