Superconductivity in chromium nitrides Pr3Cr10-xN11 with strong electron correlations

• 来源期刊: 国家科学评论（英文版）
• 关键词: Cr-based superconductors nitrides strong electron correlations unconventional superconductivity
• 年，卷（期）: 2020,（1）
• 页码范围: 21-26
• 页数: 6页
• 语种: 英文
• DOI: 10.1093/nsr/nwz129

摘要

Exploration of superconductivity in Cr-based compounds has attracted considerable interest because only a few Cr-based superconductors (CrAs,A2CrsAs3 and ACr3As3 (A =K,Rb,Cs,Na)) have been discovered so far and they show an unconventional pairing mechanism.We report the discovery of bulk superconductivity at 5.25 K in chromium nitride in Pr3Cr10-xN11 with a cubic lattice structure.A relatively large upper critical field of Hc2(0) ～ 12.6 T is determined,which is larger than the estimated Pauli-paramagnetic pair-breaking magnetic field.The material has a large electronic specific-heat coefficient of 170 mJ K-2 mol-1—about 10 times larger than that estimated by the electronic structure calculation,which suggests that correlations between 3d electrons are very strong in Pr3Cr10-xN11,and thus quantum fluctuations might be involved.Electronic structure calculations show that the density of states at the Fermi energy are contributed predominantly by Cr 3d electrons,implying that the superconductivity results mainly from the condensation of Cr 3d electrons.Pr3 Cr10-xN11 represents a rare example of possible unconventional superconductivity emerging in a 3D system with strong electron correlations.Nevertheless,clarification of the specific pairing symmetry needs more investigation.