Quantum many-body interactions in digital oxide superlattices

Abstract

Controlling the electronic properties of interfaces has enormous scientific and technological implications and has been recently extended from semiconductors to complex oxides that host emergent ground states not present in the parent materials. These oxide interfaces present a fundamentally new opportunity where, instead of conventional bandgap engineering, the electronic and magnetic properties can be optimized by engineering quantum many-body interactions. We use an integrated oxide molecular-beam epitaxy and angle-resolved photoemission spectroscopy system to synthesize and investigate the electronic structure of superlattices of the Mott insulator LaMnO(3) and the band insulator SrMnO(3). By digitally varying the separation between interfaces in (LaMnO(3))(2n)/(SrMnO(3))(n) superlattices with atomic-layer precision, we demonstrate that quantum many-body interactions are enhanced, driving the electronic states from a ferromagnetic polaronic metal to a pseudogapped insulating ground state. This work demonstrates how many-body interactions can be engineered at correlated oxide interfaces, an important prerequisite to exploiting such effects in novel electronics.

Visualizing the interfacial evolution from charge compensation to metallic screening across the manganite metal–insulator transition

“…This is evidenced by the observation of conductivity 1 and later superconductivity 4 and magnetism 8 at the interface between two non-magnetic insulators LaAlO 3 and SrTiO 3 as well as novel magnetic phases 2 and correlated electron phases 7 . Manganites, such as La 1 À x Sr x MnO 3 , exhibit many of the exotic bulk phases seen in the complex oxides, with paramagnetic insulating (xr0.2) and ferromagnetic metallic ground states (x40.2) at room temperature and additional charge and orbital ordered phases accessible at low temperatures 9,10 .…”

“…T he interface between transition metal oxides is a playground for stabilizing novel phases not apparent in the parent compounds [1][2][3][4][5][6][7] . This is evidenced by the observation of conductivity 1 and later superconductivity 4 and magnetism 8 at the interface between two non-magnetic insulators LaAlO 3 and SrTiO 3 as well as novel magnetic phases 2 and correlated electron phases 7 .…”

Strong coupling of Jahn-Teller distortion to oxygen-octahedron rotation and functional properties in epitaxially strained orthorhombic LaMnO3

“…Strain and pressure effects on magnetism and metal-insulator transition in LaMnO 3 (Refs. 39-42) and LaMnO 3 -based superlattices [43][44][45][46] have received considerable attention. In particular, previous first-principles studies of LaMnO 3 demonstrate electronic and magnetic phase transitions driven by uniaxial strain.…”

Avoiding polar catastrophe in the growth of polarly orientated nickel perovskite thin films by reactive oxide molecular beam epitaxy

“…15,17,25,26 Compared to these two techniques, the state-of-the-art reactive oxide molecular beam epitaxy (OMBE) is a low-energy deposition method, and can control the growth at atomic scale which can essentially allow the fabrication of high-quality thin films and superlattices with sharp interfaces. [27][28][29][30][31] Moreover, films grown by OMBE have clean and natural "cleaved" surfaces which can further be investigated by in situ combined powerful probes like angle-resolved photoemission spectroscopy (ARPES) 7,32 and scanning tunneling microscopy (STM) that could lay the foundation for future electronic structure studies.…”