Interfacial charge transfer and persistent metallicity of ultrathin SrIrO ₃ /SrRuO ₃ heterostructures

Abstract

Interface quantum materials have yielded a plethora of previously unknown phenomena, including unconventional superconductivity, topological phases, and possible Majorana fermions. Typically, such states are detected at the interface between two insulating constituents by electrical transport, but whether either material is conducting, transport techniques become insensitive to interfacial properties. To overcome these limitations, we use angle-resolved photoemission spectroscopy and molecular beam epitaxy to reveal the electronic structure, charge transfer, doping profile, and carrier effective masses in a layer-by-layer fashion for the interface between the Dirac nodal-line semimetal SrIrO 3 and the correlated metallic Weyl ferromagnet SrRuO 3 . We find that electrons are transferred from the SrIrO 3 to SrRuO 3 , with an estimated screening length of λ = 3.2 ± 0.1 Å. In addition, we find that metallicity is preserved even down to a single SrIrO 3 layer, where the dimensionality-driven metal-insulator transition typically observed in SrIrO 3 is avoided because of strong hybridization of the Ir and Ru t 2 g states.

Heteroepitaxial Control of Fermi Liquid, Hund Metal, and Mott Insulator Phases in Single‐Atomic‐Layer Ruthenates

“…[6][7][8] Most correlated oxides have high carrier densities and therefore their interactions at the heterointerfaces are significantly short. Previous studies have shown that, in the correlated oxide interfaces, charge modulations, [9][10][11] as well as magnetic, [12] orbital, [13] and structural [14] reconstructions occur within several atomic layers from the interface. There have been a few systematic studies of highelectron-mobility oxide heterostructures whose carrier densities are comparable to that of conventional semiconductors.…”

Emergent topological states via digital (001) oxide superlattices

“…While the (001) surface is the most natural surface for a (001)-grown oxide superlattice, a (100) or (010) surface can also be obtained by either cleaving the sample or mechanically polishing the sample 91,92 . Such preparation of (100) or (010) surfaces is routinely made in transmission electron microscopy (TEM) and cross-sectional scanning tunneling microscopy (STM) measurements [93][94][95][96] . Finally, we comment on how one may separate the topological surface bands from the bulk spectrum.…”

Electric Control of 2D Van Hove Singularity in Oxide Ultra‐Thin Films

“…1a) [14]. Finally, the external electric field should be strongly screened by charge carriers in a metallic system for a controllable region to be confined near the surface [20][21][22][23]. Due to these various challenges, only a few controllable and practical devices have been realized and reported.…”

“…To overcome the above issues and fully exploit the functionality of VHSs, we utilize an atomically ultra-thin SrRuO 3 (SRO) film with a 2D VHS located near E F [24,25]. Ultrathin and superlattice film systems have been extensively stud-ied due to their strong tunability [23,[25][26][27][28][29]. In this study, we experimentally control a VHS with Lifshitz transition (Fig.…”