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Multiferroic Thin Films

Multiferroic Thin Films. Nanoscience Symposium 2006 June 15. By: Arramel . R u G. Contents. Introduction. The ME Effects. Fascinating of Multiferroics. Mechanisms of Multiferroicity. Multiferroic Thin Films. Conclusion. Hysterisis Loop. Temperature Dependence. H, E.

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Multiferroic Thin Films

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  1. Multiferroic Thin Films Nanoscience Symposium 2006 June 15 By: Arramel RuG

  2. Contents • Introduction. • The ME Effects. • Fascinating of Multiferroics. • Mechanisms of Multiferroicity. • Multiferroic Thin Films. • Conclusion.

  3. Hysterisis Loop Temperature Dependence H, E • Ferromagnetism. • Display spontaneous magnetization. • Produce Hysterisis Loop. • Can be found mainly in metals. • Ferroelectricity. • Display spontaneous polarization. • Produce Hysterisis Loop. • Ferroelectrics are insulators

  4. The Linear ME Effects • Induced coupling of Magnetic and Electric properties. • Expansion of free energy of a material. Note: More clearly:

  5. ME Signal Measurements H = 0 H ≠ 0

  6. Fascinating of Multiferroics • A material that simultaneously exhibits ferromagnetism and ferroelectricity. • These materials show the largest ME Effects. • Application such as: novel multi-state storage device. Nur. H, et.al, Nature 429, 2004 Pacific Custom Cable. Inc

  7. Limitations • Hard to be found in nature & difficult to produce by synthetic routes. • Ferromagnets and Ferroelectrics are excluded each other. Possibilities • “Non standard” Ferromagnets (which is not metallic) or • “Non standard” Ferroelectrics (not driven by d0 cation). For example: Perovskite BiFeO3

  8. Mechanisms of Multiferroicity • 2. Insulating magnets. • ME Effects in inhomogeneous • Antiferromagnetic materials. • Spiral Magnets. 1. Non-standard Ferroelectrics. • Lone-pair asymmetry. • Electrostatic and size effects. Van Aken, et.al, Nature Material, 3, 164 (2004). Kimura, T et.al, Phys. Rev. B68, 060403(R) (2003).

  9. Ferroelectricity inTbMnO3 Kimura T, et.al, Nature 426,55 (2003).

  10. Existence of the Couplings Fiebig M, J. Phys. D: Appl. Phys. 38.123 (2005). Kimura, et.al, Physical Review B 71, 224425 (2005)

  11. (RE)MnO3 vs Other Multiferroics The above oxides only existed on low temperatures. Temperature gap is too wide. * Prellier. W, et.al, J. Phys.: Condens. Matter , 17, R803 (2005) ** Van Aken, et.al, Nature Material, 3, 164 (2004).

  12. Spiral Magnets Expression of Spin Density Wave (SDW) Phenomenological Approach Mostovoy. M, Physical Review Letter96, 067601 (2006).

  13. Thin Films • Miniaturization: spintronic, storage, sensor. • Offers controlled way to synthesize a Multiferroic materials. • Enhancement of ME couplings is possible.

  14. Growth of Complex oxides with Atomic Layer Control Pulsed Laser Deposition & in-situ Reflective High Energy Electron Diffraction

  15. BiFeO3 Thin Film Wang. J, Science, 299, 1719 (2003).

  16. BiMnO3 Thin Film Eerenstein , W. Applied Physics Letters, 87, 101906 (2005) Bog G. Kim, et,al. J.of the Korean Physical Society, 46 (2005).

  17. BiCrO3 Thin Film Murakami, et.al, Applied Phy Lett88, 152902 (2006)

  18. Conclusion • AntiferromagneticRMnO3 have shown large MEcouplings at LT. • Thin films exhibit a large spontaneous polarization compared to bulk. • In thin films the orientation can be controlled. This is a very important factor in order to increase their spontaneous polarization. • Thin films of Manganites are promising as multiferroic materials with M≠0, P=0 at room temperature, which will have enourmous impact in many applications.

  19. Acknowledgements Thanks to Beatriz Noheda

  20. Ferromagnetism Hill, N, J. Phys. Chem. B 2000, 104, 6694-6709

  21. YMnO3 Thin Film • The evidence of ferroelectric materials. • Two form: Epitaxial & polycristalline. Prellier. W, et.al, J. Phys.: Condens. Matter , 17, R803 (2005)

  22. Spin Valve • Utilizes a layered structure of thin films of magnetic materials. • One of the ferromagnetic layers is "pinned" so its magnetization direction remains fixed and the other ferromagnetic layer is "free" to rotate with the application of a magnetic field. • Changes its electrical resistance depending on the direction of an applied magnetic field.

  23. Symmetry Arguments

  24. Short Explanation

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