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D. A. Mota

Magnetoelastic Coupling and Domain Reconstruction in La 0.7 Sr 0.3 MnO 3 Thin Films Epitaxially Grown on SrTiO 3. D. A. Mota

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D. A. Mota

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  1. Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3 D. A. Mota IFIMUPandIN-Instituteof Nanoscience andNanotechnology, DepartmentofPhysicsandAstronomy, FacultyofScienceofUniversityof Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal New Challenges in the European Area: Young Scientist’s 1st International Baku Forum 20 – 25 MAY 2013, BAKU, AZERBAIJAN

  2. outline • Motivationandaim • LSMOthinfilmsprocessing • Resultsanddiscussion • Summaryand future work • Acknowledgments Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3

  3. Manganites Motivation Why perovskites? Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3

  4. Motivation Mn-Obondlenghts Mn-O-Mnbondangles strain latticemismatch Substrateproperties SrTiO3 stronglydependent Structure Transport Magnetic STOantiferrodistortivephasetransitionat T= 105 K Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3

  5. Motivation – Lsmoresults Segalet al., PRL107, 105501 (2011) • La0.53Sr0.47MnO3; • 11 uc; • STO (100). Result of a coupling between the charge carriers in the film and the soft phonon in the STO, through linked oxygen octahedral motions. The motions of the TiO6 octahedra couple to the MnO6 ones, inducing both static and dynamic changes in their configuration. The static effect appears only below TSTO and do not explain the anomalous temperature behavior of both resistivity and magnetization -> a dynamical coupling was assumed. Thiseffectshouldnotbeobserved in thickerfilmsdue to thepenetrationdepthofthe soft phononsthatwasestimated to bejust 2-3 atomiclayers. Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3

  6. Motivation – lsmoresults Pesquera et al., PRB84, 184412 (2011) • La0.7Sr0.3MnO3; • 26 – 220 nm; • STO (001). Dynamical coupling with soft phonon assumed in an earlier work, was disproved: Since similar temperature behavior of the magnetization is also observed in thicker films. Mechanism proposed -> magnetic domain reconstruction. Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3

  7. Open questionsandAimofthiswork • Verydifferentmechanismshavebeenused to explainthetemperature behavior ofthemagneticandtransportproperties; • No quantitativeanalysiswaspresented in order to understandtheresultsobtained in theLSMOthinfilms; • Weaimatcorrelatingtheorderparameterofthe STO phasetransitionwiththemagneticandtransportpropertieschangesoccuringat 105 K; • LSMOthinfilmsdepositedontoSTO(100) substratesbypulsed laser depositionwiththicknessesbetween 20 and 330 nm. Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3

  8. Resultsanddiscussion D. A. Mota et al. in preparation Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3

  9. Resultsanddiscussion D. A. Mota et al. in preparation Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3

  10. Resultsanddiscussion Figure. HRTEM picture of a cross-sectional sample of 330 nm LSMO thin film deposited on STO substrate D. A. Mota et al. in preparation Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3

  11. Summaryand future work • This work shows how the lattice distortions associated with the STO phase transition induce changes of the physical properties of LSMOthin films ensured by an interface-mediated magnetoeloastic effect; • The increasing rotation angle below the TSTO yields rotations of MnO6 octahedra, which due to the high sensitivity to structural changes of LSMO tune Mn-intersitehopping of charge carriers and localized spin arrangements. • Above the critical thickness, formation of randomly oriented magnetic domain reconstructions, mediated by the order parameter of the STO, takes place in order to relax the increasing tension. • Future work: StudytheeffectofdifferentappliedmagneticfieldsonthemagnetizationaboveTSTO. Magnetoelastic Coupling and Domain Reconstruction in La0.7Sr0.3MnO3 Thin Films Epitaxially Grown on SrTiO3

  12. Thank You!! This work was supported by the Fundação para a Ciência e Tecnologia and COMPETE/QREN/EU, through the project PTDC/CTM/099415/2008

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