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arXiv · 1803.00488

In-situ strain-tuning of the metal-insulator-transition of Ca$_{2}$RuO$_{4}$ in angle-resolved photoemission experiments

S. Riccò·M. Kim·A. Tamai·S. McKeown Walker·F. Y. Bruno·I. Cucchi·E. Cappelli·C. Besnard·T. K. Kim·P. Dudin·M. Hoesch·M. Gutmann·A. Georges·R. S. Perry·F. Baumberger
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Abstract

We report the evolution of the $k$-space electronic structure of lightly doped bulk Ca$_{2}$RuO$_{4}$ with uniaxial strain. Using ultrathin plate-like crystals, we achieve strain levels up to $-4.1\%$, sufficient to suppress the Mott phase and access the previously unexplored metallic state at low temperature. Angle-resolved photoemission experiments performed while tuning the uniaxial strain reveal that metallicity emerges from a marked redistribution of charge within the Ru $t_{2g}$ shell, accompanied by a sudden collapse of the spectral weight in the lower Hubbard band and the emergence of a well defined Fermi surface which is devoid of pseudogaps. Our results highlight the profound roles of lattice energetics and of the multiorbital nature of Ca$_{2}$RuO$_{4}$ in this archetypal Mott transition and open new perspectives for spectroscopic measurements.

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S. Riccò, M. Kim, A. Tamai, S. McKeown Walker, F. Y. Bruno, I. Cucchi, E. Cappelli, C. Besnard, T. K. Kim, P. Dudin, M. Hoesch, M. Gutmann, A. Georges, R. S. Perry, F. Baumberger. 2018-03-01. In-situ strain-tuning of the metal-insulator-transition of Ca$_{2}$RuO$_{4}$ in angle-resolved photoemission experiments. https://doi.org/10.1038/s41467-018-06945-0

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