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The 293rd SPring-8 Seminar

Subject/Contents Electron-phonon coupling in high temperature superconducting oxychlorides, a light element model for cuprates
Period from 16:00 to 17:00 Wed., Nov 13 , 2019
Venue Middle-size lecture hall in Public Relations Center
Format Lecture
Abstract

Speaker: Dr. Matteo d’Astuto

Language: English

Affiliation: CNRS (France)

Title: Electron-phonon coupling in high temperature superconducting oxychlorides, a light element model for cuprates

Abstract:
The copper oxychloride cuprate Ca2CuO2Cl2 (CCOC) system, with vacancy or Na doping on the Ca site, is unique among the high temperature superconducting cuprates (HTSCs) since it: lacks high Z atoms; has a simple I4/mmm 1-layer structure, typical of 214 (LSCO) cuprates, but which is stable at all doping and temperatures; and has a strong 2D character due to the replacement of apical oxygen with chlorine [1]. It also shows a remarkable phase diagram, with a superconducting Tc growing to the optimal doping without any minimum around 1/8 doping, despite the observation of charge modulations by by near-field spectro-microscopy [2]. Due to the reduced number of electrons, advanced calculations that incorporate correlation effects, such as quantum Monte Carlo [3], are easier, but relatively little is known about CCOC from an experimental point of view. We are now filling this gap by a comprehensive experimental study covering the whole phase diagram, in particular of the (para)magnon [4] and phonon dispersion [5]. In this talk, we will focus on the phonons modes, particularly of the stretching of the Cu-O bond, as the possible responsible of the very large isotope effect in underdoped cuprate [6]. We will show how this can be linked to anomalies in the dispersion of Cu-O bond stretching mode, and most probably to the kink affecting ARPES bands at the same energy [7], and how RIXS unveil a strong electron-phonon coupling with that mode [8]. We will show how simple DFT fail to describe the mode dispersion [5], and henceforth its coupling with charge carriers. Finally, we will show that the enhancement of the electron-phonon coupling around 1/8 doping is caused by charge order proximity, which is particularly interesting in the oxychlorides, and the needs for a measurement of the bare phonon dispersion in that compound, that will take place in a forthcoming experiment at BL35XU(SPring-8).

[1] Z. Hiroi, N. Kobayashi, M. Takano, Nature vol. 371, 139 (1994); Y. Kohsaka et al. JACS vol.124, 12275 (2002)
[2] T. Hanaguri et al. Nature vol. 430, 1001 (2004); K. Fujita et al. PNAS vol. 111, E3026 (2014)
[3] K. Foyevtsova et al., Phys. Rev. X vol. 4, 031003 (2014); L. K. Wagner, Phys. Rev. B vol. 92, 161116(R) (2015)
[4] B. W. Lebert, et al. Phys. Rev. B vol. 95 155110 (2017); B. Lebert et al., in preparation
[5] M. d'Astuto et al. Phys. Rev. B vol. 88, 014522 (2013); B. Lebert et al., arXiv:1904.08258, hal-02103389 (2019)
[6] M. K. Crawford, et al. Science vol. 250, 1390 (1990)
[7] J. Graf, et al. Phys. Rev. Lett. vol. 100, 227002 (2008)
[8] L. Chaix, et al. Nat Phys. vol. 13, 952 (2017).

Organizer: JASRI Diffraction and Scattering Division Tsutsui Satoshi
e-mail:satoshiatspring8.or.jp/PHS: 3479

Contact Address SPring-8 Seminar secretariat Shinobu Miyoshi / Minako Koujibata General Administration Division/ SPring-8/Japan Synchrotron Radiation Research Institute (JASRI)
+81-(0)791-58-0833
+81-(0)791-58-0830
minako@spring8.or.jp
Last modified 2019-11-11 13:05