Nan0-Science and Engineering in Superconductivity

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Intense, Coherent and Continuous THz Electromagnetic Waves from THz Electromagnetic Waves from

High High - - T T _{c c} Superconductor Bi Superconductor Bi _{2 2} Sr Sr _{2 2} CaCu CaCu _{2 2} O O _{8+ 8+ δ δ} Single Crystal Mesa Structures

Single Crystal Mesa Structures

1

K. Kadowaki, H. Yamaguchi, K. Yamaki, M. Tsujimoto, T. Yamamoto, H. Minami, T. Hattori, I. Kakeya

, M. Tachiki

, H. Matsumoto*, T. Koyama*, M. Machida

Institute of Materials Science, and Graduate School of Pure and Applied Sciences, University of Tsukuba

#

Department of Electronic Science and Engineering, Graduate School of Engineering, Kyoto University

$

Graduate School of Frontier Sciences, University of Tokyo

*Institute for Materials Research, Tohoku University

%

Center for Promotion Computational Science and Engineering, JAERI, Japan L. Ozyuzer

, A. E. Koshelev, C. Kurter

, K. E. Gray, W. –K. Kwok and U. Welp

+

Department of Physics, Izmir Institute of technology,

&

Physics Division, Illinois Institute of Technology, Materials Science Division, Argonne National Laboratory

and Richard Klemm

Department of Physics, University of Central Florida

Presented at the TNT (Trends in NanoTechnology) 2008, Oviedo, Spain, September 1-5, 2008

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Outline Outline

¾ THz waves and THz gap

¾ Single crystals

¾ Observation of THz emission

¾ Emission of electromagnetic waves

¾ Experimental setup

¾ Mesa structures

¾ Two mechanisms: STAR-emitter and CASER

¾ Applications

¾ summary

２ Reference;

Ozyuzer et al., Science, 318 1291 (2007).

K. Kadowaki, et al., Physica C 468, 634-639 (2008).

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

10 ⁰ 10 ³ 10 ⁶ 10 ⁹ 10 ¹² 10 ¹⁵ 10 ¹⁸ 10 ²¹ 10 ²⁴ kiro mega giga tera peta exa zetta yotta

THz THz

10 ¹⁰ 10 ¹¹ 10 ¹² 10 ¹³ 10 ¹⁴

FIR MIR NIR visible

frequency 10[GHz] 100[GHz] 1 [THz] 10[THz] 100 [THz]

wave length 3[cm] 3[mm] 300[μm] 30[μm] 3[μm]

wave number 0.33[cm

] 3.3[cm

] 33[cm

] 330[cm

] 3300[cm

]

Molecular Spectroscopy Atomic spectroscopy

Macromolecule fundamental mode electronic transition rotational mode higher harmonics MF VHF SHF

HF UHF EHF microwave

Electronics

Electronics Photonics Photonics

x-ray γ-ray

３

FREQUENCY (Hz)

FREQUENCY (Hz)

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

THz gap

0.01 0.1 1.0 10 100

10 ^-3 10 ⁰

10 ^-1

10 ^-2

10 ^-4 10 ¹ 10 ² 10 ³

Power (mW)

Frequency (THz)

THz gap THz gap

O p ti c s

P h o to n ic s E le

c tro n ic s

p h o to

m ix in g

Q u a n tu m c a s c a d e l a s e r

II I- V l a G u n n

PA TT

Intrinsic Josephson LASER (TASER)

10 100

1 1000 (cm

)

Microwaves Far infrared light

４ present stage

After M. Tonouchi, Nature Photon. 1, 97 (2007).

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Intrinsic Josephson Junctions:

Intrinsic Josephson Junctions:

Crystal Structure Crystal Structure

1.53 nm

Bi-2212 order parameter ψ

Bi

O

Bi

O

CuO

CuO

CuO

CuO

CuO

CuO

SrO

SrO

SrO

SrO

| ψ | ²

Intrinsic inhomogeneity

I

V

I-V characteristics in conventional planer

junctions I-V Characteristics

in IJJ’s

multilayer effects

1 μ m corresponds to n~760

unit cell of Bi2212

５

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Rocking Curve Single Crystal Large anisotropy parameter γ

underdope overdope γ~1000 γ~80

IJJ’s are densely packed at the atomic level!

