Optically induced superconductivity in stripedLa2−xBaxCuO4by polarization-selective excitation in the near infrared

Abstract

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 Tc = 13 K, we observe a blue-shift of the equilibrium Josephson plasma resonance, detected by terahertzfrequency 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 > Tc a similar plasma resonance, absent at equilibrium, is induced up to the spin-ordering temperature TSO ≃ 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-Tc interlayer coupling and its appearance above Tc are preferentially achieved when the nearinfrared 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.

Reconciliation of local and long-range tilt correlations in underdopedLa2−xBaxCuO4(0≤xBožin1, Zhong2, Knox3 et al. 2015Phys. Rev. B297190View full textAdd to dashboardCite

“…Pumping the x = 0.125 phase in La 1.8−x Eu 0.2 Sr x CuO 4 with 80-meV photons with polarization parallel to the planes induces interlayer superconducting coherence for T < ∼ 15 K [65]; this also causes stripe melting in La 2−x Ba x CuO 4 [66]. In contrast, pumping La 2−x Ba x CuO 4 with polarization perpendicular to the planes enhances interlayer superconducting coherence for x = 0.115, but not for x = 0.125 [67].…”

Enhancement of superconductivity via periodic modulation in a three-dimensional model of cuprates

“…The primary motivation for this investigation came from the recent experiments on transient enhancement of superconductivity in the cuprates via mid-infrared optical excitations [6][7][8]14 . To model these experiments we considered an extension of the t − J − V model of cuprates to three dimensions, and the effects of this threedimensionality on the competition between superconductivity and bond density wave orders.…”

“…Clear evidence of some sort of charge ordering competing with superconductivity has emerged 3,4 . Recently, in a series of exciting papers, it has been demonstrated that optical pumping can significantly enhance the superconductivity in several hole-doped cuprates [5][6][7][8] (for a brief summary see Ref. 9).…”

Photoinduced in-gap excitations in the one-dimensional extended Hubbard model

“…Pumping pulse applied to one-dimensional (1D) Mott insulators with spin-density-wave (SDW) correlation creates not only photoinduced metallic state 1,2 but also a photoinduced charge-density-wave (CDW) state 3 . In two dimensions, the photoexcitation of underdoped cuprates induces a signature of enhanced superconductivity [4][5][6] . Even in a conventional superconductor, an observation of amplitude mode 7 is under intensive investigation within the field of nonequilibrium and nonlinear phenomena induced by transient electric field.…”