Mirror symmetry breaking in a model insulating cuprate
Mirror symmetry breaking in a model insulating cuprate
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DOI：
10.1038/s41567-021-01210-6
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发表时间：
2020-08
期刊：
影响因子：
19.6
通讯作者：
A. D. L. Torre;K. Seyler;Liuyan Zhao;S. Matteo;M. Scheurer;Y. Li;Biqiong Yu;M. Greven;S. Sachdev;M. Norman;David Hsieh
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文献类型：
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作者：
A. D. L. Torre;K. Seyler;Liuyan Zhao;S. Matteo;M. Scheurer;Y. Li;Biqiong Yu;M. Greven;S. Sachdev;M. Norman;David Hsieh
理解铜超导体复杂的相图是一个突出的挑战。最活跃的研究问题围绕着赝隙和奇怪金属态的性质及其与超导性的关系。相反，人们普遍认为，二维自旋= 1/2反铁磁（AFM）海森堡模型很好地捕捉了莫特绝缘母态的低能物理。然而，最近对几种母铜的大热霍尔电导率的观察似乎违背了这个简单的模型，并表明接近磁手性状态，可以破坏垂直于铜层的所有镜面。本文采用光学二次谐波产生的方法直接求解模型母铜SrCuOCl的点群对称性。我们报道了一个序参量的证据，它打破了所有垂直的镜面，并与零磁场下的磁手性态相一致。虽然它与AFM序参量明显耦合，但我们无法通过通过AFM转变温度（260 K）进行热循环或通过采样不同的空间位置来实现它的时间反转伙伴（）。这表明上述现象可能与赝隙形成机制有关。
Understanding the complex phase diagram of cuprate superconductors is an outstanding challenge. The most actively studied questions surround the nature of the pseudogap and strange metal states and their relationship to superconductivity. In contrast, there is general agreement that the low energy physics of the Mott insulating parent state is well captured by a two-dimensional spin= 1/2 antiferromagnetic (AFM) Heisenberg model. However, recent observations of a large thermal Hall conductivity in several parent cuprates appear to defy this simple model and suggest proximity to a magneto-chiral state that breaks all mirror planes perpendicular to the CuOlayers. Here we use optical second harmonic generation to directly resolve the point group symmetries of the model parent cuprate SrCuOCl. We report evidence of an order parameterthat breaks all perpendicular mirror planes and is consistent with a magneto-chiral state in zero magnetic field. Althoughis clearly coupled to the AFM order parameter, we are unable to realize its time-reversed partner () by thermal cycling through the AFM transition temperature (260 K) or by sampling different spatial locations. This suggests thatonsets aboveand may be relevant to the mechanism of pseudogap formation.