Voltage-controlled ferromagnetism and magnetoresistance in LaCoO{sub 3}/SrTiO{sub 3} heterostructures

Journal Article · Thu Nov 14 00:00:00 EST 2013 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4831673· OSTI ID:22217869

Hu, Chengqing; Park, Keun Woo; Yu, Edward T. ^[1]; Posadas, Agham; Demkov, Alexander A. ^[2]; Jordan-Sweet, Jean L. ^[3]

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1. Microelectronics Research Center, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758 (United States)
2. Department of Physics, The University of Texas at Austin, 1 University Station C1600, Austin, Texas 78712 (United States)
3. IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

A LaCoO{sub 3}/SrTiO{sub 3} heterostructure grown on Si (001) is shown to provide electrically switchable ferromagnetism, a large, electrically tunable magnetoresistance, and a vehicle for achieving and probing electrical control over ferromagnetic behavior at submicron dimensions. Fabrication of devices in a field-effect transistor geometry enables application of a gate bias voltage that modulates strain in the heterostructure via the converse piezoelectric effect in SrTiO{sub 3}, leading to an artificial inverse magnetoelectric effect arising from the dependence of ferromagnetism in the LaCoO{sub 3} layer on strain. Below the Curie temperature of the LaCoO{sub 3} layer, this effect leads to modulation of resistance in LaCoO{sub 3} as large as 100%, and magnetoresistance as high as 80%, both of which arise from carrier scattering at ferromagnetic-nonmagnetic interfaces in LaCoO{sub 3}. Finite-element numerical modeling of electric field distributions is used to explain the dependence of carrier transport behavior on gate contact geometry, and a Valet-Fert transport model enables determination of spin polarization in the LaCoO{sub 3} layer. Piezoresponse force microscopy is used to confirm the existence of piezoelectric response in SrTiO{sub 3} grown on Si (001). It is also shown that this structure offers the possibility of achieving exclusive-NOR logic functionality within a single device.

• OSTI ID: 22217869
• Journal Information: Journal of Applied Physics, Vol. 114, Issue 18; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ATOMIC FORCE MICROSCOPY
CARRIERS
CURIE POINT
EQUIPMENT
FABRICATION
FERROMAGNETIC MATERIALS
FERROMAGNETISM
FIELD EFFECT TRANSISTORS
FINITE ELEMENT METHOD
LANTHANUM COMPOUNDS
LEAD
MAGNETIC PROPERTIES
MAGNETORESISTANCE
MOLECULAR BEAM EPITAXY
PIEZOELECTRICITY
SCATTERING
SPIN ORIENTATION
STRAINS
STRONTIUM TITANATES
THIN FILMS