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Quantum Hall Ferromagnets-I Ramin Abolfath Luis Brey Anton Burkov Rene Cote Jim Eisenstein Herb Fertig Steve Girvin Charles Hanna Tomas Jungwirth Kentaro.

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Presentation on theme: "Quantum Hall Ferromagnets-I Ramin Abolfath Luis Brey Anton Burkov Rene Cote Jim Eisenstein Herb Fertig Steve Girvin Charles Hanna Tomas Jungwirth Kentaro."— Presentation transcript:

1 Quantum Hall Ferromagnets-I Ramin Abolfath Luis Brey Anton Burkov Rene Cote Jim Eisenstein Herb Fertig Steve Girvin Charles Hanna Tomas Jungwirth Kentaro Nomura Leo Radzihovksy (Doug) Rajaraman Mark Rasolt Jairo Sinova Kun Yang Les Houches June 2006 University of Texas at Austin

2 A Few Remarks About `Ordinary’ Magnetism

3 Magnetism in Atomic Physics Electrons are Fermions Magnetism due to Fermi Statistics and spin-independent interactions Make all orbitals in an open shell as similar to each other as possible

4 Magnetism in Insulators A playground for strongly-correlated electron physics

5 Magnetism in Metals – Hubbard Picture Simple model – Sophisticated QF Theory Possible Doubles - Interaction Energy Cost U Empties

6 Itinerant Electron Ferromagnetism Bloch-Stoner Picture Singly Occupied Orbitals E  xc E = E 0 + M 2 /D(E F ) - Δ M 2

7 E DOS d s μ μ

8 Itinerant Electron Ferromagnetism Spin-Density Functional Theory One very successful picture of transition metal ferromagnetism is Density Functional Theory. E= E[n,m]= E s [n,m]+E xc [n,m] v = v es + v xc B =  n,m] m/m Hohenberg-Kohn Theorem Kohn-Sham Trick Local Spin-Density Approx.

9 Stoner Criterion - Elements Δ

10 Theory of Itinerant Electron Magnetism by Jurgen Kubler Previous P age Previous P age Next PageNext Page Next P age Next P age Previous P age Previous P age Next PageNext Page Next P age Next P age P ri c e : $ 1 2 5. 0 0 Publishers/Authors: Find out how to include your books in our Search Inside the Book program.Find out how Amazon.com HomeAmazon.com Home | Directory of All StoresDirectory of All Stores Our International Sites: Canada | United Kingdom | Germany | Japan | FranceCanadaUnited KingdomGermanyJapanFrance Contact UsContact Us | Help | Shopping Cart | Your Account | Sell Items | 1-Click SettingsHelpShopping CartYour AccountSell Items1-Click Settings Investor RelationsInvestor Relations | Press Releases | Join Our StaffPress ReleasesJoin Our Staff Conditions of UseConditions of Use | Privacy Notice © 1996-2004, Amazon.com, Inc. or its affiliatesPrivacy Notice Search:Browse: susan's Gold Box List Price: $125.00 Price: $125.00 & This item ships for FREE with Super Saver Shipping. See details. Availability: Special Order see product detailsSee detailssee product details Sign inSign in to turn on 1-Click ordering. Browse sample pages: Front Cover | Table of Contents | Copyright | Index | Back Cover Front CoverTable of ContentsCopyrightIndexBack Cover Search inside this book: Amazon.com Privacy Statement Amazon.com Privacy Statement Amazon.com Shipping Information Amazon.com Shipping Information Amazon.com Returns & Exchanges Amazon.com Returns & Exchanges W h e r e ' s M y S t u f f ? T r a c k y o u r r e c e n t o r d e r s. V i e w o r c h a n g e y o u r o r d e r s i n Y o u r A c c o u n t. r e c e n t o r d e r s Y o u r A c o u n t S h i p p i n g & R e t u r n s S e e o u r s h i p p i n g r a t e s & p o l i c i e s. R e t u r n a n i t e m ( h e r e ' s o u r R e t u r n s P o l i c y ). s h i p i n g r a t e s & p o l i c i e s R e t u r n R e t u r n s P o l i c y N e e d H e l p ? F o r g o t y o u r p a s s w o r d ? C l i c k h e r e. R e d e e m o r b u y a g i f t c e r t i f i c a t e. V i s i t o u r H e l p d e p a r t m e n t. C l i c k h e r e R e d e m b u y V i s i t o u r H e l p d e p a r t m e n t Search for Theory of Itinerant Electron Magnetism JÜRGEN KÜBLER, Institute of Solid State Physics Darmstadt University of Technology Itinerant Electron Ferromagnetism Spin-Density Functional Theory

11 Itinerant Electron Ferromagnetism Quasiparticle and Collective Aspects Q ph spin flip Spin Wave Collective Majority SpinsMinority Spins Fermi Surface Q Singly Occupied Orbitals E

12 Micromagnetics Direction of Magnetization Dipole-Dipole Interactions

13 Micromagnetics

14 A Few Remarks About Spintronics

15 SPIN (Elec)TRONICS = Spin-Torques + Spin-Orbit (AHE+SHE+Spin-Galvanic) + Magnetic Semiconductors

16 Dan Ralph – KITP Spintronics Program Talk www.kitp.ucsb.edu GMR TMR and Spin Torques

17 Hard-disk Technology 10 GByte/(person. year)

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20 A Few Remarks About the Quantum Hall Effect

21 Ga As Si AlGaAs GaAs 100 A AlGaAs Double Quantum Well - Quantum Wells

22 Landau Levels Cyclotron Orbit

23 Integer Quantum Hall Effect  xy /(h/e 2 )  xx

24 Incompressible States & Streda Formula Compressibility Edge Current Conductance and LL degeneracy

25 Integer Quantum Hall Effect  xy /(h/e 2 )  xx

26 QHF- Stoner-Criterion Landau Band Landau-Level Exchange Energy

27 QHF- Stoner-Criterion Maude et al. PRB (2005)

28 Landau Levels - Really! (Ashoori – MIT)

29 Next Time: Skyrmions QHF Anistropy – Ising or XY QHF in Graphene Pseudo-spin Transfer Torques


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