D.N. Basov Department of Physics University of California, San Diego
Low Frequency Dynamics of Correlated Electron Systems
NSLS-II workshop March 15, 2004
Doped Mott-Hubbard Insulators spectral weight transfer spin/charge inhomogeneities
High-Tc superconductors inhomogeneous condensate pairing “glue” energetics2D electron gas and FET structures magnetic organic FET
IR @NSLS-II
Experimental issues New opportunities
Low Frequency Dynamics of Correlated Electron Systems
D.N. Basov Department of Physics University of California, San Diego
Magnetism inter-metallic ferromagnets ferromagnetic semiconductors magnetic resonances left-handed media
Sub-THz Far-IR mid-IR - visible UV
10 100 1000 10000 cm-1
1 10 100 1000 meV
“Infrared” spectroscopy @ UCSD
Low Frequency Dynamics of Correlated Electron Systems
pseudogaps
superconducting energy gap carrier lifetimes in correlated systems
collective modes in correlated systemsphonons
electronic transitions
1 10 100 1000 10000 cm-1
100 1000GHz 100 1000meVIR s e trosco UCSD
IR spectroscopy @ UCSD
2D Electron gas: EF
(magnetic) polarons
Cyclotron resonances
pseudogaps
superconducting energy gap carrier lifetimes in correlated systems
collective modes in correlated systemsphonons
electronic transitions
1 10 100 1000 10000 cm-1
100 1000GHz 100 1000meVIR s e trosco UCSD
IR spectroscopy @ UCSD
2D Electron gas: EF
(magnetic) polarons
Cyclotron resonances
1. Broad spectral coverage
2. Optical constants and sum rules
3. Anisotropy
4. Large probing thickness
5. Micro-crystals
: σσσσ1111(ω)(ω)(ω)(ω) + + + + iσσσσ2222(ω)(ω)(ω)(ω)
Low Frequency Dynamics of Correlated Electron Systems
6. Extreme experimental conditions:mK temperatureshigh magnetic fieldhigh electric fieldultra-high pressure
0 2 4 6eV
0
1000
2000
3000
D:\talks\2002\all-meeting-may\mott-hubba
0 2 4 6 eV
0
1000
2000
3000
0 1 2 3 4eV
0
400
800
1200
10 K
σ(ω), [Ωcm]-1 σ(ω), [Ωcm]-1 σ(ω), [Ωcm]-11. Doped Mott-Hubbard Insulators
6 eV 6 eV 4 eV
La2-xSrxCuO4La1-xSrxVO3La1-xSrxMnO3F.Inaba et al.PRB 52, 2221 (95)
Y.OkimotoPRB 51, 9581 (95)
S.Uchida et al.PRB 43, 7942 (91)
Experimental issues: High-ωωωω data is needed for KK analysis
R(ωωωω) data at ωωωω < 36 eV
x=0
x=0.34
x=0x=0
x=0.4x=0.3
Beam-line based ellipsometry
IR @NSLS-II
2. Doped Mott-Hubbard Insulators: T dependence
V2O3M.Rozenberg et al.PRL 75, 105 (95)
170 K
300 K
70 K
0.0 0.4 0.8 1.2 1.6eV
0
1000
2000
3000
σ(ω), [Ωcm]-1
Experimental issues: T, H dependence of σ(ω)σ(ω)σ(ω)σ(ω)over anomalously broad ωωωω range
Accurate data over broad ωωωω intervals Beam-line based ellipsometry
( )em
nd =∫∞
ωσω 10
IR @NSLS-II
3. Doped M-H Insulators: charge inhomogeneities
CuO2
CuO2
CuO2
⊥EIIE
0 100 200 300
0
500
1000
0 100 2000
500
1000
a axis b axis
Temperature (K)
σdc (Ω
-1cm-1)
13 K a axis b axis
σ1 (Ω
-1cm-1)
Frequency (cm-1)
II⊥
II⊥
La1.96Sr0.04CuO4
M.Dumm, S.Komiya, Y.Ando, D.N.Basov, PRL 91, 077004 (03).
