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
Bessy-II
ELETTRA
Beamline
SISSIIRIS
Beamline
reference orbit: L = 240 m
Take Home
  E Message
3/2
z
III Generation Machines
High
Rep Rate: 500 MHz

DL
CSR
Low-Energy per pulse: pJ
Gl
Several ps bunch length
Needed to compress
the bunch
momentum compaction factor:
I ( )  I (Operation
)[ N  N (N  1)F
( )]
Special
Mode
tot
sp

Linear
Spectroscopy
F ( )  THz
dzS ( z)e
i
Emission in the FIR/THz rangecisz drastically enhanced.
U. Schade et al, PRL 2003
A. Perucchi et al,IP&T 2007
bunch, Dp
Dp/p a = DL/L
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 Superconductors
Superconducting gap observed if:
-sample in the dirty-limit (2D < G)
-Cooper pairs in s-wave symmetry
Minimum excitation energy:
Cooper-pair breaking 2D
1.000
40x10
0.995
R eflectance
2D
0.990
Drude reflectance
     cm -1)
Normal State
T = 0.9 Tc
T = 0.6 Tc
T= 0
3
Normal State
T = 0.9 Tc
T = 0.6 Tc
T=0
30
Drude absorption
G
20

2
ps
8
 (  )   1 ( )
reg
2D
10
0.985
 1 ( ) 
sup
0
0.980
0
20
40
 (cm -1 )
60
80
100
0
50
Superconducting
Gap
100
150
 (cm -1 )
∫ [, T>Tc) - , T<Tc)] dps/8 = nse2/m*--> l=c/ps
Ferrel-Glover-Tinkham Rule
200
0
00
-5
-2
ZFC
FC
-4
-10
Oppenheimer Diamond
254.7 carats
Takenouchi-Kawarada-Takano
Diamond 0.7 carats
0
2
4
T(K)
6
8
 (1 0 - 5e .m .u)
 (1 0 - 4e .m .u)
Superconductivity in Boron doped
Diamond
B-Diamond: a text book example of BCS superconductivity
 ≤ G (T) : Rn () = 1 - [8G(T)/ p2]1/2
 ≤ 2D(T) : Rs() = 1
Peak at 2D in Rs/Rn
 (THz)
0.0
0.2
0.4
0.6
0.8
1.0
1.00
T=2.6K
3.4
4.6
7.2
15
D (c m - 1)
0.95
6
1.05
R s (T ) / R n (1 5 K )
R e fle cta n ce
8
0.90
4
2
Mattis-Bardeen
Model
0
0.0
0.5
1.0
T /T
C
1.00
T=2.6 K
3.4 K
4.6 K
7.2 K
15 K
0.85
20
40
-1
 cm )
60
0
10
20
30
 (cm -1 )
s-wave Dirty-Limit Regime; 2D(0)=12±1 cm-1  2D0/kBTC=3.2 ± 0.5
M. Ortolani et al, PRL, 2006
Mott-Hubbard Insulator to Metal Transitions
Filling-Controlled MIT:
U Coulomb repulsion
t Bandwidth
Bandwidth-Controlled MIT:
• static (pressure)
• static (doping)
Mott-Hubbard Insulator to Metal Transition
Pressure (Bandwidth) controlled MIT
VO2
V2O3
E. Arcangeletti et al, PRL (2007)
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 Dynamically
Photoionization
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
Filling-Controlled MIT:
U Coulomb repulsion
t Bandwidth
• static (Doping)
•Dynamic (Phoexcitation)
Bandwidth-Controlled MIT:
• static (Pressure)
•dynamic (Radiation)
THz pulses in the MV/cm range
can drive lattice displacements
in the pm range
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;
Free Electron Laser SPARC@INFN
Acceleration
section
Beam energy
155–200 MeV
Bunch charge
1 nC
Rep. rate
10 Hz
Peak current
100 A
en
2 mm-mrad
en(slice)
1 mm-mrad
g
0.2%
Bunch length (FWHM) 10 ps-100 fs
Laser
CTR-THz Radiation
Transition Radiation occurs when an electron
crosses the boundary between two different media
Intensity is 0 on axis and peaked at Q~/g
Polarization is radial
Velocity Bunching: Bunch length versus
injection phase
Time
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.
Velocity
Bunching
0.876 ps/mm
t = 160 fs
1.389 ps/mm
t = 2.586 ps
CTR-THz emission
300 fs, 500 pC
500 fs, 250 pC
2 ps
E. Chiadroni et al., J.Phys. 2012
E. Chiadroni et al. APL 2012
S Lupi et al ., J. Phys 2012
M. Ferrario et al., NIM A 2011
CTR measured emission from LINACs
Electron
beam
energy
Charge
Dt
(bandwidth)
THz pulse
energy
E-field
Brookhaven(1)
120 MeV
~ 1 nC
(2 THz)
≈100 J
MV/cm
SPARC(2)
120 MeV
500 pC
120 fs
(10 THz)
≈100 J
MV/cm
FLASH(3)
1.2 GeV
600 pC
(4 THz)
>100 J
MV/cm
LCLS(4)
14.5 GeV
350 pC
50 fs
(40 THz)
140 J
>20 MV/cm
(1) Y.
Shen et al., Phys. Rev. Lett. 99, 043901 (2007)
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)
(2) E.
Perspectives
• Increase machine energyincrease of bunch-charge (1 nC);
• Tailoring the electronic bunch shapeextended spectral coverage
(20 THz);
• Narrow band THz radiationSmith-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