Inhomogeneous electronic states in superconductors (Chapelier, Ioffe) How to disentangle the...

Inhomogeneous electronic states in superconductors (Chapelier, Ioffe)How to disentangle the unavoidable atomic level inhomogeneity of real materials from the electronic inhomogeneity

discussion-session

Maud VinetWalter EscoffierBenjamin SacépéThomas DubouchetCharlène Tonnoir

Claude ChapelierCEA INAC-SPSMS-LaTEQS, Grenoble

Very Low Temperature STM: a powerful probe for inhomogeneous superconducting states (tutorial)

Very Low Temperature STM: a powerful probe for inhomogeneous superconducting states (tutorial)

I. STM/STS and usual inhomogeneous superconducting states

II. Highly disordered superconductorsIII. Discussion

Coarse approach motor

Coarse positioning X-Y table

Sample holderTipPiezo tube

10

cm

Scanning Tunneling Microscopy

Michael Schmid, TU Wien

P.Mallet et al., J. Vac. Sci. Technol. B 14, 1070 (1996) Michael Schmid, TU Wien

NbSe2

Scanning Tunneling Microscopy

P.Mallet et al., J. Vac. Sci. Technol. B 14, 1070 (1996)

D. Roditchev’s group, http://ln-www.insp.upmc.fr/

Michael Schmid, TU Wien

NbSe2

Scanning Tunneling Microscopy

Scanning Tunneling Spectroscopy

P.Mallet et al., J. Vac. Sci. Technol. B 14, 1070 (1996)

I

V

dI/dV

V

eVfNd

dV

dIVG T

S

)()()(

NbSe2

D. Roditchev’s group, http://ln-www.insp.upmc.fr/

Scanning Tunneling Spectroscopy

P.Mallet et al., J. Vac. Sci. Technol. B 14, 1070 (1996)

I

V

dI/dV

V

eVfNd

dV

dIVG T

S

)()()(

NbSe2

D. Roditchev’s group, http://ln-www.insp.upmc.fr/H. Hess et al., Physica B 169, 422 (1991)

I

V

dI/dV

Scanning Tunneling Spectroscopy

P.Mallet et al., J. Vac. Sci. Technol. B 14, 1070 (1996)

V

eVfNd

dV

dIVG T

S

)()()(

NbSe2

D. Roditchev’s group, http://ln-www.insp.upmc.fr/H. Hess et al., Physica B 169, 422 (1991)

I

V

dI/dV

Scanning Tunneling Spectroscopy

P.Mallet et al., J. Vac. Sci. Technol. B 14, 1070 (1996)

V

eVfNd

dV

dIVG T

S

)()()(

NbSe2

D. Roditchev’s group, http://ln-www.insp.upmc.fr/I. Guillamon et al., Phys. Rev.B 77, 134405 (2008)

http://www.oettinger-physics.de/

Vortex

NbSe2

Sachdev & Zhang, Science

http://www.oettinger-physics.de/

Vortex

H. Hess et al., Phys. Rev. Lett. . 62, 214 (1989)

NbSe2

http://www.oettinger-physics.de/

Vortex

H. Hess et al., Phys. Rev. Lett. . 62, 214 (1989)

NbSe2

http://www.oettinger-physics.de/

Vortex

NbSe2

H. Hess et al., Physica B 169, 422 (1991)

http://www.oettinger-physics.de/

Vortex

H. Hess et al., Physica B 169, 422 (1991)

Ch. Renner et al., Phys. Rev. Lett. (1991)

Nb1-x TaxSe2

http://www.oettinger-physics.de/

Vortex

J.E. Hoffman., Science 295, 466 (2002)

Bi2Sr2CaCu2O8+

Hybrid nanostructures

N. Moussy et al., Europhys. Lett. 55, 861 (2001)

M. Vinet et al., Phys. Rev. B 63, 165420 (2001)

-4 -2 0 2 4

0,5

1,0

1,5

dI/d

V (

no

rmal

ized

)

V [mV]

195 nm

75 nm

12 nm

H. Le Sueur et al., Phys. Rev. Lett. 100, 197002 (2008)

Very Low Temperature STM: a powerful probe for inhomogeneous superconducting states (tutorial)

Superconductor-Insulator Transition

Granular systems Homogeneously disordered materials

H.M. Jaeger, et al., Phys. Rev. B 34, 14920 (1986)

D.B. Haviland, et al., Phys. Rev. Lett. 62, 2180 (1989)

GalliumBismuth

Superconductor-Insulator Transition

TiNReactive sputter deposition of TiN films

Homogeneously disordered ?

N. Hadaceket al., Phys. Rev. B 69, 024505 (2004)

100 nm

10 nm

Superconductor-Insulator Transition

TiN

100 nm

10 nm

T (K)

R (

Ohm

s)

Reactive sputter deposition of TiN films

Granular ?Homogeneously disordered ?

N. Hadaceket al., Phys. Rev. B 69, 024505 (2004)

Superconductor-Insulator Transition

TiN

T (K)

R (

Ohm

s)

Reactive sputter deposition of TiN films

Granular ?Homogeneously disordered ?

