Andrea Cavalleri

Abstract:

Nonlinear optical excitation of infrared active lattice vibrations has been shown to melt magnetic or orbital orders and to transform insulators into metals. In cuprates, this technique has been used to remove charge stripes and promote superconductivity, acting in a way opposite to static magnetic fields. Here, we show that excitation of large-amplitude apical oxygen distortions in the cuprate superconductor YBa2 Cu3 O6.5 promotes highly unconventional electronic properties. Below the superconducting transition temperature (Tc = 50 K) inter-bilayer coherence is transiently enhanced at the expense of intra-bilayer coupling. Strikingly, even above T c a qualitatively similar effect is observed up to room temperature, with transient inter-bilayer coherence emerging from the incoherent ground state and similar transfer of spectral weight from high to low frequency. These observations are compatible with previous reports of an inhomogeneous normal state that retains important properties of a superconductor, in which light may be melting competing orders or dynamically synchronizing the interlayer phase. The transient redistribution of coherence discussed here could lead to new strategies to enhance superconductivity in steady state. © 2014 Macmillan Publishers Limited. All rights reserved.

Abstract:

Time- and angle-resolved photoemission spectroscopy directly enables observation of electron dynamics in condensed matter. Using EUV high harmonic probe extends the observation window in energy and momentum. Tuneable mid-infrared pumping allows control of excitation mechanisms. © OSA 2014.

Abstract:

Time- and angle-resolved photoemission spectroscopy directly enables observation of electron dynamics in condensed matter. Using EUV high harmonic probe extends the observation window in energy and momentum. Tuneable mid-infrared pumping allows control of excitation mechanisms.Research in Optical Sciences © OSA 2014.

Abstract:

Nonlinear lattice excitation in YBa2Cu3O6.5 has been shown recently to transiently induce signatures of superconducting coherence up to room temperature. Here, we present ultrafast x-ray diffraction measurements used to determine the corresponding atomic structure. © 2014 OSA.