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arXiv · 1812.09844

Orbital-selective confinement effect of Ru $4d$ orbitals in SrRuO$_3$ ultrathin film

Soonmin Kang·Yi Tseng·Beom Hyun Kim·Seokhwan Yun·Byungmin Sohn·Bongju Kim·Daniel McNally·Eugenio Paris·Choong H. Kim·Changyoung Kim·Tae Won Noh·Sumio Ishihara·Thorsten Schmitt·Je-Geun Park
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Abstract

The electronic structure of SrRuO$_3$ thin film with thickness from 50 to 1 unit cell (u.c.) is investigated via the resonant inelastic x-ray scattering (RIXS) technique at the O K-edge to unravel the intriguing interplay of orbital and charge degrees of freedom. We found that orbital-selective quantum confinement effect (QCE) induces the splitting of Ru $4d$ orbitals. At the same time, we observed a clear suppression of the electron-hole continuum across the metal-to-insulator transition (MIT) occurring at the 4 u.c. sample. From these two clear observations we conclude that QCE gives rise to a Mott insulating phase in ultrathin SrRuO$_3$ films. Our interpretation of the RIXS spectra is supported by the configuration interaction calculations of RuO$_6$ clusters.

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Soonmin Kang, Yi Tseng, Beom Hyun Kim, Seokhwan Yun, Byungmin Sohn, Bongju Kim, Daniel McNally, Eugenio Paris, Choong H. Kim, Changyoung Kim, Tae Won Noh, Sumio Ishihara, Thorsten Schmitt, Je-Geun Park. 2018-12-24. Orbital-selective confinement effect of Ru $4d$ orbitals in SrRuO$_3$ ultrathin film. https://doi.org/10.1103/physrevb.99.045113

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