View
219
Download
2
Embed Size (px)
Citation preview
Single electron Transport in diluted magnetic semiconductor quantum dots
Department of Applied Physics, U. Alicante SPAINMaterial Science Institute of Madrid, CSIC SPAIN
J. Fernández-Rossier, R. Aguado
www.ua.es/personal/jfrossier/
Spin dependentCapacitance
Z19-1
Gate Tuning Anisotropy
CdTe+1 Mn
GaMnAs Single electron transistor
cond-mat/0602608 Coulomb blockade anisotropic magnetoresistance: Single electronics meets spintronicsAuthors:J. Wunderlich et al.
Mn(2+)
S=5/22S+1=6
PL
Int
ensi
ty
www.ua.es/personal/jfrossier/
Y. Léger et al., PRL 95, 047403 (05)L. Besombes et al. PRL 93, 207403 (04)
Single ExcitonSpectroscopy
1 Mn per dot
MSJMSJHH eezzheh
0
ST=Se+M
Heisenberg
Ising
25zM
21zM
23zM
Mzhe JJ
Single exciton spectroscopy (1 Mn dot)
EXPERIMENTS:Y. Léger et al. PRL 95, 047403 (05)
THEORY: J. Fernández-Rossier, PRB73, 045301 (06)
WE UNDERSTAND e+h+Mn
NENH Ndot
Theory I: The dot STATES
MSffJffVH vvvvvv
vvv
nnGvdot
','
',',
NUMERICAL DIAGONALIZATION
STATES WITH a FIXED NUMBER of CARRIERS (Controlled By Gate Voltage)
GATE CONTROL of Magnetic Anisotropy
Heisenberg
ST
Q=-1 Q=0 Q=+1 Q=+3
Free
HHLH
Ising ZXX
Mz
KL
LKNMKLMNMN RHi
dt
d,,
, ,
tunneldrainsourcedot VHHHH
N
NNNNNNNNI ,11,11,,
MASTER EQUATION
Scattering Rates
Theory: Single electron transport
Density matrix (Vg, Vb)
2
1, 1 NdNNN
CHARGING the dot
E
Q=0
Q=1
Q=2
VG
VG
Q
Q=0Q=1
Q=2 G
CHARGING the dot
S=3
S=2
Spin dependentCHARGING
ENERGY
3 PEAKS instead of 1 !!
2/5 2/5
2/3 2/3
2/1 2/1
2/1 2/1
2/3 2/3
2/5 2/5
VG
E
25zM
21zM
23zM
2/5 2/5
2/3 2/3
2/1 2/1
2/1 2/1
2/3 2/3
2/5 2/5
VG
E
25zM
21zM
23zM
2/5 2/5
2/3 2/3
2/1 2/1
2/1 2/1
2/3 2/3
2/5 2/5
VG
E
25zM
21zM
23zM
2/5 2/5
2/3 2/3
2/1 2/1
2/1 2/1
2/3 2/3
2/5 2/5
VG
E
Q=0
2/5 2/5
2/3 2/3
2/1 2/1
2/1 2/1
2/3 2/3
2/5 2/5
VG
E
Q=1/3
2/5 2/5
2/3 2/3
2/1 2/1
2/1 2/1
2/3 2/3
2/5 2/5
VG
E
Q=2/3
2/5 2/5
2/3 2/3
2/1 2/1
2/1 2/1
2/3 2/3
2/5 2/5
VG
E
Q=3/3
Inelastic single spin spectroscopy
CONCLUSIONS
Electric Tuning of magnetic anisotropy
Ising ZXX
Mz
www.ua.es/personal/jfrossier/
SPIN conditional charging energy
Q=+1 Q=+3