Optically induced superconductivity in striped La2-xBaxCuO4 by polarization-selective excitation in the near infrared
Optically induced superconductivity in striped La2-xBaxCuO4 by polarization-selective excitation in the near infrared
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DOI：
10.1103/physrevb.90.100503
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发表时间：
2014-09-10
影响因子：
3.7
通讯作者：
Cavalleri, A.
中科院分区：
文献类型：
--
作者：
Nicoletti, D.;Casandruc, E.;Cavalleri, A.
我们发现，超导层间耦合，这是共存的，并抑制了在La 1.885Ba 0.115CuO 4的条纹顺序，可以通过激发与近红外激光脉冲增强。对于低于Tc = 13 K的温度，我们观察到的平衡约瑟夫森等离子体共振，太赫兹频率反射率测量检测到的蓝移。这种测量的关键是能够在低至150 GHz的频率下探测光学特性，检测弱的层间耦合强度。当T > T-c时，在自旋有序温度T-SO接近或等于40 K时，诱导出类似的等离子体共振，但在平衡时不存在。这些效果是令人联想到的，但从质量上不同的光诱导的超导电性所观察到的共振声子激发在La1.675Eu0.2Sr0.125CuO6.5。更重要的是，当近红外泵浦光垂直于超导平面偏振时，低于Tc的层间耦合的增强和高于Tc的层间耦合的出现优先被抑制，这可能是由于与面内激发相比，条带有序的更有效熔化和来自库珀对凝聚体的准粒子的较低有效激发。
We show that superconducting interlayer coupling, which coexists with and is depressed by stripe order in La1.885Ba0.115CuO4, can be enhanced by excitation with near-infrared laser pulses. For temperatures lower than T-c = 13 K, we observe a blue shift of the equilibrium Josephson plasma resonance, detected by terahertz-frequency reflectivity measurements. Key to this measurement is the ability to probe the optical properties at frequencies as low as 150 GHz, detecting the weak interlayer coupling strengths. For T > T-c a similar plasma resonance, absent at equilibrium, is induced up to the spin-ordering temperature T-SO similar or equal to 40 K. These effects are reminiscent but qualitatively different from the light-induced superconductivity observed by resonant phonon excitation in La1.675Eu0.2Sr0.125CuO6.5. Importantly, enhancement of the below-T-c interlayer coupling and its appearance above T-c are preferentially achievedwhen the near-infrared pump light is polarized perpendicular to the superconducting planes, likely due to more effective melting of stripe order and the less effective excitation of quasiparticles from the Cooper pair condensate when compared to in-plane excitation.