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Gap at the Node in UD LSCO Cuprates

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Gap at the Node in UD LSCO Cuprates. Yu He SC Meeting Jul 11, 2013. Symmetry argument - w hy nontrivial. Doping dependent nodal gap. A temperature perspective – competing orders?. Connection to polaronic settings in UD LSCO. Conflicting experiments and puzzles.

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slide1

Gap at the Node

in UD LSCO Cuprates

Yu He

SC Meeting

Jul 11, 2013

  • Symmetry argument - why nontrivial
  • Doping dependent nodal gap
  • A temperature perspective – competing orders?
  • Connection to polaronic settings in UD LSCO
  • Conflicting experiments and puzzles
slide3

T-dependence on 7% and 10% LSCO

7% LSCO

10% LSCO

TC

Temperature (K)

4 5 6 7 8 9 10 11

Sr doping (%)

TC

slide4

Symmetry argument

d+s wave

Gap size (meV)

Δd fixed at 40meV; line nodes with

Δs = 0, 10, 20, 40, 60meV respectively

AFM fluctuation can give an i-component

Θdeg

d+is wave

Gap size (meV)

W.A. Atkinson et al., PRL 109, 267004 (2012)

Θdeg

slide5

Doping dependent nodal gap

12% LSCO

10% LSCO

antinode

node

Temperature (K)

0 1 2 3 4 5 6 7 8 9 10

Sr doping (%)

1% LSCO

3% LSCO

5% LSCO

7% LSCO

~60meV

~40meV

~20meV

slide6

Conflicting experiments and puzzles

Xingjiang: gap not closing up to 150K in La-Bi2201

Our results: nodal gap not closing up to 200K in 2% LSCO

SLS: nodal gap closes between 80K and 130K in 7% LSCO

Is the competing phase contributing to pairing?

Is the competition unique to LSCO or ubiquitous?

SC on top of Fully gapped FS?

slide7

Conflicting experiments and puzzles

UD22 Bi2212

I.M. Visik et al., PNAS 109, 18332(2012)

slide8

Summary

  • In both non-SC and underdoped-SC regime, gap shows minimum at nodal direction
  • Gap function resembles that from d+is order parameter rather than direct addition of d+s
  • Nodal gap exists in underdoped LSCO when there is no SC
  • Nodal gap coexists with SC below 1/8 doping
  • Beyond 12% Sr-doping, nodal gap vanishes, recovering d-wave SC at node
  • Nodal gap decreases below Tc when Tc is lower than nodal gap’s driving order onset temperature
  • Nodal gap closes at some temperature below Tc when Tcis higher than nodal gap’s driving order onset temperature
slide9

The End.

…and more related background

slide10

Phase diagram in LSCO

Yoichi Ando et al., Phys. Rev. Lett. PRL 93, 267001 (2004)

LSCO: Phase diagram from 2nd derivative of resistivity

AFM

Spin Glass

slide11

ARPES – nodal gap and the struggling history

E. Razzoli. et al., PRL 110, 047004 (2013)

T. Yoshida et al., J. Phys.: Condens. Matter 19 (2007) 125209

Doping dependence

More data: A. Ino et al., PHYSICAL REVIEW B 65, 094504

Inna’s PNAS

slide12

Theory and Computation –

disorder induced broadening and nodal gap

W. Chen et al., PHYSICAL REVIEW B 80, 094519 (2009)

slide13

Neutron – spin fluctuation and correlation length

In LSCO – long range order vs. short range fluctuation

S. Wakimoto et al., PRL 98, 247003 (2007)

M. Matsuda et al., Phys. Rev. B 65, 134515 (2002)

Neutron Scattering Studies of Antiferromagnetic Correlations in Cuprates, J. Tranquada (Chapter 6)

Triangles – commensurate order

Circles – incommensurate order

Spin wave stiffness

Interlayer coupling

slide14

Transport – VRH and NNH

Jun Tateno, PhysicaC 214 (1993) 377-384

slide16

Phase diagram of La-Bi2201

J. Eckstein et al., PRL 96, 107003 (2006)

Y. Ando et al., Phys Rev B 67, 104512 (2003)

Yoichi Ando et al., Phys. Rev. Lett. PRL 93, 267001 (2004)

slide17

Temperature dependence for p=0.55

0.055

With both symmetrization and FD division

12K

Oxygen

0.105

1.05

0.84

p

0.03

0.10

3K

Nodal gap persists up to 300K

No show of data of T>150K b/c ‘disappearance of the coherence peak at high temperatures makes it difficult to quantitatively determine the gap size.’

0.08

0.07

0.055

0.04

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