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Trends in (LaMnO3)n/(SrTiO3)m superlattices with varying layer thicknesses.

Jilili J, Cossu F, Schwingenschlögl U - Sci Rep (2015)

Bottom Line: The electronic structure turns out to be highly sensitive to the onsite Coulomb interaction.In contrast to bulk SrTiO3, strongly distorted O octahedra are observed in the SrTiO3 layers with a systematic off centering of the Ti atoms.The systems favour ferromagnetic spin ordering rather than the antiferromagnetic spin ordering of bulk LaMnO3 and all show half-metallicity, while a systematic reduction of the minority spin band gaps as a function of the LaMnO3 and SrTiO3 layer thicknesses originates from modifications of the Ti dxy states.

View Article: PubMed Central - PubMed

Affiliation: KAUST, PSE Division, Thuwal 23955-6900, Kingdom of Saudi Arabia.

ABSTRACT
We investigate the thickness dependence of the structural, electronic, and magnetic properties of (LaMnO3)n/(SrTiO3)m (n, m = 2, 4, 6, 8) superlattices using density functional theory. The electronic structure turns out to be highly sensitive to the onsite Coulomb interaction. In contrast to bulk SrTiO3, strongly distorted O octahedra are observed in the SrTiO3 layers with a systematic off centering of the Ti atoms. The systems favour ferromagnetic spin ordering rather than the antiferromagnetic spin ordering of bulk LaMnO3 and all show half-metallicity, while a systematic reduction of the minority spin band gaps as a function of the LaMnO3 and SrTiO3 layer thicknesses originates from modifications of the Ti dxy states.

No MeSH data available.


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Total densities of states for thicknesses n:m = 2:2, 2:8, and 8:2.
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f3: Total densities of states for thicknesses n:m = 2:2, 2:8, and 8:2.

Mentions: Bulk LaMnO3 is an A-type antiferromagnetic (AFM) Mott insulator, due to a combination of superexchange and Zener double exchange33, whereas SrTiO3 is a non-magnetic insulator (d0 configuration of Ti). Figure 3 shows the total densities of states obtained for the 2:2, 2:8, and 8:2 systems. The general shape of the curves is similar, showing half-metallicity in each case. From −7 to −2 eV we find mainly Mn d, Ti d, and O p states, from −2 to 2 eV Mn d and O p states, and above 2 eV Ti d, La f, Sr d, and O p states. Figure 4 demonstrates systematic changes for varying n and m. The density of states at the Fermi energy remains similar for growing m but increases significantly for growing n due to the fact that these states mainly belong to the LaMnO3 layer. Importantly, for increasing n as well as m, the minority spin band gap is reduced substantially. Indeed, the band onsets in the 2:8 and 8:2 systems are close to the Fermi energy so that the half-metallicity will most likely vanish for n, m > 8.


Trends in (LaMnO3)n/(SrTiO3)m superlattices with varying layer thicknesses.

Jilili J, Cossu F, Schwingenschlögl U - Sci Rep (2015)

Total densities of states for thicknesses n:m = 2:2, 2:8, and 8:2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555181&req=5

f3: Total densities of states for thicknesses n:m = 2:2, 2:8, and 8:2.
Mentions: Bulk LaMnO3 is an A-type antiferromagnetic (AFM) Mott insulator, due to a combination of superexchange and Zener double exchange33, whereas SrTiO3 is a non-magnetic insulator (d0 configuration of Ti). Figure 3 shows the total densities of states obtained for the 2:2, 2:8, and 8:2 systems. The general shape of the curves is similar, showing half-metallicity in each case. From −7 to −2 eV we find mainly Mn d, Ti d, and O p states, from −2 to 2 eV Mn d and O p states, and above 2 eV Ti d, La f, Sr d, and O p states. Figure 4 demonstrates systematic changes for varying n and m. The density of states at the Fermi energy remains similar for growing m but increases significantly for growing n due to the fact that these states mainly belong to the LaMnO3 layer. Importantly, for increasing n as well as m, the minority spin band gap is reduced substantially. Indeed, the band onsets in the 2:8 and 8:2 systems are close to the Fermi energy so that the half-metallicity will most likely vanish for n, m > 8.

Bottom Line: The electronic structure turns out to be highly sensitive to the onsite Coulomb interaction.In contrast to bulk SrTiO3, strongly distorted O octahedra are observed in the SrTiO3 layers with a systematic off centering of the Ti atoms.The systems favour ferromagnetic spin ordering rather than the antiferromagnetic spin ordering of bulk LaMnO3 and all show half-metallicity, while a systematic reduction of the minority spin band gaps as a function of the LaMnO3 and SrTiO3 layer thicknesses originates from modifications of the Ti dxy states.

View Article: PubMed Central - PubMed

Affiliation: KAUST, PSE Division, Thuwal 23955-6900, Kingdom of Saudi Arabia.

ABSTRACT
We investigate the thickness dependence of the structural, electronic, and magnetic properties of (LaMnO3)n/(SrTiO3)m (n, m = 2, 4, 6, 8) superlattices using density functional theory. The electronic structure turns out to be highly sensitive to the onsite Coulomb interaction. In contrast to bulk SrTiO3, strongly distorted O octahedra are observed in the SrTiO3 layers with a systematic off centering of the Ti atoms. The systems favour ferromagnetic spin ordering rather than the antiferromagnetic spin ordering of bulk LaMnO3 and all show half-metallicity, while a systematic reduction of the minority spin band gaps as a function of the LaMnO3 and SrTiO3 layer thicknesses originates from modifications of the Ti dxy states.

No MeSH data available.


Related in: MedlinePlus