Penetration Depth Study of LaOs 4Sb 12: Multiband S-Wave Superconductivity


We measured the magnetic penetration depth λ(T) in single crystals of LaOs 4Sb 12 (T c=0.74 K) down to 85 mK using a tunnel-diode-oscillator technique. The observed low-temperature exponential dependence indicates an s-wave gap. Fitting the low-temperature data to a BCS s-wave expression gives the zero-temperature gap value Δ(0)=(1. 34±0.07)k BT c which is significantly smaller than the BCS value of 1.76k BT c. In addition, the normalized superfluid density ρ(T) shows an unusually long suppression near T c and is best fit by a two-band s-wave model. © 2012 American Physical Society.


"This work was supported by the NSF through Grants No. DMR99-72087 and No.DMR01-07253. Some of the work was carried out in the Materials Research Laboratory and Center for Microanalysis of Materials, University of Illinois, which is partially supported by the US Department of Energy under Grant No. DEFG02-91-ER45439. We acknowledge financial support by the National Research Foundation of Singapore. This work was also supported partially by NSFC (Grants No. 10934008, No. 10874215, and No. 11174115) and the MOST 973 Project (No. 2011CB309703) of China, and a Grant-in-Aid for Scientific Research on Innovative Areas “Heavy Electrons” (No. 21102503) of the Ministry of Education, Culture, Sports, Science, and Technology, Japan."


Crystals at low temperatures, Superconductivity


© 2012 American Physical Society