Regensburg 2016 – wissenschaftliches Programm
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KR: Fachgruppe Kristallographie
KR 4: Crystallography in Materials Science (KR, DF, MI)
KR 4.3: Vortrag
Donnerstag, 10. März 2016, 16:20–16:40, H26
Measuring electron-phonon coupling by RIXS: the showcase of anatase TiO2 — •Simon Moser1, Sara Fatale1, Peter Krüger2, Helmuth Berger1, Philippe Bugnon1, Arnaud Magrez1, Hideharu Niwa3,4, Jun Miyawaki3,4, Yoshihisa Harada3,4, and Marco Grioni1 — 1Ecole Polytechnique Federale de Lausanne, Switzerland — 2University of Chiba, Japan — 3University of Tokyo, Japan — 4SPring-8, Japan
Anatase TiO2 has been proposed for many applications from transparent conducting panels to photovoltaic- and photocatalytic- devices, as well as memristors. However, little is known about the dynamics of the doped-in charge carriers in this textbook insulator. Recently, we have shown by angle resolved photoemission (ARPES) that these populate the bottom of the conduction band and strongly couple to an optical phonon mode, forming so called large polarons (Moser et al., PRL 110, 196403, 2013).
In the present study, we take the point of view of the phonon. By means of bulk-sensitive resonant inelastic X-ray scattering (RIXS) at the Ti L3 edge. We find that the formation of the polaron cloud involves a single 95 meV phonon along the c−axis, besides the 108 meV ab-plane mode previously identified by ARPES. The coupling strength to both modes is the same within error bars, and it is unaffected by the carrier density. This establishes RIXS as a directional and bulk-sensitive probe of electron-phonon coupling in solids (Moser et al. PRL 115, 096404, 2015).