Space-time crystalline order of a high-critical-temperature superconductor with intrinsic Josephson junctions.

Kleiner, Reinhold; Zhou, Xianjing; Dorsch, Eric; Zhang, Xufeng; Koelle, Dieter; Jin, Dafei · Nat Commun · 2021

basic_science · Level V

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Abstract

We theoretically demonstrate that the high-critical-temperature (high-T<sub>c</sub>) superconductor Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8+x</sub> (BSCCO) is a natural candidate for the recently envisioned classical space-time crystal. BSCCO intrinsically forms a stack of Josephson junctions. Under a periodic parametric modulation of the Josephson critical current density, the Josephson currents develop coupled space-time crystalline order, breaking the continuous translational symmetry in both space and time. The modulation frequency and amplitude span a (nonequilibrium) phase diagram for a so-defined spatiotemporal order parameter, which displays rigid pattern formation within a particular region of the phase diagram. Based on our calculations using representative material properties, we propose a laser-modulation experiment to realize the predicted space-time crystalline behavior. Our findings bring new insight into the nature of space-time crystals and, more generally, into nonequilibrium driven condensed matter systems.