６

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Photo of the sample by SEM Schematic view of the sample

THz waves THz waves

Mesa Structures Mesa Structures

７ 1. Conventional mesa

2. Z-type mesa

H

l t

w

c ab

3. Groove type mesa

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Experimental Results Experimental Results

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5

-0.02 -0.01 0.00 0.01

0.02 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5

5400 5600 5800 6000 6200 6400

I (A )

V (V)

Intensity [a.u.]

07/07/05

T = 35 K

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

THz Emission THz Emission

L (μm) w (μm) d (μm) f _cal (GHz)

f _obs (GHz)

2f _obs (GHz)

3f _obs (GHz)

4f _obs (GHz)

300 100 1.0 358 357 - - -

300 80 1.0 447 480 990 - -

300 60 1.0 597 560 - - -

400 60 ∼ 2 597 624 1249 - -

400 60 ~1.0 597 648.3 1296 1944 2589

300 40 1.0 894 870

８

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Experimental Setup Experimental Setup

９ Si-Bolometer

simultaneous detection

Si-Bolometer FTIR-Spectrometer

Cold Finger Sample Chopper Shutter Heater

Thermometer He flow cryostat

Guide

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

I I - - V V Characteristics and Characteristics and THz Detection

THz Detection

Heating effect

１０

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

More Recent Works More Recent Works

• E. Kume, et al., Appl. Phys. Lett 75 (1999) 2809.

– film, in zero field, no cavity

• I. Iguchi, et al., Phys. Rev. B62 (2000) 5370.

– P _out ~1 μw, YBCO film, zero field, no cavity

• K. Lee, et al., Phys. Rev. B61 (2000) 3616.

– YBCO film, zero field, no cavity

• I. E. Batov, et al., Appl. Phys. Lett. 88 (2006) 262504.

– P _out =~pW, BSCCO, zero field, no cavity

• K. Kadowaki, et al., Physica C 437-438 (2006) 111.

– P _out =~mW, BSCCO, Xtal, in fields

• M. H. Bae, et al., Phys. Rev Lett. 98 (2007) 027002.

– P _out =~nW, BSCCO, Xtal, in fields

c.f.

Blog Yamashita: http;//tyamasuper.exblog.jp/

１１

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Radiation Radiation Power

Power P P vs. vs. n n

１２

n 2

P _rad ∝

Coherent Radiation!

single layer JJ： P _single ^~ pW

multilayered IJJ：

P _IJJ ≥ μW - mW

１０ ⁵ -10 ⁶ times more power!

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Radiation Spectra Radiation Spectra

1 0 1 1 1 2 1 3 1 4

0 5 0 1 0 0 1 5 0 2 0 0

In te nsity (a .u.)

w a v e n u m b e r k (c m ^{- 1} )

0 7 / 0 7 / 1 1 K K 0 3 T = 4 0 K A 0 7 1 1 2 3 3 8

V = 0 .8 2 6 V

Δk= 0 .3 7 4 cm

Δk/k= 0 .0 3 1 6

In s tru m e n ta l re s o lu tio n lim it

very sharp

１３ Δ k=0.25 cm ^-1

Δ f=7.5 GHz

(11.2 GHz)

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Temperature Dependence Temperature Dependence

Emission occurs only in a limited temperature region ! Emission occurs only in a limited temperature region !

１４

Non-equilibrium state is important for radiation!

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

New Data New Data

0 10 20 30 40 50 60

0.0 0.5 1.0

N o rmalized Int ensit y (arb.)

T (K)

(A)

(B) (C)

１５

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Angular Dependence (I) Angular Dependence (I)

0 1 2 3 4 5

0 30 60

90 120

150

180

210

240

270

300

330

0 1 2 3 4 5

Intensity [mV]

in ab-plane

１６

θ

ｘ φ

ｙ ｚ

r

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Angular dependence (II) Angular dependence (II)

0 /

) 90 ( , 90

) 0 ( 5 . 0 /

) 0 ( , 0

max max

=

=

≠

≈

=

I I

I I

o o

θ

θ Contradictory to

the simple dipole model!

