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Linear and Pump-Probe applications of THz Spectroscopy: The case of
Elettra, Bessy-II, and SPARC
S. Lupi Dipartimento di Fisica, INFN-University of Rome La Sapienza, and SISSI@ELETTRA,
Italy
SISSI
Synchrotron Infrared Source for Spectroscopy and Imaging
Outline
• THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra;
• THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials;
• Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials;
• High-Power/Sub-ps THz Pulses @SPARC;
Outline
• THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra;
• THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials;
• Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials;
• High-Power/Sub-ps THz Pulses @SPARC;
THz Coherent radiation production from III Generation Machines: Bessy-II and Elettra
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Itot (ω) = Isp (ω)[N +N(N −1)F(ω)]
F(ω) = dzS(z)eiω
cz
∫Emission in the FIR/THz range is drastically enhanced.
Bessy-IIIRIS Beamline
U. Schade et al, PRL 2003
A. Perucchi et al,IP&T 2007
ELETTRASISSI Beamline
€
σz ≈ E 3 / 2
CSR
Gl
Take Home Message
III Generation MachinesHigh Rep Rate: 500 MHzLow-Energy per pulse: pJSeveral ps bunch length
Needed to compress the bunchSpecial Operation Mode
Linear THz Spectroscopy
Outline
• THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra;
• THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials;
• Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials;
• High-Power/Sub-ps THz Pulses @SPARC;
Superconductivity today:
THz spectroscopy plays a fundamental role
... because
Superconductivity is ruled by low-energy electrodynamics:
• Superconducting gap : THz range• Spectral weight of condensate and penetration depth: THz
• Mediators of pairing (phonons, etc.): THz• Range of sum rules: THz, Mid, or Near Infrared
• Free-carrier conductivity above Tc: Infrared
Basic optics of SuperconductorsSuperconducting gap observed if:-sample in the dirty-limit (2 < )
-Cooper pairs in s-wave symmetry
σ1
sup
( ω ) =
ω
2
ps
8
δ ( ω ) + σ1
reg
( ω )
∫ [σ, T>Tc) - σ, T<Tc)] d ps/8 = nse2/m*--> =c/ps
Ferrel-Glover-Tinkham Rule
40x103
30
20
10
0
σ
() (Ω
−cm-1
)
200150100500
ω (cm-1)
Normal State T = 0.9 Tc T = 0.6 Tc T = 0
Superconducting Gap
1.000
0.995
0.990
0.985
0.980
Reflectance
100806040200
(cm-)
Normal State = 0.9 T Tc = 0.6 T Tc = 0 T
Drude absorption
Drude reflectance
2
Minimum excitation energy:Cooper-pair breaking 2
Superconductivity in Boron doped Diamond
Oppenheimer Diamond 254.7 carats
Takenouchi-Kawarada-Takano Diamond 0.7 carats
86420
ZFC FC
-5
-10
0
μ (0-4
. . )e m u μ (0
-5
. . )e m u
00
-
-4
( )T K
B-Diamond: a text book example of BCS superconductivity
s-wave Dirty-Limit Regime; 2(0)=12±1 cm-1 20/kBTC=3.2 ± 0.5
1.05
1.00
3020100
1.00.80.60.40.20.0
T=2.6 K 3.4 K 4.6 K 7.2 K 15 K
8
6
4
2
01.00.50.0
(cm-)
/ T TC
( )THz
Rs
( ) / T R
n
(5 ) K
(cm-)
Mattis-Bardeen Model
≤ (T) : Rn () = 1 - [8(T)/ p2]1/2 ≤ 2(T) : Rs() = 1
Peak at 2 in Rs/Rn
M. Ortolani et al, PRL, 2006
1.00
0.95
0.90
0.85604020
(cm-)
=.6 T K 3.4 4.6 7. 5
Mott-Hubbard Insulator to Metal Transitions
Filling-Controlled MIT:• static (doping)
Bandwidth-Controlled MIT:• static (pressure)
U Coulomb repulsiont Bandwidth
Mott-Hubbard Insulator to Metal Transition
E. Arcangeletti et al, PRL (2007)
VO2
