Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Phys Rev Lett. 2013 May 24;110(21):217002. doi: 10.1103/PhysRevLett.110.217002. Epub 2013 May 22.
We use pump-probe spectroscopy to measure the photoinduced reflectivity ΔR of the electron-doped cuprate superconductor Nd(2-x)Ce(x)CuO(4+δ) at a value of x near optimal doping, as a function of time, temperature, and laser fluence. We observe the onset of a negative ΔR signal at T(*)≈75 K, above the superconducting transition temperature, T(c), of 23 K. The relatively slow decay of ΔR, compared to the analogous signal in hole doped compounds, allows us to resolve time-temperature scaling consistent with critical fluctuations. A positive ΔR signal onsets at T(c) that we associate with superconducting order. We find that the two signals are strongly coupled below T(c), in a manner that suggests a repulsive interaction between superconductivity and another fluctuating order.
我们使用泵浦探测光谱法测量电子掺杂 cuprate 超导体 Nd(2-x)Ce(x)CuO(4+δ)在接近最佳掺杂浓度 x 处的光致反射率 ΔR，作为时间、温度和激光强度的函数。我们观察到在 T(*)≈75 K 处出现负 ΔR 信号，高于超导转变温度 T(c)为 23 K。与空穴掺杂化合物中的类似信号相比，ΔR 的相对缓慢衰减使我们能够解析符合临界涨落的时-温标度。在 T(c)处出现正 ΔR 信号，我们将其与超导有序相关联。我们发现这两个信号在 T(c)以下强烈耦合，这表明超导性和另一种涨落有序之间存在排斥相互作用。