１７

Dipole radiation movie

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Simulation (I) Simulation (I)

(Matsumoto, Koyama, Machida) (Matsumoto, Koyama, Machida)

Lx/λc=2.0,β=0.05,βL=100.0, jext/jc=0.8

E _z /E _p

x

z z

x

１７

Electric Field

Electric Field

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Simulation (II) Simulation (II)

j _ext /j _c =0.3 j _ext /j _c =0.2

Lx/λc=3.0, Ly/λc=1.0,β=0.05, ε=10.0 x

y y

x

１９

Magnetic field

Magnetic field

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Simulation (III) Simulation (III)

S

/S

S

/S

L

/λ

=1.0 L

/λ

=0.25 W

/λ

=0.2 L

/λ

=3.5

V/V

=3.15

L

/λ

=1.0 L

/λ

=1.0 L

/λ

=0.25 W

/λ

=0.2 L

/λ

=3.5

L

/λ

=3.0

0 2e-05 4e-05 6e-05 8e-05 0.0001 2e-05

4e-05 6e-05 8e-05 0.0001

L _sub

S

/S

S

/S

L

/λ

=1.0 L

/λ

=0.25 r

/λ

=3.0 V/V

=5.83

0 5e-05 0.0001 0.00015

5e-05 0.0001 0.00015

S

/S

S

/S

L

/λ

=1.0 L

/λ

=3.0 r

/λ

=3.0

V\V

=5.84

0 2e-05 4e-05 6e-05 8e-05 0.0001 2e-05

4e-05 6e-05 8e-05 0.0001

Au substrate Bi2212 mesa

model

２０

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Possible Excitation Modes Possible Excitation Modes

Symmetric Anti-symmetric

Dipole radiation-like E: linearly polarized

Cancelling dipole radiation E: linearly polarized

２１

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Frequency vs. sample width Frequency vs. sample width

10 20 30

200 400 600 800 1000

Fr equency f (GH z )

1/w ⁽ cm-1 ⁾ frequency f vs 1/width w

30 40 50 60 70 80 90 100 110 120 200

300 400 500 600 700 800 900 1000

Frequency f (GHz)

Width w

μ m

２２

λ n

c nw

f c ^{0 0} 2 =

=

refractive index n=4.19

dielectric constant ε =4.19 ² =17.53

standing wave

sample plays as a cavity

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Frequency vs. voltage

0.75 0.76 0.77 0.78 0.79 0.80 0.81 0.82 0.83 300

400 500 600 700

Frequency f (GHz)

Voltage (V)

KK24, T=20 K 2e/h=483.5940 GHz/mV

Same slope Same slope

２３ v=V/N

f: frequency V: total voltage

N: number of layers v: voltage for single

junction f(GHz)=483.5940(GHz/mV) x v

N=672.4 layer (corresponding to 1.03 μ m thickness) (653.6 layer/1 μ m) ac Josephson

effect!

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

AC Josephson effect AC Josephson effect

– Single junction

ac Josephson effect

Experiments (Indirect)

S. Shapiro, PRL 11, 80 (1963), S. Shapiro, et al., Rev. Mod. Phys. 36, 223 (1964), I. Giaever, PRL 14, 904 (1965).

Direct measurements

I. K. Yanson, V. M. Svistunov and I. M. Dmitrenko, ZhETF, 48, 976 (1965), D. N. Langenberg, et al., PRL 15, 294 (1965).

Theory

B. D. Josephson, Phys. Lett. 1, 251 (1962).

２４ λ λ Josephson junction

ϕ

ϕ

2

1 ϕ

ϕ ϑ = − V _dc d

eV t ( = = h ) = 2

∂

∂ ϑ ω ν

h h

483 .

0

0

=

= φ

ν ^{V dc} THz/mV

15 0 ( = h / 2 e ) = 2 . 067833636 × 10 ⁻

φ Wb

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

A

B θ

θ θ = −

0

2

θ ω

θ θ

+

=

∴

=

t e V dt

d

J

h dc

0

2

φ ^dc

dc V

h

f = eV = h

eV

J

= 2 ω

Multi-stacked Josephson junction

Giant Josephson junction ϕ

ϕ

2

1

ϕ

ϕ ϑ = −

V _dc

P∝N ² ac-Josephson Effect

Similar to LASER ^５

N layers

E ₁ E ₂

1

2 E

E h ν = _h ω = −

atom

２５ stimulated radiation

coherent

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

New emission New emission

-1.2 -0.8 -0.4 0.0 0.4 0.8 1.2

-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4

3400 3500 3600 3700

O u tpu t ( a .u .)

I (/ 100mA)

V (/V)

T = 30 K 2008/4/23

２６

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

2 Δ =60-70 meV

1-2 mv

Another Mechanism Another Mechanism

Cascade Amplification of Stimulated Emission of Radiation Cascade Amplification of Stimulated Emission of Radiation

(CASER) (CASER)

Quasi-particle recombination process occurs near T _c

2 Δ ( Τ )=h ν

２７ h ν

h ν

h ν h ν

Cooper pairs

Quasi-particles

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Estimation of Emission power Estimation of Emission power

obs eff

sample e P

P ≤

4 2

2 2

max

1 . 93 10

) 8 . 0 ( 2 1 ) 635 . 0 (

) 25 (

4 × × = ×

= × π

π e

L=25 cm d =1.27 cm

Si composite Detector Diamond

plate

Sample chopper

optical guide

window d=3.0 cm

mV nW V

S

P

0 . 311

10 73 . 2

200 / 17

5

1

=

= ×

×

=

P _sample ~5 μW

２８

chopper 2 x windows Geometrical factors

Detector sensitivity

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Efficiency of emission Efficiency of emission

２９

at present desired in future

input power 17～20 mW 10-20 mW

output power (at detector) ～5 μW (36.6 nW ) 1 mW

area energy density ～1 W/cm ² ～100 W/cm ²

volume energy density ～300 W/cm ³ ～5x10 ⁴ W/cm ³

efficiency ～3x10 ^-4 ～5-10%

For useful applications, For useful applications, a factor of 100

a factor of 100 - - 200 is necessary! 200 is necessary!

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Comparison of power Comparison of power

mW p

≈ 1

W P ≈ 5 μ

LASER pointer

(class 2)

Green light: 532 nm

IJJ TEASER (STAR-emitter)

at present

x 200 1 mW

efficiency 3 x 10 ^-4 6 x 10 ^-2 =6 %

Coherent, Continuous, and Compact size (Co ³ STAR-emitter)

３０

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Applications (Case I) Applications (Case I)

DNA

finger spectrum

３１

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Case (II) Case (II)

• imaging

３２

After K. Kawase,

Optics and Photonics News, Oct. 2004, p.38

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Case (III) Case (III)

３３

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Case (IV) Case (IV)

Night vision

security

３４

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

N V h

f _obs 2 e ^obs

=

) 029 . 1 ( 1617 673

. 568

791523 .

0 001

. 0

5940 . 483

2 m

f V e N h

obs

obs

= × = = μ

=

1.

2.

ac Josephson effect

3. P _obs ∝ N ²

All junctions are coherent!

N intrinsic junctions work together

as if they are

a big single junction.

(mV) Coherent resonant emission occurs when

w V _obs = 88 . 7 × N

is satisfied. ([w]=[μm])

３５

nw f _obs c

2

= 0 ^{C 0} : velocity of light

n: refractive index =1/ =4.19 w: width of the sample ^ε

Resonance mode with λ = 2 w , w , w / 2 ,...

(～5 μW)

ac Josephson Laser (STAR-emitter)!

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Summary (II) Summary (II)

1. Synchronous Oscillation:

STAR-emitter

Nonlinearlity and nonequilibrium are important!

2. Cascade Amplification of Emission: CASER

direct Cooper pair recombination process near T _c

Two Types of Radiation Mechanisms

３６

4. Monochromatic spectrum

within the limitation of FTIR spectrometer

GHz f ≤ 7 . 5

Δ

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Thank you very much Thank you very much

for your attention!

for your attention!

Summary (III) Summary (III)

There is a room

for increase output power of radiation It needs about 200 times more power

P _out ∼ 1 mW

３７

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Properties of

Properties of IJJ IJJ ’ ’ s s

THz radiation

６ In zero magnetic field,

w ≥ λ J

Short junction:

R(H) oscillation Fraunhofer pattern

Fiske steps MQT

(Macroscopic Quantum Tunneling)

R(H) oscillation No Fraunhofer pattern

No Fiske steps

Collective modes (resonances) (geometrical resonance)

Long junction: w >> λ _J

In zero field, the system behaves as if it is a short junction.

L

w _c

J << ≤ λ ≤ λ

J μ m

λ ≈ ^{0 . 5}

c μ m

λ = 150 − 200

w

L

Mesa Mesa

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Higher Harmonics Higher Harmonics

Note: higher harmonics may contain some background contaminations! １５

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Finite Intensity at

Finite Intensity at θ θ =o _=o ˚ ˚ (I) (I)

Dipole radiation: example

Condmat #08073082, R. Klemm and K. Kadowaki,

“Angular dependence of the radiation power of Josephson STAR-emitter”

２１

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

Finite Intensity at

Finite Intensity at θ θ =o _=o ˚ ˚ (II) (II)

After R. Klemm and K. Kadowaki

２２

JSPS-ESF CTC program N an0-Science and Enginee ring in Superconductivi ty

with other sources with other sources

３０