Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany.
Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
Phys Rev Lett. 2018 Dec 28;121(26):267003. doi: 10.1103/PhysRevLett.121.267003.
Optical excitation of stripe-ordered La_{2-x}Ba_{x}CuO_{4} has been shown to transiently enhance superconducting tunneling between the CuO_{2} planes. This effect was revealed by a blueshift, or by the appearance of a Josephson plasma resonance in the terahertz-frequency optical properties. Here, we show that this photoinduced state can be strengthened by the application of high external magnetic fields oriented along the c axis. For a 7 T field, we observe up to a tenfold enhancement in the transient interlayer phase correlation length, accompanied by a twofold increase in the relaxation time of the photoinduced state. These observations are highly surprising, since static magnetic fields suppress interlayer Josephson tunneling and stabilize stripe order at equilibrium. We interpret our data as an indication that optically enhanced interlayer coupling in La_{2-x}Ba_{x}CuO_{4} does not originate from a simple optical melting of stripes, as previously hypothesized. Rather, we speculate that the photoinduced state may emerge from activated tunneling between optically excited stripes in adjacent planes.
条状有序 La_{2-x}Ba_{x}CuO_{4} 的光学激发已被证明会在 CuO_{2} 平面之间暂时增强超导隧道结效应。这种效应表现为太赫兹频率光学性质中的蓝移或约瑟夫森等离子体共振的出现。在这里，我们表明，通过施加沿 c 轴方向的高外部磁场，可以增强这种光致状态。对于 7 T 的磁场，我们观察到瞬态层间相位相关长度增加了十倍，同时光致状态的弛豫时间增加了一倍。这些观察结果非常令人惊讶，因为静态磁场会抑制层间约瑟夫森隧道结并在平衡时稳定条纹序。我们将我们的数据解释为表明，La_{2-x}Ba_{x}CuO_{4} 中增强的光学层间耦合不是来自以前假设的简单条纹光学熔化。相反，我们推测光致状态可能来自相邻平面中光学激发条纹之间的激活隧道结。
