Abrupt onset of a second energy gap at the superconducting transition of underdoped bi2212

ABSTRACT The superconducting gap—an energy scale tied to the superconducting phenomena—opens on the Fermi surface at the superconducting transition temperature (_T_c) in conventional BCS

superconductors. In underdoped high-_T_c superconducting copper oxides, a pseudogap (whose relation to the superconducting gap remains a mystery) develops well above _T_c (refs 1, 2).

Whether the pseudogap is a distinct phenomenon or the incoherent continuation of the superconducting gap above _T_c is one of the central questions in high-_T_c research3,4,5,6,7,8. Although

some experimental evidence suggests that the two gaps are distinct9,10,11,12,13,14,15,16,17,18, this issue is still under intense debate. A crucial piece of evidence to firmly establish

this two-gap picture is still missing: a direct and unambiguous observation of a single-particle gap tied to the superconducting transition as function of temperature. Here we report the

discovery of such an energy gap in underdoped Bi2Sr2CaCu2O8+_δ_ in the momentum space region overlooked in previous measurements. Near the diagonal of Cu–O bond direction (nodal direction),

we found a gap that opens at _T_c and has a canonical (BCS-like) temperature dependence accompanied by the appearance of the so-called Bogoliubov quasi-particles, a classical signature of

superconductivity. This is in sharp contrast to the pseudogap near the Cu–O bond direction (antinodal region) measured in earlier experiments19,20,21. Access through your institution Buy or

subscribe This is a preview of subscription content, access via your institution ACCESS OPTIONS Access through your institution Subscribe to this journal Receive 51 print issues and online

access $199.00 per year only $3.90 per issue Learn more Buy this article * Purchase on SpringerLink * Instant access to full article PDF Buy now Prices may be subject to local taxes which

are calculated during checkout ADDITIONAL ACCESS OPTIONS: * Log in * Learn about institutional subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS

UNCONVENTIONAL SPECTRAL SIGNATURE OF _T_C IN A PURE _D_-WAVE SUPERCONDUCTOR Article 26 January 2022 LOW-ENERGY GAP EMERGING FROM CONFINED NEMATIC STATES IN EXTREMELY UNDERDOPED CUPRATE

SUPERCONDUCTORS Article Open access 26 April 2023 HIDDEN MAGNETIC TEXTURE IN THE PSEUDOGAP PHASE OF HIGH-TC YBA2CU3O6.6 Article Open access 02 November 2022 REFERENCES * Timusk, T. &

Statt, B. The pseudogap in high-temperature superconductors: an experimental survey. _Rep. Prog. Phys._ 62, 61–122 (1999) Article  CAS  ADS  Google Scholar  * Damascelli, A., Hussain, Z.

& Shen, Z. X. Angle-resolved photoemission of cuprate superconductors. _Rev. Mod. Phys._ 75, 473–541 (2003) Article  CAS  ADS  Google Scholar  * Emery, V. J. & Kivelson, S. A.

Importance of phase fluctuations in superconductors with small superfluid density. _Nature_ 374, 434–437 (1995) Article  CAS  ADS  Google Scholar  * Wen, X. G. & Lee, P. A. Theory of

underdoped cuprates. _Phys. Rev. Lett._ 76, 503–506 (1996) Article  CAS  ADS  Google Scholar  * Charkravarty, S., Laughlin, R. B., Dirk, K., Morr, D. K. & Nayak, C. Hidden order in the

cuprates. _Phys. Rev. B_ 63, 094503 (2001) Article  ADS  Google Scholar  * Benfatto, L., Caprara, S. & DiCastro, C. Gap and pseudogap evolution within the charge-ordering scenario for

superconducting cuprates. _Eur. Phys. J. B_ 17, 95–102 (2000) Article  CAS  ADS  Google Scholar  * Li, J.-X., Wu, C.-Q. & Lee, D.-H. Checkerboard charge density wave and pseudogap of

high-_T_ _C_ cuprate. _Phys. Rev. B_ 74, 184515 (2006) Article  ADS  Google Scholar  * Millis, A. J. Gaps and our understanding. _Science_ 314, 1888–1889 (2006) Article  CAS  Google Scholar

