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Title: Electronic Reconstruction at SrMnO3-LaMnO3 Superlattice Interfaces

Abstract

We use resonant soft-x-ray scattering (RSXS) to study the electronic reconstruction at the interface between the Mott insulator LaMnO3 and the band insulator SrMnO3. Superlattices of these two insulators were shown previously to have both ferromagnetism and metallic tendencies. By studying a judiciously chosen superlattice reflection, we show that the interface density of states exhibits a pronounced peak at the Fermi level, similar to that predicted in related titanate superlattices by Okamoto et al. The intensity of this peak correlates with the conductivity and magnetization, suggesting it is the driver of metallic behavior. Our study demonstrates a general strategy for using RSXS to probe the electronic properties of heterostructure interfaces.

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
959528
Report Number(s):
BNL-82514-2009-JA
Journal ID: ISSN 0031-9007; PRLTAO; TRN: US201016%%672
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 99
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; FERMI LEVEL; FERROMAGNETISM; MAGNETIZATION; REFLECTION; SCATTERING; SUPERLATTICES; TITANATES; national synchrotron light source

Citation Formats

Smadici,S., Abbamonte, P., Bhattacharya, A., Zhai, X., Jiang, B., Rusydi, A., Eckstein, J., Bader, S., and Zuo, J. Electronic Reconstruction at SrMnO3-LaMnO3 Superlattice Interfaces. United States: N. p., 2007. Web. doi:10.1103/PhysRevLett.99.196404.
Smadici,S., Abbamonte, P., Bhattacharya, A., Zhai, X., Jiang, B., Rusydi, A., Eckstein, J., Bader, S., & Zuo, J. Electronic Reconstruction at SrMnO3-LaMnO3 Superlattice Interfaces. United States. doi:10.1103/PhysRevLett.99.196404.
Smadici,S., Abbamonte, P., Bhattacharya, A., Zhai, X., Jiang, B., Rusydi, A., Eckstein, J., Bader, S., and Zuo, J. Mon . "Electronic Reconstruction at SrMnO3-LaMnO3 Superlattice Interfaces". United States. doi:10.1103/PhysRevLett.99.196404.
@article{osti_959528,
title = {Electronic Reconstruction at SrMnO3-LaMnO3 Superlattice Interfaces},
author = {Smadici,S. and Abbamonte, P. and Bhattacharya, A. and Zhai, X. and Jiang, B. and Rusydi, A. and Eckstein, J. and Bader, S. and Zuo, J.},
abstractNote = {We use resonant soft-x-ray scattering (RSXS) to study the electronic reconstruction at the interface between the Mott insulator LaMnO3 and the band insulator SrMnO3. Superlattices of these two insulators were shown previously to have both ferromagnetism and metallic tendencies. By studying a judiciously chosen superlattice reflection, we show that the interface density of states exhibits a pronounced peak at the Fermi level, similar to that predicted in related titanate superlattices by Okamoto et al. The intensity of this peak correlates with the conductivity and magnetization, suggesting it is the driver of metallic behavior. Our study demonstrates a general strategy for using RSXS to probe the electronic properties of heterostructure interfaces.},
doi = {10.1103/PhysRevLett.99.196404},
journal = {Physical Review Letters},
number = ,
volume = 99,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • We use resonant soft-x-ray scattering (RSXS) to study the electronic reconstruction at the interface between the Mott insulator LaMnO{sub 3} and the band insulator SrMnO{sub 3}. Superlattices of these two insulators were shown previously to have both ferromagnetism and metallic tendencies [Koida et al., Phys. Rev. B 66, 144418 (2002)]. By studying a judiciously chosen superlattice reflection, we show that the interface density of states exhibits a pronounced peak at the Fermi level, similar to that predicted in related titanate superlattices by Okamoto et al. [Phys. Rev. B 70, 241104(R) (2004)]. The intensity of this peak correlates with the conductivitymore » and magnetization, suggesting it is the driver of metallic behavior. Our study demonstrates a general strategy for using RSXS to probe the electronic properties of heterostructure interfaces.« less
  • The modulation of charge density and spin order in LaMnO32n / SrMnO3n n=1 4 superlattices is studied via Monte Carlo simulations of the double-exchange model. G-type antiferromagnetic barriers in the SrMnO3 regions with low charge density are found to separate ferromagnetic LaMnO3 layers with high charge density. A metal-insulator transition with increasing n is observed in the direction perpendicular to the interfaces. Our simulations provide insight into how disorder-induced localization may cause the metal-insulator transition occurring at n=3 in experiments.
  • We report on the charge transfer at the interface between a band (SrTiO3) and a Mott insulator (LaMnO3) in epitaxial superlattices. We have used combined atomic resolution electron microscopy and spectroscopy, synchrotron X ray reciprocal space maps and magneto transport measurements, to characterize the interface properties. The LaMnO3 layers are always started and terminated in (LaO) planes, giving an overall electron doping to the system. However, the direction of charge leakage is determined by the manganite to titanate thickness ratio in a way controlled by the different epitaxial strain patterns. This result may provide a clue to optimize oxide devicesmore » such as magnetic tunnel junctions and field effect transistors whose operation is determined by the interface properties.« less
  • In systems with strong electron-lattice coupling, such as manganites, orbital degeneracy is lifted, what causes a null expectation value of the orbital moment. Magnetic structure is thus determined by spin-spin superexchange. In titanates, however, with much smaller Jahn-Teller distortions, orbital degeneracy might allow non-zero values of the orbital magnetic moment. Accordingly, novel forms of ferromagnetic superexchange interaction unique to t2g electrons systems have been theoretically predicted, although their experimental observation has remained elusive. Here we report a new kind of Ti3+ ferromagnetism at LaMnO3/SrTiO3 epitaxial interfaces. It results from charge transfer to the empty conduction band of the titanate andmore » has spin and orbital contributions evidencing the role played by orbital degeneracy. The possibility of tuning magnetic alignment (ferromagnetic or antiferromagnetic) of Ti and Mn moments by structural parameters is demonstrated. This result will provide important clues for the understanding of the effects of orbital degeneracy in superexchange coupling.« less