We have investigated a gap structure in a newly discovered superconductor, MgB2, through measurement of the 11B nuclear spin-lattice relaxation rate, 11(1/T1). 11(1/T1) is proportional to the temperature (T) in the normal state, and decreases exponentially in the superconducting (SC) state, revealing a tiny coherence peak just below Tc. The T dependence of 1/T1 in the SC state can be accounted for by an s-wave SC model with a large gap size of 2Δ/kBTc∼5 which suggests it is in a strong-coupling regime.
ASJC Scopus subject areas
- Physics and Astronomy(all)