Pressure (Bandwidth) controlled MIT
V2O3
Outline
• THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials;
• THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra;
• Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials;
• High-Power/Sub-ps THz Pulses @SPARC;
Breaking Cooper Pairs DynamicallyPhotoionization
For hω>2Δ light breaks Cooper pairs
1) Optical Pump - Optical Probe (THz Probe) hω>>2Δ Recombination Dynamics affected by excess phonons
2) THz Pump – THz Probe hωTHz≥2Δ Intrinsic dynamics
Alternative processes if hω<2Δ Δ=Δ(J, B) at fixed T<Tc
The high E (~MV) THz field may induce currents exceeding the critical current (breaking the Superconducting State with an Electric Field)
The high B (~1 T) THz field may be larger that Bc(breaking the Superconducting State with a magnetic Field)
THz controlled Mott-Hubbard MIT
THz pulses in the MV/cm range can drive lattice displacements
in the pm range
Filling-Controlled MIT:• static (Doping)•Dynamic (Phoexcitation)
Bandwidth-Controlled MIT:• static (Pressure)•dynamic (Radiation)
U Coulomb repulsiont Bandwidth
Dynamical modulation of U through intramolecular pumping
Outline
• THz Linear Spectroscopy: Applications in Superconductivity and Strongly Correlated Materials;
• THz Radiation production from III Generation Machines: the case of Bessy-II and Elettra;
• Pump-Probe THz Experiments in Superconductivity and Strongly Correlated Materials;
• High-Power/Sub-ps THz Pulses @SPARC;
Acceleration section
Ondulator S
ection
THz Section
Laser
Free Electron Laser SPARC@INFNBeam energy 155–200 MeVBunch charge 1 nCRep. rate 10 HzPeak current 100 An 2 mm-mradn(slice) 1 mm-mradσ 0.2%Bunch length (FWHM) 10 ps-100 fs
Transition Radiation occurs when an electroncrosses the boundary between two different media
Intensity is 0 on axis and peaked at Polarization is radial
CTR-THz Radiation
Velocity Bunching: Bunch length versus injection phase
If the beam injected in a long accelerating structure at the crossing field phase and it is slightly slower than the phase velocity of the RF wave , it will slip back to phases where the field is accelerating, but at the same time it will be chirped and compressed.
0.876 ps/mm
σt = 160 fs
Velocity Bunching
1.389 ps/mm
σt = 2.586 ps
Tim
e
CTR-THz emission
500 fs, 250 pC
300 fs, 500 pC
2 ps
E. Chiadroni et al., J.Phys. 2012E. Chiadroni et al. APL 2012 S Lupi et al ., J. Phys 2012M. Ferrario et al., NIM A 2011
CTR measured emission from LINACsElectron
beam energy
Charge t
(bandwidth)
THz pulse energy
E-field
Brookhaven(1) 120 MeV ~ 1 nC -
(2 THz)
≈100 μJ MV/cm
SPARC(2) 120 MeV 500 pC 120 fs
(10 THz)
≈100 μJ MV/cm
FLASH(3) 1.2 GeV 600 pC -
(4 THz)
>100 μJ MV/cm
LCLS(4) 14.5 GeV 350 pC 50 fs
(40 THz)
140 μJ >20 MV/cm
(1) Y. Shen et al., Phys. Rev. Lett. 99, 043901 (2007)(2) E. Chiadroni, et al., APL 2012(3) M.C. Hoffmann et al., Optics Letters 36, 4473 (2011)
(4) D. Daranciang et al., Appl. Phys. Lett. 99, 141117 (2011)
Perspectives
• Increase machine energyincrease of bunch-charge (1 nC);• Tailoring the electronic bunch shapeextended spectral coverage
(20 THz);• Narrow band THz radiationSmith-Purcell Radiation:
Narrow-band and Tunable THz Radiation
Acknowledgments
• A. Perucchi (SISSI@ELETTRA)• E. Karanzoulis (ELETTRA)• U. Schade (IRIS@BESSY-II)• E.Chiadroni and M. Ferrario (LFN-INFN):
TERASPARC project
Thank for your attention