Gap at the Node in UD LSCO Cuprates

Yu HeSC MeetingJul 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

30meV

T-dep nodal gap in 2% LSCO

T-dependence on 7% and 10% LSCO

10% LSCO

4 5 6 7 8 9 10 11Sr doping (%)

Tem

pera

ture

(K)

7% LSCO

TCTC

Symmetry argumentd+s wave

Θ deg

Gap size (meV)d+is wave

Gap size (meV)

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

Θ deg

Δd fixed at 40meV; line nodes with Δs = 0, 10, 20, 40, 60meV respectively

AFM fluctuation can give an i-component

Doping dependent nodal gap

1% LSCO 3% LSCO 5% LSCO 7% LSCO

node

antinode10% LSCO 12% LSCO

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

SC on top of Fully gapped FS?

Is the competing phase contributing to pairing?Is the competition unique to LSCO or ubiquitous?

Conflicting experiments and puzzles

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

UD22 Bi2212

• 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 Tc is higher than nodal gap’s driving order onset temperature

• 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

Summary

The End. …and more related background

Phase diagram in LSCOYoichi Ando et al., Phys. Rev. Lett. PRL 93, 267001 (2004)

E. Razzoli. et al., PRL 110, 047004 (2013)ARPES – nodal gap and the struggling history

Inna’s PNAS

Doping dependence

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

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

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

Theory and Computation – disorder induced broadening and nodal gap

Neutron – spin fluctuation and correlation length

In LSCO – long range order vs. short range fluctuationS. 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)

Interlayer coupling

Spin wave stiffness

Triangles – commensurate order

Circles – incommensurate order

Transport – VRH and NNHJun Tateno, Physica C 214 (1993) 377-384

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

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

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

Phase diagram of La-Bi2201

p1.05 0.840.03 0.10

0.040.055

0.070.08

0.105

3K12K Oxygen

1. Nodal gap persists up to 300K2. 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.’

With both symmetrization and FD division

0.055

Temperature dependence for p=0.55