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arXiv · 1803.05420

Magnetic-Field Tuning of Light-Induced Superconductivity in Striped La$_{2-x}$Ba$_x$CuO$_4$

D. Nicoletti·D. Fu·O. Mehio·S. Moore·A. S. Disa·G. D. Gu·A. Cavalleri
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Abstract

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 blue-shift, or by the appearance of a Josephson Plasma Resonance in the terahertz-frequency optical properties. Here, we show that this photo-induced state can be strengthened by the application of high external magnetic fields oriented along the c-axis. For a 7-Tesla field, we observe up to a ten-fold enhancement in the transient interlayer phase correlation length, accompanied by a two-fold increase in the relaxation time of the photo-induced 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 photo-induced state may emerge from activated tunneling between optically-excited stripes in adjacent planes.

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D. Nicoletti, D. Fu, O. Mehio, S. Moore, A. S. Disa, G. D. Gu, A. Cavalleri. 2018-12-28. Magnetic-Field Tuning of Light-Induced Superconductivity in Striped La$_{2-x}$Ba$_x$CuO$_4$. https://doi.org/10.1103/physrevlett.121.267003

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