In situ strain tuning of the metal-insulator-transition of Ca2RuO4 in angle-resolved photoemission experiments

Riccó, Sara; Kim, M.; Tamai, Anna; Walker, S. McKeown; Bruno, F. Y.; Cucchi, Irène; Cappelli, Edoardo; Besnard, Céline; Kim, T. K.; Dudin, Pavel; Hoesch, Moritz; Gutmann, Matthias J.; Georges, Antoine; Perry, Richard; Baumberger, F.

doi:10.1038/s41467-018-06945-0

Cited by 86 publications

(62 citation statements)

References 46 publications

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“…The results for a wider energy interval, and full computational details can be found in Supplementary Material [22]. We note that these calculations are in good agreement with experimental ARPES data [26,27]. For comparison, we have also plotted DFT+U mean-field band dispersions.…”

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confidence: 73%

Unique Crystal Structure of Ca2RuO4 in the Current Stabilized Semimetallic State

et al. 2019

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The electric-current stabilized semi-metallic state in the quasi-two-dimensional Mott insulator Ca 2 RuO 4 exhibits an exceptionally strong diamagnetism. Through a comprehensive study using neutron and X-ray diffraction, we show that this non-equilibrium phase assumes a crystal structure distinct from those of equilibrium metallic phases realized in the ruthenates by chemical doping, high pressure and epitaxial strain, which in turn leads to a distinct electronic band structure. Dynamical mean field theory calculations based on the crystallographically refined atomic coordinates and realistic Coulomb repulsion parameters indicate a semi-metallic state with partially gapped Fermi surface. Our neutron diffraction data show that the non-equilibrium behavior is homogeneous, with antiferromagnetic long-range order completely suppressed. These results provide a new basis for theoretical work on the origin of the unusual non-equilibrium diamagnetism in Ca 2 RuO 4 .

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confidence: 73%

Unique Crystal Structure of Ca2RuO4 in the Current Stabilized Semimetallic State

et al. 2019

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“…Another important aspect to be discussed is the relevance of the OSMP to the Mott insulating state in Ca2RuO4. Previous theoretical (40,41) and experimental (42)(43)(44) results in CSRO reveal that the Mott transition in Ca2RuO4 (or < 0.2 of CSRO) is triggered by structural transition (L-Pbca to S-Pbca). The Mott state exists only in the S-Pbca phase, because the L-to S-Pbca transition leads to a full occupation of dxy, which in turn gives the essential condition for the formation the Mott state in the other two bands, i.e., half-filled αand β-bands.…”

Section: Discussionmentioning

confidence: 95%

Observation of Kondo hybridization with an orbital-selective Mott phase in 4d Ca2-xSrxRuO4

Kim¹,

Kwon²,

Kim³

et al. 2020

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The heavy fermion state with Kondo-hybridization (KH), usually manifested in f-electron systems with lanthanide or actinide elements, was recently discovered in several 3d transition metal compounds without f-electrons. However, KH has not yet been observed in 4d/5d transition metal compounds, since more extended 4d/5d orbitals do not usually form flat bands that supply localized electrons appropriate for Kondo pairing. Here, we report a doping- and temperature-dependent angle-resolved photoemission study on 4d Ca2-xSrxRuO4, which shows the signature of KH. We observed a spectral weight transfer in the γ-band, reminiscent of an orbital-selective Mott phase (OSMP). The Mott localized γ-band induces the KH with an itinerant β-band, resulting in spectral weight suppression around the Fermi level. Our work is the first to demonstrate the evolution of the OSMP with possible KH among 4d electrons, and thereby expands the material boundary of Kondo physics to 4d multi-orbital systems.

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“…Strain has been shown to induce band structure changes on the order of hundreds of meV in transition metal dichalcogenides [54][55][56][57], although this can requires large strain values that may be difficult to achieve intrinsically in a material without externally applied force. Furthermore, strain has recently been shown capable of driving an insulator-to-metal transition in a correlated electron system [58]. In the case of In/Si(111) it is well known that the displacement of particular atoms can have significant effects on the band structure [31,33,34] which could be partially induced by strain.…”

Section: Excited State Mappingmentioning

confidence: 99%

Excited-state band mapping and momentum-resolved ultrafast population dynamics in In/Si(111) nanowires investigated with XUV-based time- and angle-resolved photoemission spectroscopy

et al. 2019

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We investigate the excited state electronic structure of the model phase transition system In/Si(111) using femtosecond time-and angle-resolved photoemission spectroscopy (trARPES). An extreme ultraviolet (XUV) 500 kHz laser source at 21.7 eV is utilized to map the energy of excited states above the Fermi level, and follow the momentum-resolved population dynamics on a femtosecond time scale. Excited state band mapping is used to characterize the normally unoccupied electronic structure above the Fermi level in both structural phases of indium nanowires on Si (111): the metallic (4x1) and the gapped (8x2) phases. The extracted band positions are compared with the band structure calculated within density functional theory (DFT) within both the LDA and GW approximations. While good overall agreement is found between the GW calculated band structure and experiment, deviations in specific momentum regions may indicate the importance of excitonic effects not accounted for at this level of approximation. To probe the dynamics of these excited states, their momentum-resolved transient population dynamics are extracted with trARPES. The transient intensities are compared to a simulated spectral function modeled by a state population employing a transient elevated electronic temperature as determined experimentally. This allows the momentum-resolved population dynamics to be quantitatively reproduced, revealing important insights into the transfer of energy from the electronic system to the lattice. In particular, a comparison between the magnitude and relaxation time of the transient electronic temperature observed by trARPES with those of the lattice as probed in previous ultrafast electron diffraction studies implies a highly non-thermal phonon distribution at the surface following photo-excitation. This suggests that the energy from the initially excited electronic system is initially transferred to high energy optical phonon modes followed by cooling and thermalization of the photo-excited system by much slower phonon-phonon coupling. arXiv:1812.11385v3 [cond-mat.str-el]

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In situ strain tuning of the metal-insulator-transition of Ca2RuO4 in angle-resolved photoemission experiments

Cited by 86 publications

References 46 publications

Unique Crystal Structure of Ca2RuO4 in the Current Stabilized Semimetallic State

Unique Crystal Structure of Ca2RuO4 in the Current Stabilized Semimetallic State

Observation of Kondo hybridization with an orbital-selective Mott phase in 4d Ca2-xSrxRuO4

Excited-state band mapping and momentum-resolved ultrafast population dynamics in In/Si(111) nanowires investigated with XUV-based time- and angle-resolved photoemission spectroscopy

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