  * Opel, M. et al. Carrier relaxation, pseudogap, and superconducting gap in high-_T_ _C_ cuprates: A Raman scattering study. _Phys. Rev. B_ 61, 9752–9774 (2000) Article  CAS  ADS  Google

Scholar  * Le Tacon, M. et al. Two energy scales and two distinct quasiparticle dynamics in the superconducting state of underdoped cuprates. _Nature Phys._ 2, 537–543 (2006) Article  CAS 

ADS  Google Scholar  * Deutscher, G. Coherence and single-particle excitations in the high-temperature superconductors. _Nature_ 397, 410–412 (1999) Article  CAS  ADS  Google Scholar  *

Svistunov, V. M., Tarenkov, V., Yu, D’Yachenko, A. I. & Hatta, E. Temperature dependence of the energy gap in Bi2223 metal oxide superconductor. _JETP Lett._ 71, 289–292 (2000) Article 

CAS  ADS  Google Scholar  * Krasnov, V. M., Yurgens, A., Winkler, D., Delsing, P. & Claeson, T. Evidence of coexistence of the superconducting gap and pseudogap in Bi-2212 from intrinsic

tunnelling spectroscopy. _Phys. Rev. Lett._ 84, 5860–5863 (2000) Article  CAS  ADS  Google Scholar  * Demsar, J., Hudej, R., Karpinski, J., Kabanov, V. V. & Mihailovic, D. Quasiparticle

dynamics and gap structure in HgBa2Ca2Cu3O8+_δ_ investigated with femtosecond spectroscopy. _Phys. Rev. B_ 63, 054519 (2001) Article  ADS  Google Scholar  * Gomes, K. K. et al. Visualizing

pair formation on the atomic scale in the high-_T_ c superconductor Bi2Sr2CaCu2O8+_δ_ . _Nature_ 447, 569–572 (2007) Article  CAS  ADS  Google Scholar  * Boyer, M. C. et al. Imaging the two

gaps of the high-temperature superconductor Bi2Sr2CuO6+_x_ . _Nature Phys._ doi:10.1038/nphys725. (in the press) * Tanaka, K. et al. Distinct Fermi-momentum-dependent energy gaps in deeply

underdoped Bi2212. _Science_ 314, 1910–1913 (2006) Article  CAS  ADS  Google Scholar  * Kondo, T. et al. Evidence for two energy scales in the superconducting state of optimally doped

(Bi,Pb)2(Sr,La)2CuO6+_δ_ . _Phys. Rev. Lett._ 98, 267004 (2007) Article  ADS  Google Scholar  * Loeser, A. G. et al. Excitation gap in the normal state of underdoped Bi2Sr2CaCu2O8+_δ_ .

_Science_ 273, 325–329 (1996) Article  CAS  ADS  Google Scholar  * Norman, M. R. et al. Destruction of the Fermi surface in underdoped high-_Tc_ superconductors. _Nature_ 392, 157–160 (1998)

Article  CAS  ADS  Google Scholar  * Loeser, A. G. et al. Temperature and doping dependence of the Bi–Sr–Ca–Cu–O electronic structure and fluctuation effects. _Phys. Rev. B_ 56, 14185–14189

(1997) Article  CAS  ADS  Google Scholar  * Renner, Revaz, B., Genoud, J.-Y., Kadowaki, K. & Fischer, O. Pseudogap precursor of the superconducting gap in under- and overdoped

