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Laura CHAIX, equipe MRS, présentera
le séminaire mensuel NÉEL

Mardi 15 Novembre 2022 à 9h30

Salle des séminaires Bât. A



Titre : Resonant Inelastic X-ray Scattering study of CDW and excitations in cuprate superconductors

Résumé :

The mechanism of high-TC superconductivity in cuprates remains an unsolved question since its discovery in 1986, a compelling picture of the Cooper pairing mechanism being still missing. In these strongly interacting electron systems, disentangling each electronic instability or competing/intertwined phase, coexisting with or close to superconductivity, is at the heart of the problem. Among them, the Charge Density Waves (CDW), which have been predicted since decades [1] and are now reported in nearly all cuprate superconductors, are still at the core of intense investigation, their microscopic origin and relation with the superconductivity remaining open questions. Since the early experimental studies on La-based cuprates toward the more recent works on Hg-based cuprates, the CDW has been extensively studied using different experimental probes [2]. Recently, the Resonant Inelastic X-ray Scattering (RIXS) technique has emerged as decisive to study the CDW and its corresponding fluctuations/excitations [3]. 

After a short introduction on the current research on the CDW in high-TC cuprates, I will briefly introduce the RIXS technique. I will then illustrate how the RIXS can probe the CDW by presenting one example:  the copper oxychloride compound. Indeed, in this system a surface CDW was detected more than fifteen years ago [4], with no evidence regarding its bulk behavior. Using RIXS, we successfully revealed a bulk CDW in this material. Combining RIXS with non-resonant IXS, we also focused on the lattice excitations, and evidenced electron-phonon coupling anomalies occurring in the presence of dispersive CDW excitations [5].

[1] J. Zaanen and O. Gunnarsson, Phys. Rev. B 40, 7391(R) (1989) and K. Machida, Physica C: Superconductivity 158, 192 (1989).

[2] J. M. Tranquada et al., Nature 375, 561 (1995) ; J. E. Hoffman et al., Science 295, 466 (2002) ; T. Wu, et al., Nature (London) 477, 191 (2011) ; R. Comin and A. Damascelli, Annu. Rev. Condens. Matter Phys. 7, 369 (2016) and A. Frano et al., J. Phys.: Condens. Matter 32, 374005 (2020).

[3] H. Miao et al., Phys. Rev. X 9, 031042 (2019) ; R. Arpaia et al., Science 365, 906 (2019) ; B. Yu et al., Phys. Rev. X 10, 021059 (2020) ; J. Li et al., Proc. Natl. Acad. Sci. 117, 16219 (2020) and W. S. Lee et al., Nat. Phys. 17, 53 (2021).

[4] T. Hanaguri et al., Nature 430, 1001 (2004).

[5] L. Chaix et al., Phys. Rev. Research 4, 033004 (2022).