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Thursday, May 23

Enhancement of Low-field Magnetoresistance in Manganite: Insulator Composite Films

Margo Staruch, University of Connecticut, Storrs
Materials Science & Technology Division Seminar
11:00 AM — 12:00 PM, Building 4100, Room J-302
Contact: Ho Nyung Lee (hnlee@ornl.gov), 865.574.9782

Abstract

Magnetic field sensors have a wide variety of uses in commercial devices, including medical applications such as medical resonance imaging and in submarine detection for military surveillance. The discovery of low-field magnetoresistance (LFMR), defined as a large change in resistivity with low applied magnetic fields (= 0.5 T), in polycrystalline La1-xSrxMnO3 has attracted attention for its potential in magnetic field sensing applications. LFMR is an extrinsic effect and it can be enhanced through grain boundary engineering, chemical disorder, or inclusion of a secondary insulating phase. In this work, interfacial effects in nanocomposite films of La0.67Sr0.33MnO3 (LSMO) and either ZnO or MgO were studied. LSMO:ZnO composite films were fabricated on (0001) Al2O3 substrate through hydrothermal growth of a ZnO nanorod forest and subsequent spin coating of LSMO. LSMO + Mg(O) films were synthesized on (001) LaAlO3 using a mixed solution route. The effects of the introduction of a secondary phase on the structural, microstructural, magnetic, and electric properties will be presented. The composite films demonstrate significantly enhanced magnetic field sensitivity as compared to pure LSMO and have some of the highest LFMR values reported for similar composites thus far.