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yexuqing木虫之王 (文学泰斗)
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光驱动YBa2Cu3O6.48的磁场驱逐
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光驱动YBa2Cu3O6.48的磁场驱逐 ▲ 作者：S. Fava, G. De Vecchi, G. Jotzu, M. Buzzi, T. Gebert, Y. Liu, B. Keimer & A. Cavalleri ▲链接： https://www.nature.com/articles/s41586-024-07635-2 ▲摘要： 量子固体中的相干光驱动正在成为一个研究前沿，有许多有趣的非平衡量子相和瞬态光致功能现象的报道，如铁电性、磁性和超导性。在高温铜超导体中，某些声子模式的相干驱动导致了具有类似超导光学性质的瞬态，远远高于它们的转变温度Tc，并且贯穿赝隙相。 然而，关于这种瞬态的微观性质以及如何将其与具有增强载流子迁移率的非超导状态区分开来的问题仍然存在。例如，目前尚不清楚在这种时尚中驱动的铜是否表现出迈斯纳抗磁性。 研究者通过测量放置在样品附近的磁光材料中的法拉第旋转来研究光驱动YBa2Cu3O6.48晶体周围的时间相关磁场。在恒定的外加磁场和相同的驱动条件下，产生类似超导的光学特性，观察到瞬态抗磁响应。 这种响应在尺寸上与具有相似形状和尺寸的平衡型II超导体的响应相当，其体积磁化率χv为?0.3阶。这个值与光诱导的没有超导性的迁移率增加是不相容的。相反，它强调了赝隙相的概念，其中早期的超导相关性被驱动器增强或同步。 ▲ Abstract： Coherent optical driving in quantum solids is emerging as a research frontier, with many reports of interesting non-equilibrium quantum phases and transient photo-induced functional phenomena such as ferroelectricity, magnetism and superconductivity. In high-temperature cuprate superconductors, coherent driving of certain phonon modes has resulted in a transient state with superconducting-like optical properties, observed far above their transition temperature Tc and throughout the pseudogap phase. However, questions remain on the microscopic nature of this transient state and how to distinguish it from a non-superconducting state with enhanced carrier mobility. For example, it is not known whether cuprates driven in this fashion exhibit Meissner diamagnetism. Here we examine the time-dependent magnetic field surrounding an optically driven YBa2Cu3O6.48 crystal by measuring Faraday rotation in a magneto-optic material placed in the vicinity of the sample. For a constant applied magnetic field and under the same driving conditions that result in superconducting-like optical properties, a transient diamagnetic response was observed. This response is comparable in size with that expected in an equilibrium type II superconductor of similar shape and size with a volume susceptibility χv of order ?0.3. This value is incompatible with a photo-induced increase in mobility without superconductivity. Rather, it underscores the notion of a pseudogap phase in which incipient superconducting correlations are enhanced or synchronized by the drive. |
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