N. Hadaceket al., Phys. Rev. B 69, 024505 (2004)

≈ 80 × 80 × 2 nm

≈ 4

00 ×

400

× 3

nmW. Escoffier et al.,Phys. Rev. Lett. 93, 217005 (2004)

100 nm

10 nm

Superconductor-Insulator Transition

TiNReactive sputter deposition of TiN films

Homogeneously disordered ?

N. Hadaceket al., Phys. Rev. B 69, 024505 (2004)

≈ 80 × 80 × 2 nm

≈ 4

00 ×

400

× 3

nmW. Escoffier et al.,Phys. Rev. Lett. 93, 217005 (2004)

100 nm

10 nm

M. Baklanov and A. Satta (IMEC)

Superconductor-Insulator Transition

TiNAtomic layer deposition of 5 nm thick TiN films

-1,0 -0,5 0,0 0,5 1,00,0

0,5

1,0

1,5

2,0

G(V

), n

orm

ali

zed

V [mV]

= 260 µeVT

eff = 0,25 K

-1,0 -0,5 0,0 0,5 1,00,0

0,5

1,0

1,5

2,0

= 225 µeVT

eff = 0,32 K

G(V

), n

orm

ali

zed

V [mV]

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,00

1

2

3

4

5

6

7

8

R [

k]

T [K]

TiN 1 TiN 2 TiN 3

-1,0 -0,5 0,0 0,5 1,00,0

0,5

1,0

1,5

2,0

= 154 µeVT

eff = 0,35 K

G(V

), n

orm

ali

zed

V [mV]

Increasing disorder

Superconductor-Insulator transition

Sacépé et al., Phys. Rev. Lett. 101, 157006 (2008)

TiN

Superconductor-Insulator transition

TiN

λ

Sacépé et al., Phys. Rev. Lett. 101, 157006 (2008)

Tc [K] Δ/TcVar.

[%]

4.7 1.8 ---

1.3 2.3 12

1 2.6 20

0.45 4 50

A. Ghosal, M. Randeria, N. Trivedi, Phys. Rev. Lett. 81, 3940, (1998)Phys. Rev. B 65, 014501 (2001)

M. Ma and P.A. Lee, Phys. Rev. B 32, 5658, (1985)A. Kapitulnik, G. Kotliar, Phys. Rev. Lett. 54, 473, (1985)M. Feigel’man et al., Phys. Rev. Lett. 98, 027001, (2007)M. Feigel’man et al., Ann. Phys. 325, 1390 (2010)M. A. Skvortsov et al., Phys. Rev. Lett. 95,057002, (2005)

Pseudogap

B. Sacépé, et al., Nature Communications 1:140 (2010)

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,00

1

2

3

4

5

6

7

8

R [

k]

T [K]

TiN 1 TiN 2 TiN 3

Superconducting fluctuations correction to the DOS

Short-lived Cooper pairs above Tc

A. Varlamov and V. Dorin, Sov. Phys. JETP 57, 1089, (1983)

Pseudogap

B. Sacépé, et al., Nature Communications 1:140 (2010)

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,00

1

2

3

4

5

6

7

8

R [

k]

T [K]

TiN 1 TiN 2 TiN 3

Superconducting fluctuations correction to the DOS

Short-lived Cooper pairs above Tc

A. Varlamov and V. Dorin, Sov. Phys. JETP 57, 1089, (1983)

Pseudogap

B. Sacépé, et al., Nature Communications 1:140 (2010)

R□

[kΩ]Tc (R□) [K]

Tc (DOS)

[K]

3.5 1.31.3 1.271.27

4.3 1.01.0 0.980.98

7.4 0.450.45 0.450.45

An extreme sensitivity to Tc

Very Low Temperature STM: a powerful probe for inhomogeneous superconducting states (tutorial)

How to disentangle the unavoidable atomic level inhomogeneity of real materials from the electronic inhomogeneity ?

Which inhomogeneities ?

Down to which scale a real material must be considered granular or not ?

What is a homogeneously disordered material ?

How can we relate global macroscopic behavior (transport) and local signatures (STS) ?

Dilution fridge setup

Anomalous proximity effect

Superconducting granular TiN films

-1,5 -1,0 -0,5 0,0 0,5 1,0 1,50,0

0,5

1,0

1,5

2,0

2,5

3,0 x

exp = 0 nm

xcal

= 0 nm x

exp = 12 nm

xcal

= 9 nm x

exp = 20 nm

xcal

= 21 nm x

exp = 32 nm

xcal

= 31 nmdI/d

V

E (meV)

dS,N

W. Escoffier et al., Phys. Rev. Lett. (2004)

≈ 80 × 80 × 2 nm

≈ 4

00 ×

400

× 3

nm

Theory : Zhang & Xiong,

Physica C (2006)

Anomalous proximity effect

Superconducting granular TiN films

B. Sacépé (unpublished)

1500 nm x 1500 nm

Superconducting fluctuations quantum corrections

Tc [K]

1.3

1

0.45

One parameter fit : Tc

Superconducting fluctuations quantum corrections