Electronic phase separation at LaAlO3/SrTiO3 interfaces tunable by oxygen deficiency

被引：24

作者：

Strocov, V. N. ^{[1
]}

Chikina, A. ^{[1
]}

Caputo, M. ^{[1
]}

Husanu, M-A ^{[1
,2
]}

Bisti, F. ^{[1
]}

Bracher, D. ^{[1
]}

Schmitt, T. ^{[1
]}

Granozio, F. Miletto ^{[3
]}

Vaz, C. A. F. ^{[1
]}

Lechermann, F. ^{[4
]}

机构：

[1] Paul Scherrer Inst, Swiss Light Source, CH-5232 Villigen, Switzerland

[2] Natl Inst Mat Phys, Atomistilor 405A, RO-077125 Magurele, Romania

[3] Complesso Univ Monte S Angelo, CNR, SPIN, Via Cintia, I-180126 Naples, Italy

[4] Univ Hamburg, Inst Theoret Phys, Jungiusstr 9, DE-20355 Hamburg, Germany

来源：

PHYSICAL REVIEW MATERIALS | 2019年 / 3卷 / 10期

基金：

瑞士国家科学基金会;

关键词：

OXIDE; SUPERCONDUCTIVITY; COEXISTENCE; SCATTERING; BEAMLINE; ADRESS; SRTIO3;

D O I：

10.1103/PhysRevMaterials.3.106001

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Electronic phase separation is crucial for the fascinating macroscopic properties of the LaAlO3/SrTiO3 (LAO/STO) paradigm oxide interface, including the coexistence of superconductivity and ferromagnetism. We investigate this phenomenon using angle-resolved photoelectron spectroscopy (ARPES) in the soft-x-ray energy range, where the enhanced probing depth combined with resonant photoexcitation allow us access to fundamental electronic structure characteristics - momentum-resolved spectral function, dispersions and ordering of energy bands, Fermi surface - of buried interfaces. Our experiment uses x-ray irradiation of the LAO/STO interface to tune its oxygen deficiency, building up a dichotomic system where mobile weakly correlated Ti t(2g) electrons coexist with localized strongly correlated Ti e(g) ones. The ARPES spectra dynamics under x-ray irradiation shows a gradual intensity increase under constant Luttinger count of the Fermi surface. This fact identifies electronic phase separation (EPS) where the mobile electrons accumulate in conducting puddles with fixed electronic structure embedded in an insulating host phase, and allows us to estimate the lateral fraction of these puddles. We discuss the physics of EPS invoking a theoretical picture of oxygen-vacancy clustering, promoted by the magnetism of the localized Ti e(g) electrons, and repelling of the mobile t(2g) electrons from these clusters. Our results on the irradiation-tuned EPS elucidate the intrinsic one taking place at the stoichiometric LAO/STO interfaces.

引用

页数：9

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