Probing optically silent superfluid stripes in cuprates
Probing optically silent superfluid stripes in cuprates
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DOI：
10.1126/science.aan3438
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发表时间：
2018-02-02
期刊：
影响因子：
56.9
通讯作者：
Cavalleri, A.
中科院分区：
文献类型：
--
作者：
Rajasekaran, S.;Okamoto, J.;Cavalleri, A.
铜酸盐中的非常规超导性与其他类型的电子秩序共存。然而，其中一些订单由于其对称性而对于大多数实验探针来说是不可见的。例如，超流体条纹的可能存在不容易用线性光学来验证，因为条纹排列会导致层间超导隧道效应平均消失。在这里，我们证明了这种挫败感在非线性光学响应中被消除了。在高于转变温度 T-c = 13 开尔文并高达电荷排序温度 T-co = 55 开尔文的 La1.885Ba0.115CuO4 中观察到巨大的太赫兹三次谐波，这是非线性约瑟夫森隧道效应的特征。我们通过假设存在一对密度波凝聚体来模拟这些结果，其中光学静默隧道模式的非线性混合驱动大的偶极子承载超电流。
Unconventional superconductivity in the cuprates coexists with other types of electronic order. However, some of these orders are invisible to most experimental probes because of their symmetry. For example, the possible existence of superfluid stripes is not easily validated with linear optics, because the stripe alignment causes interlayer superconducting tunneling to vanish on average. Here we show that this frustration is removed in the nonlinear optical response. A giant terahertz third harmonic, characteristic of nonlinear Josephson tunneling, is observed in La1.885Ba0.115CuO4 above the transition temperature T-c = 13 kelvin and up to the charge-ordering temperature T-co = 55 kelvin. We model these results by hypothesizing the presence of a pair density wave condensate, in which nonlinear mixing of optically silent tunneling modes drives large dipole-carrying supercurrents.