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dc.contributor.authorRoch, Tomás.en_US
dc.date.accessioned2009-05-21T13:54:21Z
dc.date.available2009-05-21T13:54:21Z
dc.date.issued1998-05-21T13:54:21Z
dc.identifier.urihttp://hdl.handle.net/10464/1344
dc.description.abstractThe main purpose of this thesis is to study properties of La2/3Cai/3Mn03, both polycrystalline ceramics and thin films. This material has striking related electrical and magnetic properties. Thin films show colossal negative magnetoresistance (CMR) near transition from an insulating to a metallic state accompanied closely by transition from a paramagnetic to a ferromagnetic state. The double exchange mechanism (DE) and the Jahn-Teller deformations play an important role in CMR effect. Applied pressure has a very similar effect as does an applied magnetic field, except, at low temperatures (T<Tc) the field suppresses the resistivity more than pressure. In our study we performed x-ray diffraction analysis, resistivity and magnetization measurements, as well as measurements of resistivity under applied pressure. The origin of strong resistivity change at low temperatures can be explcdned by the intergranular spin-dependent scattering of DE electrons. Oxygen stoichiometry plays an important role in the magnitude and position of MR(T) maximum. The distortions of structure and Mn-O-Mn bonds in applied pressure axe discussed. The fabrication of La2/3Cai/3Mn03 thin films by pulsed laser deposition was successfully developed. The films grown on (100) SrTiOs substrate are c-axis oriented and exhibit negative magnetoresistance Ap/p(H) of over 400% at 245°C and 4200% at 90 K.en_US
dc.language.isoengen_US
dc.publisherBrock Universityen_US
dc.subjectLanthanum compounds.en_US
dc.subjectManganese.en_US
dc.subjectMagnetoresistance.en_US
dc.subjectThin filmsen_US
dc.titleStudy of colossal magnetoresistance and pressure effects in La2/3Ca1/3MnO2 thin films /en_US
dc.typeElectronic Thesis or Dissertationen
dc.degree.nameM.Sc. Physicsen_US
dc.degree.levelMastersen_US
dc.contributor.departmentDepartment of Physicsen_US
dc.degree.disciplineFaculty of Mathematics and Scienceen_US
refterms.dateFOA2021-08-07T01:57:27Z


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