Talk given by

Prof. Matthieu Le Tacon
Institute for Solid State Physics
KIT


Abstract:

Charge order competing with superconductivity has now been observed in essentially all families of high temperature superconducting cuprates. I will review some of the key experimental results obtained in the last couple of years

I will first focus on Cu L-edge resonant scattering experiments that led us to uncover charge density wave (CDW) correlations competing with superconductivity in the YBCO family [1-3], for which a complete temperature and doping dependent phase diagram has been worked out [4]. These investigations have been extended to other families of cuprates (Bi2201[5], Bi2212[6] and Hg1201[7]) demonstrating the ubiquity and the universality of the phenomenon.

Further information was gained from high resolution inelastic x-ray scattering. The observation of a quasi-elastic ‘central peak’ unraveled the static nature of the CDW correlations, attributed to the pining of CDW nanodomains on defects. Low energy phonons exhibit anomalously large superconductivity induced renormalizations close to the CDW ordering wave vector, providing new insights regarding the long-standing debate of the role of the electron-phonon interaction, a major factor influencing the competition between collective instabilities in correlated-electron materials [8].

Finally, I will discuss new results obtained in a heterostructure comprising YBCO and metallic ferromagnet La2/3Ca1/3MnO3, where a stabilization of the CDW phase is concluded and discussed within the scope of tuning the equilibrium conditions of metastable phases via heterostructuring [9].

[1] G. Ghiringhelli et al., Science 337, 821 (2012).

[2] A. J. Achkar et al., Phys. Rev. Lett. 109, 167001 (2012).

[3] S. Blanco-Canosa et al., Phys. Rev. Lett. 110, 187001 (2013).

[4] S. Blanco-Canosa et al., Phys. Rev. B 90, 054513 (2014).

[5] R. Comin et al. et al., Science 343,390 (2014).

[6] E. H.da Silva Neto et al., Science 343,393 (2014).

[7] W. Tabis et al., Nature Communications 5, 5875 (2014).

[8] M. Le Tacon et al., Nature Physics 10, 52 (2014).

[9] A. Frano et al., Nature Materials 15, 831 (2016).