非常规超导体的核磁共振研究新进展

Recent progress in NMR studies on unconventional superconductors

核磁共振作为一种重要的谱学研究手段,在非常规超导体的机理研究中发挥了极其重要的作用.近年来随着新型非常规超导材料的发现,对应的核磁共振研究也有了许多新的进展,这些工作对非常规超导电性的机理研究起到了积极的推动作用.本文将就核磁共振技术在奇宇称超导体、铜基高温超导体和笼目结构超导体这三类超导材料中的若干最新研究进展进行一个有针对性的概述和梳理.在奇宇称超导体研究方面,将重点介绍铬基超导家族A_(2)Cr_(3)As_(3)中铁磁量子临界点顺磁侧的超导相图的研究和自旋三重态超导的实验证据,非中心超导体YPtBi中反铁磁自旋涨落及非常规的自旋单态和自旋三重态混合的超导态的发现.在铜氧化物超导体和笼目结构超导体研究方面,将重点介绍YBa_(2)Cu_(3)O_(y)中强磁场诱导的电荷密度波序出现3倍晶胞(λ=3b)公度性的微观实验证据,笼目结构超导体CsV_(3)Sb_5中电荷密度波序和电子关联随压力的演化.希望本文对后续超导电性的机理研究、材料探索及实际应用能起到一些启示作用.

Nuclear magnetic resonance(NMR)is a crucial research tool in spectroscopy,specifically for exploring the mechanisms of unconventional superconductors.The discovery of new unconventional superconducting materials has facilitated several new developments in the field of nuclear magnetic resonance in recent years.These advancements have aided and accelerated the study of unconventional superconductivity mechanisms.This article presents a comprehensive overview of the latest research and its categorization into three types of superconducting materials:odd-parity superconductors,copper-oxide high-temperature superconductors and kagome superconductors.Our study of odd-parity superconductors will focus on the superconducting phase diagram on the paramagnetic side of the ferromagnetic quantum critical point in the chromium-based superconducting family A_(2)Cr_(3)As_(3) and the experimental evidence for spin-triplet superconductivity.Moreover,we will present the results on antiferromagnetic spin fluctuations and the mixed state of spin-singlet and spintriplet pairing in the noncentrosymmetric superconductor YPtBi.For cuprate and kagome-structured superconductors,we will present the microscopic experimental evidence for the commensurateλ=3b periodicity charge density wave modulation induced by strong magnetic fields in YBa_(2)Cu_(3)O_(y).Furthermore,we will also discuss the evolution of charge density wave modulation and electronic correlations with varying pressure in the kagome superconductor CsV_(3)Sb_(5).We hope this study can provide some insights and stimulate further theoretical,material and experimental research in the realm of unconventional superconductors.