1. Extraordinary magnetoresistance in GaMnAs ohmic and Coulomb blockade devices Tomas Jungwirth University of Nottingham Bryan Gallagher, Tom Foxon, Richard Campion, Kevin Edmonds, Andrew Rushforth, Chris King et al. Hitachi Cambridge University of Texas and Texas A&M Jorg Wunderlich, Andrew Irvine, Allan MacDonald, Jairo Sinova David Williams, et al. Institute of Physics ASCR Alexander Shick, Karel Výborný, Jan Zemen, Vít Novák, Kamil Olejník, et al. University of Wuerzburg Polish Academy of Sciences Tohoku University Laurens Molenkamp, Charles Gould, et al. Tomasz Dietl, et a. Hideo Ohno, et al.

2. VB-CB VB-IB Jungwirth et al. arXiv:0707.0665, PRB ’07 in press Mn-acceptor level (IB) Short-range ~ M. s potential - additional Mn-hole binding - ferromagnetism - scattering GaAs:Mn extrinsic semiconductor GaAs VB GaMnAs disordered VB  

3. MIT in p-type GaAs: - shallow acc. (30meV) ~ 10 18 cm -3 - Mn (110meV) ~10 20 cm -3 Mobilities: - 3-10x larger in GaAs:C - similar in GaAs:Mg or InAs:Mn > 2% Mn: metallic but strongly disordered Model: SO-coupled, exch.-split Bloch VB & disorder - meaningful but difficult for strong disorder - no better than semi-quantitative   Mn spacing

4. Anisotropic magnetoresistance Rushforth et al. arXiv:cond-mat/0702357, PRL ’07 in press THEORY EXPERIMENT

5. SO & polarized scatterers SO & polarized holes > mag. only Non-crystalline (M vs I) AMR 10-100x weaker contribution to AMR scatering amplitudes max AMR add band-warping  crystalline (M vs [100]) AMR > GaMnAs anisotropic scattering Mn Ga ~

6. Single-electron transistor Two "gates": electric and magnetic Spintronic transistor based on AMR type of effect Huge, gatable, and hysteretic MR Wunderlich et al. PRL ‘06

7. AMR nature of the effect normal AMR Coulomb blockade AMR

8. & electric & magnetic control of Coulomb blockade oscillations Q0Q0 Q0Q0 e 2 /2C  [ 010 ]  M [ 110 ] [ 100 ] [ 110 ] [ 010 ] SO-coupling   (M) Spintronic transistor based on CBAMR SourceDrain Gate VGVG VDVD Q

9. Generic effect in FMs with SO-coupling Combines electrical transistor action with magnetic storage Switching between p-type and n-type transistor by M  programmable logic CBAMR SET

10. CBAMR if change of |  (M)| ~ e 2 /2C CBAMR if change of |  (M)| ~ e 2 /2C  In our (Ga,Mn)As ~ meV (~ 10 Kelvin)In our (Ga,Mn)As ~ meV (~ 10 Kelvin) In room-T ferromagnet change of |  (M)|~100KIn room-T ferromagnet change of |  (M)|~100K Room-T conventional SET (e 2 /2C  >300K) possible Worth trying to look for CBAMR in SO-coupled room-T c metal FMs