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Multiferroic Thin Films

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Multiferroic Thin Films By: Arramel Nanoscience Symposium 2006 June 15 RuG Contents Introduction. The ME Effects. Fascinating of Multiferroics. Mechanisms of ... – PowerPoint PPT presentation

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Title: Multiferroic Thin Films


1
Multiferroic Thin Films
By Arramel
  • Nanoscience Symposium 2006
  • June 15

RuG
2
Contents
  1. Introduction.
  2. The ME Effects.
  3. Fascinating of Multiferroics.
  4. Mechanisms of Multiferroicity.
  5. Multiferroic Thin Films.
  6. 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.


Pacific Custom Cable. Inc
Nur. H, et.al, Nature 429, 2004
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
  • 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).
9
Ferroelectricity in TbMnO3
Kimura T, et.al, Nature 426, 55 (2003).
10
Existence of the Couplings
Kimura, et.al, Physical Review B 71, 224425 (2005)
Fiebig M, J. Phys. D Appl. Phys. 38.123 (2005).
11
(RE)MnO3 vs Other Multiferroics
REMn FE TC TNéel
TbMnO3 27 K 41 K
GdMnO3 23 K 43 K
DyMnO3 18 K 39 K
Other FE TC TNéel
BiFeO3 1083 K 653 K
BiMnO3 750 K FM TC 105 K
YMnO3 900 K 70 K
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 Letter 96, 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 Lett 88, 152902
(2006)
18
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, P0 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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