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Title: Strong interaction between electrons and collective excitations in the multiband superconductor MgB 2

We use a tunable laser angle-resolved photoemission spectroscopy to study the electronic properties of the prototypical multiband BCS superconductor MgB 2. Our data reveal a strong renormalization of the dispersion (kink) at ~65meV, which is caused by the coupling of electrons to the E 2g phonon mode. In contrast to cuprates, the 65 meV kink in MgB 2 does not change significantly across T c. More interestingly, we observe strong coupling to a second, lower energy collective mode at a binding energy of 10 meV. As a result, this excitation vanishes above T c and is likely a signature of the elusive Leggett mode.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [2] ;  [1]
  1. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
OSTI Identifier:
1227294
Report Number(s):
IS-J-8612
Journal ID: ISSN 1098-0121; PRBMDO
Grant/Contract Number:
AC02-07CH11358; AC02-98CH10886
Type:
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 91; Journal Issue: 14; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY