Single crystals of YBCO: P. Lejay (Grenoble), D. Colson, A. Forget (SPEC)

Electron irradiationLaboratoire des Solides Irradiés

(Ecole Polytechnique)

Disorder, Superconducting fluctuations and Metal-Insulator crossover

in high Tc cuprates

F. Rullier-Albenque1, H. Alloul2, 1 Service de Physique de l’Etat Condensé, CEA, Saclay, France .

2 Physique des Solides, Université Paris-Sud , Orsay, France

F. Balakirev3, C. Proust4

3 NHMFL, Los Alamos National Laboratory, New Mexico, USA4 Laboratoire National des Champs Magnétiques Pulsés, Toulouse, France

500m

Influence of controlled disorder on Tc, T* and the MIC of YBCOZn substitutionElectron irradiation

ConclusionPhase diagram including disorder

Superconducting fluctuations, Nernst effect and magnetoresistance SC fluctuations in « pure » YBCOInfluence of disorder

Disorder, Superconducting fluctuations and Metal-Insulator crossover in high Tc cuprates

IntroductionGeneric phase diagram of the cupratesPresence of incipient disorder?

« Generic » phase diagram of the cuprates?

T*T

Magnetic fluctuations

T c max

Number of holes/ CuO2 plane

PG

AF

SC

underdoped

optimal

overdoped

0 0.1 0.2 0.3

Strange metal

SG

This shape of phase diagram is apparently generic

But only established

in the particular case of La2-xSrxCuO4

x = hole doping

The optimal Tc is not generic

Hole doping not always very well determined

Some questions about High Tc cuprates

T*T

Magnetic fluctuations

T c max

Number of holes/ CuO2 plane

PG

AF

SC

underdoped

optimal

overdoped

0 0.1 0.2 0.3

Strange metal

Pseudogap: Phase transition? Crossover?Link with superconductivity?

Metal-Insulator transition

Importance of magnetic correlations at least for underdoped materials

Transition to a Fermi liquid?

Pseudogap joins Tc

curve or QCP ??

Significant Nernst signal at T>Tc

Signature of superconducting fluctuations in the normal state

Tc = loss of long range phase coherence

La2-x Srx Cu O4

Anomalous Nernst effect in the normal state of cuprates

Effect more pronounced in underdoped samples

Possible implications for the physics of the pseudogap regime: preformed pairs?

Wang et al, PRB 64 (2001)

Tc

Metal – Insulator crossover in low Tc cuprates?

30T

60T

Ono et al, PRL 2000

Metal-Insulator transition

•Induced by the magnetic field•Competition between AF and SC

low Tc cupratesLaSrCuO

La-Bi2201

High magnetic field to suppress superconductivity

Low T upturns in (T)

•Role of intrinsic disorder?

Native disorder in the pure cuprate families

Disorder is detrimental to superconductivitySome uncontrolled disorder is present in LSCO and

Bi2201

Correlation between and optimum Tc

-40.0

-20.0

0.0

20.0

40.0

60.0

80.0

100.0

0 20 40 60 80 100

YBCOBi-2212Tl-2201LSCOLa-Bi2201Bi-2201

R2D

/ (d

R2D

/dT)

Tc (K)

The optimum Tc and the

residual resistivity depend on the family

0

1

2

3

4

5

0 50 100 150 200 250 300

R2

D (k /

)

T (K)

YBCO7

Bi-2201 La-Bi2201

Comparison of the one layer cuprate families

Planar 17O NMR linewidths at optimal doping

YBCO7 20% of Ks

Influence of controlled disorder on Tc, T* and the MICZn substitutionElectron irradiation

ConclusionPhase diagram including disorder

Superconducting fluctuations, Nernst effect and magnetoresistance SC fluctuations in « pure » YBCOInfluence of disorder

Disorder, Superconducting fluctuations and Metal-Insulator crossover in high Tc cuprates

IntroductionGeneric phase diagram of the cupratesPresence of incipient disorder?

Influence of defects on the phase diagram

T*

+ 4%Zn

Tc decreases more rapidly

in underdoped samples

H. Alloul et al, PRL (1991)

Increase of the disordered

magnetism range The position of the optimal Tc shifts with disorder

Phase diagram including disorder

No change of hole doping

No change of T*

Low T electron irradiation

No diffusion of defects

Cryostat coupled to a Hydrogen cryogenerator

Irradiation at 20K

Electron irradiation

Point defects homogeneously distributedElastic collisions between electrons

and target nuclei

Proton irradiation Heavy ion irradiation

Different from :

Cluster of defects , columnar defectsVortex pinning studies

Tc

Influence of irradiation defects on the transport properties

Same single crystals

Excellent control of defect content down to Tc =0

The transition curves remain very sharp Homogeneous damage

0

2

4

6

8

10

0 100 200 300

R2D (

k /

)

(a) Tl-2201

T(K)

Optimally doped overdoped

Matthiessen’s rule well obeyed at high T : )T()T( i0

F. Rullier Albenque et al, Europhysics Letters 50, 81 (2000), PRL (2003)

0

100

200

300

400

500

600

0 50 100 150 200 250 300

.cm

)

T (K)

Tc=25K

Resistivity upturns= MIC?

F. Rullier-Albenque et al , Europhysics Letters (2008).

High field suppresses SC and reveals upturns in irradiated samplesMetallic behavior

in pure YBCO6.6 Upturns related to the presence of defects

55T

0

200

400

600

800

0 50 100 150 200 250 300

.

cm

)

T (K)

0

500

1000

1500

.cm

)

YBCO6.6

pure

A1

B1

C

0

100

200

300

400

500

0 50 100 150 200

.cm

)

T (K)

YBCO7

(b)

pure

A

B

(a)

4%

3%

1.5%

8%

Resistivity upturns = MIC?

)T()T()T( i0

Matthiessen’s rule well obeyed

at high T : )T()T( i0

0

0.5

1

1.5

2

2.5

3

1 10 100

0

T (K)

A

B

C D

Log(1/T) behavior at high enough T

Downward deviations in some cases

0

0.5

1

1.5

2

2.5

3

1 10 100

0

T (K)

A

B

C D

Resistivity upturns vs defect contents in YBCO6.6

0

0.1

0.2

0.3

0.2 0.5 1

(1)(2)(3)

(4)(5)

T / Tdev

B1

A2

1.5 k/2.23.03.84.8

In-situmeasurements

For low defect content : 2D < 5k/scales with 0

Kondo like scattering on defects

saturates at low T

-0.05

-0.04

-0.03

-0.02

-0.01

010 100

(k

-1)

T (K)3

Tl-2201

(a)

(b)

For kFle>>1 (R2D<<26k)

)T

T(Ln

pe

02

2

2

in(T) ~ T p

Rullier-Albenque et al, PRL 87 (2001)

In overdoped samples 2D weak localization effects

induced by disorder

Underdoped YBCO6.6 compared to overdoped Tl2201

OverdopedTl2201

Purely elastic scattering by the defects

Spin glass phase and MIC in the Phase Diagram

SG and MIC are determined by disorder

0

0.5

1

1.5

2

2.5

3

0.01 0.1 1

0

T /Tdev

O6.6

-A1

O6.6

-C(a)

A2

O6.6

-BO

7-B

O6.6

-D

0.01 0.1 1

La0.84

Bi-2201

La0.76

Bi-2201

LaSr0.15

CuO

LaSr0.08

CuO

0

0.5

1

1.5

2

2.5

3

T/Tdev

(b)

Irradiated YBCO compared to « pure» low Tc Cuprates

Controlled disorder Introduced in a pure system

The upturns are quantitatively similarDriven by disorder

Specific disorder reduces Tc

F. Rullier-Albenque et al , Europhysics Letters 81, 37008 (2008).

The various cuprate families in the phase diagram

?

Phase diagram in the absence of disorder

Influence of controlled disorder on Tc, T* and the MICZn substitutionElectron irradiation

ConclusionPhase diagram including disorder

Superconducting fluctuations, Nernst effect and magnetoresistance SC fluctuations in « pure » YBCOInfluence of disorder

Disorder, Superconducting fluctuations and Metal-Insulator crossover in high Tc cuprates

IntroductionGeneric phase diagram of the cupratesPresence of incipient disorder?

