Extending Universal Nodal Excitations Optimizes Superconductivity in Bi2Sr2CaCu2O8+{delta}

doi:10.1126/science.1174338

Science/AAAS

Advanced

Guest Alerts | Access Rights | My Account | Sign In

Article Views

VERSION HISTORY

324/5935/1689 (most recent)
1174338v1

Article Tools

My Science

Published Online June 4, 2009
Science DOI: 10.1126/science.1174338

Science Express Index

Reports

Submitted on March 31, 2009
Accepted on May 21, 2009

Extending Universal Nodal Excitations Optimizes Superconductivity in Bi₂Sr₂CaCu₂O₈₊

Aakash Pushp ¹, Colin V. Parker ², Abhay N. Pasupathy ³, Kenjiro K. Gomes ⁴, Shimpei Ono ⁵, Jinsheng Wen ⁶, Zhijun Xu ⁶, Genda Gu ⁶, Ali Yazdani ²^*

¹ Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544, USA.; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
² Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544, USA.
³ Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544, USA.; Present address: Department of Physics, Columbia University, New York, NY 10027, USA.
⁴ Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544, USA.; Present address: Department of Physics, Stanford University, Stanford, CA 94305, USA.
⁵ Central Research Institute of Electric Power Industry, Komae, Tokyo 201-8511, Japan.
⁶ Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973, USA.

^* To whom correspondence should be addressed.
Ali Yazdani , E-mail: yazdani{at}princeton.edu

These authors contributed equally to this work.

Understanding the mechanism by which d-wave superconductivityin the cuprates emerges and is optimized by doping the Mottinsulator is one of the major outstanding problems in condensedmatter physics. Our high-resolution scanning tunneling microscopymeasurements of the high transition temperature (T_c) superconductorBi₂Sr₂CaCu₂O₈₊ show that samples with different T_cs in the lowdoping regime follow a remarkably universal d-wave low energyexcitation spectrum, indicating a doping independent nodal gap.We demonstrate that T_c instead correlates with the fractionof the Fermi surface over which the samples exhibit the universalspectrum. Optimal T_c is achieved when all parts of the Fermisurface follow this universal behavior. Increasing temperatureabove T_c turns the universal spectrum into an arc of gaplessexcitations, while overdoping breaks down the universal nodalbehavior.