Interface properties of magnetic tunnel junction La0.7Sr0.3MnO3/SrTiO3 superlattices studied by standing-wave excited photoemission spectroscopy

被引：60

作者：

Gray, A. X. ^{[1
,2
]}

Papp, C. ^{[2
,3
]}

Balke, B. ^{[2
,4
]}

Yang, S. -H. ^{[5
]}

Huijben, M. ^{[6
]}

Rotenberg, E. ^{[7
]}

Bostwick, A. ^{[7
]}

Ueda, S. ^{[8
]}

Yamashita, Y. ^{[8
]}

Kobayashi, K. ^{[8
]}

Gullikson, E. M. ^{[7
]}

Kortright, J. B. ^{[2
]}

de Groot, F. M. F. ^{[9
]}

Rijnders, G. ^{[6
]}

Blank, D. H. A. ^{[6
]}

Ramesh, R. ^{[2
,10
,11
]}

Fadley, C. S. ^{[1
,2
]}

机构：

[1] Univ Calif Davis, Dept Phys, Davis, CA 95616 USA

[2] Univ Calif Berkeley, Lawrence Berkeley Lab, Div Mat Sci, Berkeley, CA 94720 USA

[3] Univ Erlangen Nurnberg, Lehrstuhl Phys Chem 2, D-91058 Erlangen, Germany

[4] Johannes Gutenberg Univ Mainz, Inst Anorgan & Analyt Chem, D-55099 Mainz, Germany

[5] IBM Almaden Res Ctr, San Jose, CA 95120 USA

[6] Univ Twente, Fac Sci & Technol, MESA Inst Nanotechnol, NL-7500 AE Enschede, Netherlands

[7] Univ Calif Berkeley, Lawrence Berkeley Lab, Adv Light Source, Berkeley, CA 94720 USA

[8] Natl Inst Mat Sci, NIMS Beamline Stn SPring 8, Mikazuki, Hyogo 6795148, Japan

[9] Univ Utrecht, Dept Chem, NL-3584 CA Utrecht, Netherlands

[10] Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA

[11] Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA

来源：

PHYSICAL REVIEW B | 2010年 / 82卷 / 20期

关键词：

ROOM-TEMPERATURE; MAGNETORESISTANCE; OXIDES;

D O I：

10.1103/PhysRevB.82.205116

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

The chemical and electronic-structure profiles of magnetic tunnel junction (MTJ) La0.7Sr0.3MnO3/SrTiO3 (LSMO/STO) superlattices have been quantitatively determined via soft and hard x-ray standing-wave excited photoemission, x-ray absorption and x-ray reflectivity, in conjunction with x-ray optical and core-hole multiplet theoretical modeling. Epitaxial superlattice samples consisting of 48 and 120 bilayers of LSMO and STO, each nominally four unit cells thick, and still exhibiting LSMO ferromagnetism, were studied. By varying the incidence angle around the superlattice Bragg condition, the standing wave was moved vertically through the interfaces. By comparing experiment to x-ray optical calculations, the detailed chemical profile of the superlattice and its interfaces was quantitatively derived with angstrom precision. The multilayers were found to have a small similar to 6% change in periodicity from top to bottom. Interface compositional mixing or roughness over similar to 6 angstrom was also found, as well as a significant change in the soft x-ray optical coefficients of LSMO near the interface. The soft x-ray photoemission data exhibit a shift in the position of the Mn 3p peak near the interface, which is not observed for Mn 3s. Combined with core-hole multiplet theory incorporating Jahn-Teller distortion, these results indicate a change in the Mn bonding state near the LSMO/STO interface. Our results thus further clarify the reduced (MTJ) performance of LSMO/STO compared to ideal theoretical expectations.

引用

页数：9

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