Bi2Sr2CaCu2O8+_δ_ . _Phys. Rev. Lett._ 80, 149–152 (1998) Article  CAS  ADS  Google Scholar  * Norman, M. R., Randeria, M., Ding, H. & Campuzano, J. C. Phenomenology of the low-energy

spectral function in high-_T_ _C_ superconductors. _Phys. Rev. B_ 57, R11093–R11096 (1998) Article  CAS  ADS  Google Scholar  * Hosseini, A. Microwave spectroscopy of thermally excited

quasiparticle in YBa2Cu3O6. 99 . _Phys. Rev. B_ 60, 1349–1359 (1999) Article  CAS  ADS  Google Scholar  * Krishana, K., Harris, J. M. & Ong, N. P. Quasiparticle mean free path in

YBa2Cu3O7 measured by the thermal Hall conductivity. _Phys. Rev. Lett._ 75, 3529–3532 (1995) Article  CAS  ADS  Google Scholar  * Valla, T. et al. Fine details of the nodal electronic

excitations in Bi2Sr2CaCu2O8+_δ_ . _Phys. Rev. B_ 73, 184518 (2006) Article  ADS  Google Scholar  * Yamasaki, T. et al. Unmasking the nodal quasiparticle dynamics in cuprate superconductors

using low-energy photoemission. _Phys. Rev. B_ 75, 140513 (2007) Article  ADS  Google Scholar  * Alexandrov, A. S. & Andreev, A. F. Gap and subgap tunneling in cuprates. Preprint at

arXiv:cond-mat/0005315v3 [cond-mat.supr-con] Download references ACKNOWLEDGEMENTS We thank R. Moore for experimental assistance, and D. J. Scalapino, S. Kivelson and T. K. Lee for helpful

discussions. This work is supported by the DOE Office of Basic Energy Science, Division of Materials Science and Engineering, and the National Science Foundation. ARPES experiments were

performed at the Stanford Synchrotron Radiation Laboratory (SSRL), which is operated by the Department of Energy Office of Basic Energy Science. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS *

Department of Physics, Applied Physics, and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94305, USA, W. S. Lee, I. M. Vishik, K. Tanaka, D. H. Lu, T.

Sasagawa & Z.-X. Shen * Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720, USA , K. Tanaka & Z. Hussain * Department of Applied Physics, University

of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan, N. Nagaosa * Department of Physics, University of Waterloo, Ontario N2L 3G1, Canada T. P. Devereaux Authors * W. S. Lee View author publications

You can also search for this author inPubMed Google Scholar * I. M. Vishik View author publications You can also search for this author inPubMed Google Scholar * K. Tanaka View author

publications You can also search for this author inPubMed Google Scholar * D. H. Lu View author publications You can also search for this author inPubMed Google Scholar * T. Sasagawa View

author publications You can also search for this author inPubMed Google Scholar * N. Nagaosa View author publications You can also search for this author inPubMed Google Scholar * T. P.

Devereaux View author publications You can also search for this author inPubMed Google Scholar * Z. Hussain View author publications You can also search for this author inPubMed Google

Scholar * Z.-X. Shen View author publications You can also search for this author inPubMed Google Scholar CORRESPONDING AUTHORS Correspondence to W. S. Lee or Z.-X. Shen. ETHICS DECLARATIONS

COMPETING INTERESTS The authors declare no competing financial interests. SUPPLEMENTARY INFORMATION SUPPLEMENTARY INFORMATION This file contains Supplementary Methods, Supplementary Figures

S1-S3 with Legends and Supplementary Discussion. (PDF 333 kb) RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Lee, W., Vishik, I., Tanaka, K. _et al._

Abrupt onset of a second energy gap at the superconducting transition of underdoped Bi2212. _Nature_ 450, 81–84 (2007). https://doi.org/10.1038/nature06219 Download citation * Received: 28

May 2007 * Accepted: 04 September 2007 * Issue Date: 01 November 2007 * DOI: https://doi.org/10.1038/nature06219 SHARE THIS ARTICLE Anyone you share the following link with will be able to

read this content: Get shareable link Sorry, a shareable link is not currently available for this article. Copy to clipboard Provided by the Springer Nature SharedIt content-sharing

initiative