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Electrical control of a single Mn atom in a QD J. Fern ndez-Rossier Department of Applied Physics, U. Alicante SPAIN February 2006 University of Alicante, Spain – PowerPoint PPT presentation

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Title: Electrical control of a single Mn atom in a QD


1
Electrical control of a single Mn atom in a QD
J. Fernández-Rossier
Department of Applied Physics, U. Alicante SPAIN
February 2006
University of Alicante, Spain
www.ua.es/personal/jfrossier/
2
(No Transcript)
3
Outline
Single EXCITON Spectroscopy
CdTe QD 1 Mn
CdTe QD
CdTe QD 1 Mn1 e
L. Besombes et al., PRL 93, 207403, 04
Y. Léger et al., PRL 97,07401 (06)
L. Besombes et al., PRL 93, 207403, 04
  1. Optics QD Hamiltonian for 1 Mn electrons
    holes
  2. Transport single ELECTRON Spectroscopy
  3. Magnetism Mn 1 hole single atom nanomagnet

International Workshop on Quantum-Dot
Spintronics December 7-8, 2006, Ruhr-Universität
Bochum, Germany
4
PEOPLE
R. Aguado
L. Brey
Y.Leger L.BesombesL.Maingault H.Mariette
Laboratoire de Spectrométrie Physique, GRENOBLE,
France. Equipe CEA-CNRS Nanophysique et
Semi-conducteurs Laboratoire Louis Néel, CNRS
GRENOBLE, France.
5
Background
6
Single exciton in Mn-doped II-VI QD
ZnSe QD many Mn
CdTe QD 1 Mn
CdTe QD many Mn
10 meV
A. A. Maksimov, et al., Phys. Rev. B 62, R7767
(00)
L. Besombes et al., PRL 93, 207403, 04
G. Bacher et al. PRL. 89, 127201 (2002)
7
Neutral CdTe QD 1 Mn
6 Lines
CdTe QD 1 Mn
L. Besombes et al., PRL 93, 207403, 04
THEORY J. Fernández-Rossier, PRB73, 045301 (06)
8
Basic Notions
Cd 3d10 4s2 Mn 3d5 4s2
Mn replaces Cd Mn2
Mn2 S5/2, 2S16
EXCHANGE INTERACTIONS
SPIN DENSITY
  • Mn - CB electron
  • Mn - VB hole
  • Mn-Mn Short range AF

QD affects both SYMMETRY and Amplitude
9
Basic Notions Q0 states
Size of Hilbert space6
np0
10
Basic Notions Q-1 states
Size of Hilbert space12
n1, p0
S2
Heisenberg
S3
SSeM
11
Basic Notions Q1 states
Size of Hilbert space12
Mz,Sz
n0, p1
Ising
12
Q0 EXCITON states
6 Doublets
Size of Hilbert space24
13
EXCITON states
a
a
a
Photon polarizationMn spin polarization
Size of Hilbert space24
14
EXCITON states
b
a
b
b
Size of Hilbert space24
15
EXCITON states
Photon Energy Polarization Mn spin measurement
Size of Hilbert space24
16
Full theory Single exciton spectroscopy (1 Mn
dot)
EXPERIMENTS Y. Léger et al. PRL 95, 047403 (05)
WE UNDERSTAND ehMn
THEORY J. Fernández-Rossier, PRB73, 045301 (06)
17
Charged CdTe QD 1Mn
11 Lines
Vb
Gated CdTe QD 1 Mn
Y. Léger, L. Besombes, J. Fernández-Rossier, L.
Maingault, H. Mariette PRL 97,07401 (06)
18
Charged exciton states (1 Mn dot). Q-1
PL diagram
Trion State
12 Trion States
Full Shell
a
b
b
Exp.
a
a
S2
b
S3
12 ground states
19
Charged exciton states (1 Mn dot). Q1
PL diagram
Ground State
Trion State
12 Trion States
Full Shell
Q1
Q1
Loosely bound Hole
Small Jh
12 ground states
20
Electrical Control of the Ground State spin
Ground State
Ground State
Full Shell
Q0
Q1
Q-1
21
Electrical Control of the Ground State spin
Ground State
Ground State
Full Shell
Nanomagnet
Paramagnet
Superparamagnet
Ising
Heisenberg
S2
S3
22
Single Electron Transport
VG
I
Vb
  1. Electrically tunable nanomagnet
  2. Probing the magnetism upon current flow.

Single Electron transport in Tunable nanomagnets
JFR, R. Aguado, cond-mat/0604437
23
Related Work
Remanent Zero Field Spin Splitting of Self
Assembled QD.., C. Gould et al. Phys. Rev. Lett.
97, 017202 (06)
24
Theory Single electron transport
Same Hamiltonian than OPTICS
STATES WITH a FIXED NUMBER of CARRIERS
COMPUTE RATES. SPIN FRANK-CONDON
Obtain QD density matrix SOLVE MASTER EQUATION
for Vg and Vb, T
Compute Charge, Current, Spin
25
QD STATES
GATE CONTROL of single atom Magnetic Anisotropy
ST
Mz
Ising
Heisenberg
ZXX
Free
HH
LH
Q-1
Q0
Q1
Q3
26
Transport Hysteretic Linear Conductance
Vb
I?0
I0
VG
N-1
N
N1
27
Reminder of Coulomb Blockade
E
Q2
Q1
Q0
VG
Q
G
Q2
Q1
Q0
VG
28
Charging curves for the Mn-doped dot
CB electron
VB Hole
3 PEAKS instead of 1 !!
Standard Results
HYSTERESIS in G0
29
Hole injection in the Mn-doped dot
No spin flip T1? (sim.) T1gt1ms (exp)
30
Some LH-HH Mixing 2 peaks and Hysteretic
Charging curves
2 Peaks when for Realistic value of spin flip
Small spin flip T1? (sim.) T1gt1ms (exp)
31
Hysteretic Charging curve for LH
Hysteresis For in-plane easy axis
No spin flip T1? (sim.) T1gt1ms (exp)
32
Finite Bias zero field spin splitting
Vb
I?0
I0
VG
N-1
N
N1
33
Inelastic single spin spectroscopy electrons
ZERO FIELD SPLITTING
EXP
S2
S3
S2
S3
C. Gould et al. Phys. Rev. Lett. 97, 017202 (06)
34
Inelastic single spin spectroscopy holes
35
CHARGED Mn-doped QD NANOMAGNET
Vb
36
ERGODIC MAGNETISM 1Mn 1hole
MAGNETIC ANISOTROPY
Nanomagnet
Ising
37
Mn1h NANOMAGNET
Spectrum (meV)
Initial State
Mn T110ms MnHole???
ltMgt
Non Ergodic Magnetization
Remanence and Hysteresis
38
OUTLOOK QD AMPLIFIES the Mn spin quantum state
104 CdTe atoms 1 Mn
5nm
L. Besombes et al., PRL 93, 207403, 04
39
CONCLUSIONS
CdTe QD 1 Mn
Measuring the quantum state of a single spin
Electrical Tuning of the MAE of a single atom
Hysteretic Linear Conductance
Y. Léger,L. Besombes, J. Fernández-Rossier, L.
Maingault, H. Mariette PRL 97,07401 (06)
JFR, R. Aguado, cond-mat/0604437
www.ua.es/personal/jfrossier/
40
Thanks for your attention
POSTDOC OFFER FOR ALICANTE Contact me right now
(Deadline 15-12-06)
www.ua.es/personal/jfrossier/
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