Multiferroic Thin Films Nanoscience Symposium 2006 June 15 By: Arramel RuGRuG.
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Transcript of Multiferroic Thin Films Nanoscience Symposium 2006 June 15 By: Arramel RuGRuG.
Multiferroic Thin Multiferroic Thin FilmsFilms
Nanoscience Symposium Nanoscience Symposium 20062006
June 15June 15
By: Arramel
RuG
ContentsContents
1.1. Introduction.Introduction.
2.2. The ME Effects.The ME Effects.
3.3. Fascinating of Multiferroics.Fascinating of Multiferroics.
4.4. Mechanisms of Multiferroicity.Mechanisms of Multiferroicity.
5.5. Multiferroic Thin Films.Multiferroic Thin Films.
6.6. Conclusion.Conclusion.
Hysterisis Hysterisis LoopLoop
Temperature Temperature DependenceDependence
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 EffectsThe Linear ME Effects Induced coupling of Magnetic and Electric properties.Induced coupling of Magnetic and Electric properties. Expansion of free energy of a material.Expansion of free energy of a material.
jiijiSii
Si EEHMEPFHEF 00 2
1),(
More clearly:More clearly:
jjiiij 2i
i E
FP
i
i H
FM
NoteNote::
...2
10 jiijjiij HEHH
ME Signal ME Signal MeasurementsMeasurements
H = 0 H ≠ 0
Fascinating of Fascinating of MultiferroicsMultiferroics
A material that simultaneously exhibits A material that simultaneously exhibits ferromagnetism and ferroelectricity.ferromagnetism and ferroelectricity.
These materials show the largest ME Effects.These materials show the largest ME Effects. Application such as: novel multi-state storage device.Application such as: novel multi-state storage device.
Pacific Custom Cable. Inc Nur. H, et.al, Nature 429, 2004
LimitationsLimitations 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).
PossibilitiesPossibilities
For example:Perovskite BiFeO3
Mechanisms of Mechanisms of MultiferroicityMultiferroicity1. Non-standard Ferroelectrics.1. Non-standard Ferroelectrics.
Lone-pair asymmetry. Lone-pair asymmetry. Electrostatic and size effects.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 inFerroelectricity in TbMnOTbMnO3 3
Kimura T, et.al, Nature 426, 55 (2003).
Existence of the Existence of the CouplingsCouplings
Kimura, et.al, Physical Review B 71, 224425 (2005)Fiebig M, J. Phys. D: Appl. Phys. 38.123 (2005).
(RE)MnO(RE)MnO33 vs Other vs Other MultiferroicsMultiferroics
REMnREMn FE TFE TCC TTNéelNéel
TbMnOTbMnO33 27 K27 K 41 K41 K
GdMnOGdMnO33 23 K23 K 43 K43 K
DyMnODyMnO33 18 K18 K 39 K39 K
OtherOther FE TFE TCC TTNéelNéel
BiFeOBiFeO33 1083 K1083 K 653 K *653 K *
BiMnOBiMnO
33750 K750 K
FM TFM TCC = =
105 K *105 K *
YMnOYMnO33 900 K900 K 70 K **70 K **
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 MagnetsSpiral Magnets
Expression of Spin Density Wave (SDW)Expression of Spin Density Wave (SDW)
Mostovoy. M, Physical Review Letter 96, 067601 (2006).
.Q x P1
P 3213 eMMxd
V e
Phenomenological Approach
332211 x.Qsinx . Qcos M eMeMeM
Thin Films Thin Films
Miniaturization: spintronic, storage, Miniaturization: spintronic, storage, sensor.sensor.
Offers controlled way to synthesize a Offers controlled way to synthesize a Multiferroic materials.Multiferroic materials.
Enhancement of ME couplings is Enhancement of ME couplings is possible.possible.
Growth of Complex oxides with Atomic Layer ControlGrowth of Complex oxides with Atomic Layer Control
Pulsed Laser Deposition & in-situ Pulsed Laser Deposition & in-situ Reflective High Energy Electron Reflective High Energy Electron
DiffractionDiffraction
BiFeOBiFeO33 Thin Film Thin Film
Wang. J, Science, 299, 1719 (2003).
BiMnOBiMnO33 Thin Film Thin Film
Eerenstein , W. Applied Physics Letters, 87, 101906 (2005) Bog G. Kim, et,al. J.of the Korean Physical Society, 46 (2005).
BiCrOBiCrO33 Thin Film Thin Film
Murakami, et.al, Applied Phy Lett 88, 152902 (2006)
ConclusionConclusion AntiferromagneticAntiferromagnetic RMnORMnO33 have shown large ME have shown large ME couplings couplings
at LT.at LT. Thin films exhibit a large spontaneous polarization Thin films exhibit a large spontaneous polarization
compared to bulk.compared to bulk. In thin films the orientation can be controlled. This is a In thin films the orientation can be controlled. This is a
very very important factor in order to increase their spontaneous important factor in order to increase their spontaneous polarization. polarization.
Thin films of Manganites are promising as multiferroic Thin films of Manganites are promising as multiferroic materials withmaterials withM≠0, P=0 at room temperature, which will have enourmous M≠0, P=0 at room temperature, which will have enourmous impact inimpact inmany applications.many applications.
AcknowledgementsAcknowledgements
Thanks to Beatriz NohedaThanks to Beatriz Noheda
FerromagnetismFerromagnetism
Hill, N, J. Phys. Chem. B 2000, 104, 6694-6709
YMnOYMnO3 3 Thin Film Thin Film
The evidence of The evidence of ferroelectric ferroelectric materials.materials.
Two form: Epitaxial Two form: Epitaxial & polycristalline.& polycristalline.
Prellier. W, et.al, J. Phys.: Condens. Matter , 17, R803 (2005)
Utilizes a layered structure of Utilizes a layered structure of thin filmsthin films of magnetic materials.of magnetic materials.
One of the One of the ferromagneticferromagnetic layers is layers is "pinned" so its magnetization direction "pinned" so its magnetization direction remains fixed and the other remains fixed and the other ferromagnetic layer is "free" to rotate ferromagnetic layer is "free" to rotate with the application of a magnetic field.with the application of a magnetic field.
Changes its electrical resistance Changes its electrical resistance depending on the direction of an applied depending on the direction of an applied magnetic field.magnetic field.
Spin ValveSpin Valve
Symmetry ArgumentsSymmetry Arguments
Short ExplanationShort Explanation