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arXiv 2404.06147cond-mat.supr-con
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利用局域噪声磁测量探测二维超导体中的 Berezinskii-Kosterlitz-Thouless 涡旋解绑相变

Probing the Berezinskii-Kosterlitz-Thouless vortex unbinding transition in two-dimensional superconductors using local noise magnetometry

Jonathan B. Curtis, Nikola Maksimovic, Nicholas R. Poniatowski, Amir Yacoby, Bertrand Halperin, Prineha Narang, Eugene Demler

AI总结:

提出用局域噪声磁测量非侵入探测二维超导体 BKT 涡旋解绑相变,并给出噪声的非单调温度依赖和相变处距离无关性等可检验预测。

摘要:

在两个空间维度中,准长程超导性的熔化通过涡旋-反涡旋对的增殖与解绑而发生——这一现象被称为 Berezinskii-Kosterlitz-Thouless(BKT)相变。尽管这种相变的特征已在体测量中被观察到,但这些实验通常复杂、含糊,并且无法解析涡旋解绑相变丰富的物理。在此,我们表明局域噪声磁测量是一种灵敏、非侵入的探测手段,能够提供关于依赖尺度的涡旋动力学的直接信息。特别是,通过解析磁噪声对距离和温度的依赖,或许可以在实验上研究涡旋气体的重整化群流方程,并原位追踪涡旋解绑的起始。具体而言,我们预测:i)噪声对温度具有非单调依赖;ii)在 BKT 相变处,局域噪声几乎与样品-探针距离无关。我们还表明,噪声磁测量能够区分高斯超导序参量涨落与拓扑涡旋涨落,并能检测未束缚涡旋的出现。BKT 相变处微弱的距离依赖也可用于将其与准粒子背景噪声区分开。对于若干非常规超导体,我们的预测可能已处于实验可及范围之内。

英文摘要:

The melting of quasi-long-range superconductivity in two spatial dimensions occurs through the proliferation and unbinding of vortex-antivortex pairs -- a phenomenon known as the Berezinskii-Kosterlitz-Thouless (BKT) transition. Although signatures of this transition have been observed in bulk measurements, these experiments are often complicated, ambiguous, and unable to resolve the rich physics of the vortex unbinding transition. Here we show that local noise magnetometry is a sensitive, noninvasive probe that can provide direct information about the scale-dependent vortex dynamics. In particular, by resolving the distance and temperature dependence of the magnetic noise, it may be possible to experimentally study the renormalization group flow equations of the vortex gas and track the onset of vortex unbinding in situ. Specifically, we predict i) a nonmonotonic dependence of the noise on temperature and ii) the local noise is almost independent of the sample-probe distance at the BKT transition. We also show that noise magnetometry can distinguish Gaussian superconducting order-parameter fluctuations from topological vortex fluctuations and can detect the emergence of unbound vortices. The weak distance dependence at the BKT transition can also be used to distinguish it from quasiparticle background noise. Our predictions may be within experimental reach for a number of unconventional superconductors.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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