-1

0

1

2

3

4

5

0 2 4 6 8

ey (V

/K)

B(T)

35K

45K

55K

58K

Tc = 57K

62K64K

68K70K

85K110K

150K 200K

Nernst effect in pure YBCO6.6

Rapid drop of the Nernst signal at Tc

T onset : 85K

-100

0

100

200

300

80 120 160 200

(n

V/KT

)

T (K)

S tanH

xy/B /B

YBCO6.6

Tc=57K

BS

BT

EH

xy

x

y 1tan

n

xy

s

xyxy

0

200

400

600

800

1000

0

50

100

150

200

60 80 100 120 140

(n

V/K

T)

.cm)

T (K)

Tonset

The temperature range of the Nernst signal increases with decreasing dopingBUT Tonset is higher in optimally doped than in underdoped YBCO

Optimally doped YBCO Underdoped YBCO

Temperature extension of the Nernst signal in pure YBCO

In pure YBCO6.6, the Nernst signal extends up to ~85K much lower that the pseudogap temperature T* ~ 300K

Tonset

0

20

40

60

80

100

-50

0

50

100

150

200

60 80 100 120 140

.cm

)

(nV/KT)

T (K)

0

0.02

0.04

0.06

0.08

0.1

0 500 1000 1500 2000 2500 3000 3500

H2 (T2)

150K

Transverse magnetoresistance under high magnetic fields

130K

2trans0 Ha )/(/

120K

113K

107KH’c

100K97K

2transHa)/(

Harris et al. PRL (1995)Magnetoresistance in the normal state

Transverse magnetoresistivity in YBCO7

High field measurements

10-7

10-6

10-5

0.0001

100 200 300 400 500

atr

ans (

T -

2)

T (K)

Low magnetic fields

High magnetic fields

In YBCO7

Onset of SC fluctuations around 140K

Phase diagram of pure YBCO

How the range of superconducting fluctuations is altered by disorder ?

Onset of fluctuations follows Tc and not T*

0

50

100

150

200

250

300

0 0.05 0.1 0.15 0.2 0.25 0.3

T (

K)

Hole doping

YBCO

'cT

T*

'cT

0

10

20

30

40

50

60

60 80 100 120 140 160

H' c (

T)

T (K)

YBCO7

YBCO6.6

'cTNernst

TcTc

Comparaison YBCO6.6 and YBCO7

0

20

40

60

80

100

120

0 40 80

T (

K)

Tc (K)

YBCO6.6

YBCO7

Tc

T

10 nV/KT

30

In both compounds the T range of the Nernst signal

expands with disorder

Effect more pronounced in underdoped YBCO6.6

F. Rullier-Albenque et al,PRL (2006)

0

200

400

600

800

.cm

)

-100

0

100

0 50 100 150 200

, S

tan

(nV

/KT

)

Stan/B

T (K)

Tc=5K

Tc=30KTc=57K

Tonset is nearly the same for all the samples

Nernst effect in irradiated YBCO

YBCO6.6

Disorder and superconducting fluctuations in YBCO6.6

Magnetoresistance data for the Tc=6K sample

2'c

'c

'c )T/T(1)0(HH

Vortex solid'cT

0

10

20

30

40

50

0 20 40 60 80 100 120

H (

T)

T (K)

vortex liquid+

superconducting fluctuations

normal state

H'c (T)

Tc

F. Rullier-Albenque et al,PRL (2007)

Disorder and superconducting fluctuations in YBCO6.6

2'c

'c

'c )T/T(1)0(H)T(H

With decreasing TcBUT remain quite large

'cT)0(H '

c are depressed and

Tc

0

20

40

60

80

0 40 80 120

H (

T)

T (K)'cT

50

75

100

0 20 40 60

Tc' ,

T (

K)

Tc (K)

Tc'

T

Comparison with Nernst results

systematically higher than T'cT

Wang et al, PRB (2006)

Tc = 28K

Hc2 is nearly unchanged from low T to above Tc

Irradiated YBCO6.6

Tc = 25K

« Pure » underdoped Bi2 Sr2-y Lay Cu O6

y=0.5 - Tc = 28.9K

Wang et al, PRB 64 (2001)

Electron irradiated YBCO6.6

Tc = 24.6K (onset of magnetization)

-20

0

20

40

60

80

100

-2.5

-2

-1.5

-1

-0.5

0

0.5

0 50 100 150

(n

V/K

T)

M (a

rb.u

nits)

T (K)

StanH/B

xy

/B

Tonset ~ 75K

Comparison between La-Bi2201 and irradiated YBCO6.6

Spin glass, MIC , Tc

The different cuprate famlies

Disorder

Low T upturns of resistivityNot necessarily a MIC

Pseudogap and fluctuation regime

Increase of the regime of superconducting fluctuations

Disorder, Superconducting fluctuations and Metal-Insulator crossover in high Tc cuprates