IR @NSLS-II
Experimental issues: Micro-crystals
High intensity, Beam-line based IR microscopy Photo-inducedeffects
CuO2
CuO2
CuO2
0.5 1.0 1.5 ω/ω0
0.04
0.08
0.12
0.16
Im(1
/ε)
6 K
20 30 40 50 cm-1
0.5
1.0
R(ω
)
6 K
S.Dordevic, S.Komiya, Y.Ando, D.N.Basov, PRL 91, 167401 (03)
“Josephson plasmon microscopy”
4. Doped MH Insulators: inhomogeneous superconductivity
0
0.02
0.04
0.06
0.08
Im(1
/ε)
R(ω
)
15 K
GHz
cm-1
0.5 1.0 1.5 ω/ω0
0.04
0.08
0.12
0.16
Im(1
/ε)
6 K
20 30 40 50 cm-1
0.5
1.0
R(ω
)
6 K
E.J.Singley et al. PRB (in press)ALS-BESSY collaboration
“Josephson plasmon microscopy”
Experimental issues: Sub-THz ωωωω region
IR @NSLS-II
“coherent” radiation
S.Dordevic, S.Komiya, Y.Ando, D.N.Basov, PRL 91, 167401 (03)
4. Doped MH Insulators: inhomogeneous superconductivity
0 400 800 1200 1600 cm-1
0
1
2
W(ω
)
neutron
W(ω)
5. High-TC superconductivity: pairing interaction
Experimental issues: Second derivative of 1/τ(ω)/τ(ω)/τ(ω)/τ(ω)
0 40 80 120 160cm-1
0
0.4
0.8
1.2
As
An
R.R.Joyce and P.L. Richards PRL 24, 1007 (67)
Beamline-based ellipsometry
Magnetic? P.D.Johnson RPL 87, 177007 (01), Hwang et al. Nature (04)consistent with ARPES, tunneling,
Phonons? /A.Lanzara et al. Nature 412, 510 (2001)/… but no isotope effect /N.Wang et al. PRL 89, 87003 (03)
J.Carbotte, E.Schachinger, D.N.BasovNature 401, 354 (1999)
Phonon DOS(neutrons)
( ) ( )
=ωσ
ωωπ
ω 1Re21
2
2
ddW
Pb
IR @NSLS-II Magneto-optics
H.J.A.Molengraaf et al. Science 295, 2239 (2002)
gordon/fig/form-for-fig4-all
kinetic energy sum rule
∫σ1
W
0dω = −Kr
6. High-TC superconductivity: energetics at T<<TC
Experimental issues:Small effects involving broad ωωωω range
La2-xSrxCuO4
YBa2Cu3O6.6
0 500 1000 cm-1
0.0
0.5
1.0
[Nn(ω
) - N
s(ω )]
__
____
____
__
ρs
0.0
0.5
1.0
56 kTc
Nn(ω
) - N
s(ω )
____
____
____
ρ
s
0 40 80 120 meV
22 kTc
Synchrotron-basedellipsometry
IR @NSLS-II
D.N. Basov, S.I. Woods, A.S.Katz, E.J. Singley,R.C. Dynes, M. Xu, D.G. Hinks, C.C. Homes, M.Strongin, Science 283, 49 (1999)
10 100 T, (K)N
eff
0
10
20
30
M(T
), (e
mu/
cm3 )10 100 T, (K)
2000300040005000
ωp
cm-1
EuB6L.Degiorgi et al.PRL 79, 5134 (97)
Ga1-xMnxAsE.J.Singley, PRL89, (2002)
Y.Okimoto et al.PRL 75, 109 (95)
0 100 200 300 T, (K)0.000.020.040.06
Nef
f
0.00.20.40.60.81.0
M(T
)/M0La1-xSrxMnO3
La1-xSrxMnO3
Experimental issues:Bandwidth? “Undressing” effect?
Beamline-based ellipsometry
7. Magnetism: itinerant intermetallic ferromagnets
IR @NSLS-II
8. Magnetism: optical control of magnetic state
S.Koshihara et al. PRL78, 4617 (1997)
In1-xMnxAs
A.Oiwa, Y.Mitsumori, T.Slupinski, H.Munekata,PRL 88, 137202 (2002)
IR @NSLS-II
Pump-probe experiments
AF
9. Magnetism: AF resonance in the frequency domain
Experimental issues:Sub-THz regionSmall transmission
Intensity! IR @NSLS-II
LaMnO3
L. Mihály, D. Talbayev, L. F. Kiss, J. Zhou, T. Fehér, and A. Jánossy Phys. Rev. B 69, 024414 (2004)
10. Magnetic resonances and “Left-handed” media
D.R.Smith et al.PRL 84, 4184 2000
(+,+)(-,+)
(-,-) (+,-)
ε,µε,µε,µε,µ space
V.G.VeselagoSov. Phys. Uspekhi 10, 509 (1968)
Irrelevant?Split-ring resonator design J.B. Pendry et al. PRL 76, 4773 (1996)
10. Magnetic resonances and “Left-handed” media
(+,+)(-,+)
(-,-) (+,-)
ε,µε,µε,µε,µ space
T.J. Yen, et al. Science 303, 1494 (04)
Experimental challenges:1. Tunable?• Real materials?
IR @NSLS-II
Photo-dopingFET-dopingIR ellipsometry
11. FET structures:
H. Ohno, D. Chiba, F. Matsukura, T. Omiya, E. Abe, T. Dietl, Y. Ohno& K. Ohtani, Nature 408, 944 (2000).
pentacene Poly(3-hexylthiophene)
V.Y. Butko*, X. Chi, D. V. Lang,A.P. Ramirez APL 83, 4773 (03)
G. Wang, D. Moses, A.J. Heeger,J. Applied Phys. 95, 316 (04)
FM semiconductors
Organic molecular crystals
Polymers
pentacene Poly(3-hexylthiophene)
V.Y. Butko*, X. Chi, D. V. Lang,A.P. Ramirez APL 83, 4773 (03)
G. Wang, D. Moses, A.J. Heeger,J. Applied Phys. 95, 316 (04)
H. Ohno, D. Chiba, F. Matsukura, T. Omiya, E. Abe, T. Dietl, Y. Ohno& K. Ohtani, Nature 408, 944 (2000).
11. FET structures
gateoxide
CRYSTAL
IR INTERFEROMETER
detector
S D
Spectroscopy @ NSLS-2 and Correlated Electron Systems
IR• Instruments for broad range spectroscopy: (80 GHz - 30 eV )
• “Coherent” radiation for sub-THz region
• Spectroscopic ellipsometry
• Pump-probe experiments
• Micro-sample capabilities
• High magnetic field