Ultrafast time-resolved x-ray scattering reveals diffusive charge order dynamics in La2- x Ba x CuO4

Matteo Mitrano; Sangjun Lee; Ali A Husain; Luca Delacretaz; Minhui Zhu; Gilberto de la Peña Munoz; Stella X-L Sun; Young Il Joe; Alexander H Reid; Scott F Wandel; Giacomo Coslovich; William Schlotter; Tim van Driel; John Schneeloch; G D Gu; Sean Hartnoll; Nigel Goldenfeld; Peter Abbamonte

doi:10.1126/sciadv.aax3346

Ultrafast time-resolved x-ray scattering reveals diffusive charge order dynamics in La_{2- x} Ba _x CuO₄

Sci Adv. 2019 Aug 16;5(8):eaax3346. doi: 10.1126/sciadv.aax3346. eCollection 2019 Aug.

Authors

Matteo Mitrano^{1

2}, Sangjun Lee^{1

2}, Ali A Husain^{1

2}, Luca Delacretaz³, Minhui Zhu¹, Gilberto de la Peña Munoz⁴, Stella X-L Sun^{1

2}, Young Il Joe⁵, Alexander H Reid⁴, Scott F Wandel⁴, Giacomo Coslovich⁴, William Schlotter⁴, Tim van Driel⁴, John Schneeloch⁶, G D Gu⁶, Sean Hartnoll³, Nigel Goldenfeld¹, Peter Abbamonte^{1

2}

Affiliations

¹ Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
² Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
³ Department of Physics, Stanford University, Stanford, CA 94305-4060, USA.
⁴ SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
⁵ National Institute of Standards and Technology, Boulder, CO 80305, USA.
⁶ Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.

Abstract

Charge order is universal among high-T _c cuprates, but its relation to superconductivity is unclear. While static order competes with superconductivity, dynamic order may be favorable and even contribute to Cooper pairing. Using time-resolved resonant soft x-ray scattering at a free-electron laser, we show that the charge order in prototypical La_2-x Ba _x CuO₄ exhibits transverse fluctuations at picosecond time scales. These sub-millielectron volt excitations propagate by Brownian-like diffusion and have an energy scale remarkably close to the superconducting T _c. At sub-millielectron volt energy scales, the dynamics are governed by universal scaling laws defined by the propagation of topological defects. Our results show that charge order in La_2-x Ba _x CuO₄ exhibits dynamics favorable to the in-plane superconducting tunneling and establish time-resolved x-rays as a means to study excitations at energy scales inaccessible to conventional scattering techniques.