dielectric

Multiferroic Thin Films : 

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

Contents : 

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

Hysterisis Loop : 

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

The Linear ME Effects : 

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

ME Signal Measurements : 

ME Signal Measurements H = 0 H ? 0

Fascinating of Multiferroics : 

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. Pacific Custom Cable. Inc Nur. H, et.al, Nature 429, 2004

Limitations : 

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

Mechanisms of Multiferroicity : 

Mechanisms of Multiferroicity 1. Non-standard Ferroelectrics. Lone-pair asymmetry. Electrostatic and size effects. 2. Insulating magnets. ME Effects in inhomogeneous Antiferromagnetic materials. Spiral Magnets. Van Aken, et.al, Nature Material, 3, 164 (2004). Kimura, T et.al, Phys. Rev. B 68, 060403(R) (2003).

Ferroelectricity in TbMnO3 : 

Ferroelectricity in TbMnO3 Kimura T, et.al, Nature 426, 55 (2003).

Existence of the Couplings : 

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

(RE)MnO3 vs Other Multiferroics : 

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

Spiral Magnets : 

Spiral Magnets Expression of Spin Density Wave (SDW) Mostovoy. M, Physical Review Letter 96, 067601 (2006). Phenomenological Approach

Thin Films : 

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

Slide 14: 

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

BiFeO3 Thin Film : 

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

BiMnO3 Thin Film : 

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

BiCrO3 Thin Film : 

BiCrO3 Thin Film Murakami, et.al, Applied Phy Lett 88, 152902 (2006)

Conclusion : 

Conclusion Antiferromagnetic RMnO3 have shown large ME couplings 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.

Acknowledgements : 

Acknowledgements Thanks to Beatriz Noheda

Ferromagnetism : 

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

YMnO3 Thin Film : 

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

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. Spin Valve

Symmetry Arguments : 

Symmetry Arguments

Short Explanation : 

Short Explanation