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

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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

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SPIN conditional charging energy

Q=+1 Q=+3