Surveying Hebel-Slichter peaks in conventional-ish superconductors

The presence of a Hebel-Slichter peak in NMR or µSR measurements just below the critical temperature of superconductors is taken to be strong evidence for conventional behaviour and its absence heralds unconventional physics. Making this measurement has been a mainstay of NMR studies of superconductors for more than 50 years, but even though muon measurements famously revealed this phenomenon in fulleride superconductors well before NMR was able to reproduce the finding, it has rarely been used otherwise. Here we propose to make a broad survey across superconductors known from NMR to display Hebel-Slichter peaks to see how best to measure the phenomenon with muons. This is likely to be exceedingly challenging technically but success could open up a new field of study for µSR.在超导体临界温度以下开展的核磁共振（NMR）或缪子自旋共振（µSR）测量中，若观测到Hebel-Slichter峰（Hebel-Slichter peak），则被视作该超导体呈现常规超导行为的有力证据；反之，若无该峰，则预示着存在非传统超导物理现象。五十余年来，此类测量一直是超导体核磁共振研究的核心手段之一。尽管缪子测量早在核磁共振能够复现该发现之前，就已在富勒烯超导体中成功观测到这一现象，但该方法在此之外的应用却极为有限。本文拟针对已通过核磁共振观测到Hebel-Slichter峰的超导体开展系统性普查，以期探索利用缪子最优测量该现象的方案。该工作在技术层面极富挑战性，但一旦取得成功，将为缪子自旋共振（µSR）研究开辟全新的研究领域。