Title: Tuning the electronic structure of SrTiO₃/SrFeO_3-x superlattices via composition and vacancy control

Abstract

Using density functional theory-based calculations, we explore the effects of oxygen vacancies and epitaxial layering on the atomic, magnetic, and electronic structure of (SrTiO₃)_n(SrFeO_3-x)₁ superlattices. While structures without oxygen vacancies ($x = 0$) possess small or non-existent band gaps and ferromagnetic ordering in their iron layers, those with large vacancy concentrations ($x = 0.5$) have much larger gaps and antiferromagnetic ordering. Though the computed gaps depend numerically on the delicate energetic balance of vacancy ordering and on the value of Hubbard $$U_{eff}$$ used in the calculations, we demonstrate that changes in layering can tune the band gaps of these superlattices below that of SrTiO₃ (3.2 eV) by raising their valence band maxima. This suggests the possibility that these superlattices could absorb in the solar spectrum, and could serve as water-splitting photocatalysts.

Authors:

Berger, Robert F. ^[1]; Broberg, Daniel P. ^[2]; Neaton, Jeffrey B. ^[3]

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+ Show Author Affiliations

1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Western Washington Univ., Bellingham, WA (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)

Publication Date:

Tue Apr 01 00:00:00 EDT 2014

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Energy Materials Center at Cornell (EMC2)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1383724

Grant/Contract Number:  

SC0001086

Resource Type:

Accepted Manuscript

Journal Name:

APL Materials

Additional Journal Information:

Journal Volume: 2; Journal Issue: 4; Related Information: Emc2 partners with Cornell University (lead); Lawrence Berkeley National Laboratory; Journal ID: ISSN 2166-532X

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; catalysis (homogeneous); catalysis (heterogeneous); energy storage (including batteries and capacitors); hydrogen and fuel cells; defects; charge transport; membrane; materials and chemistry by design; synthesis (novel materials); synthesis (self-assembly); synthesis (scalable processing)