Muon spin relaxation (
SR) studies have been performed in the normal spinel LiTi
2O
4 and the A-15 superconductor V
3Si to measure the magnetic penetration depth . The relaxation rate
(T) 1/
2 in field-cooled measurements shows a sharp increase below
T
c
followed by saturation at low temperatures in both systems. This feature implies an isotropic energy gap without anomalous zeros, and most likely
s-wave pairing. The low temperature penetration depth (
T 0) is determined to be 2100Å for LiTi
2O
4 and 1300Å for V
3Si respectively. Assuming a clean limit relation
–2 n
s
/
m
*, we derive the Fermi temperature
T
F
n
s/
2/3
m
* from the relaxation rate
and the Sommerfeld constant
as
T
F
3/4–1/4. Unlike conventional superconductors, both LiTi
2O
4 and V
3Si have a large ratio of
T
c
/
T
F
0.01, only slightly smaller than those ratios in more exotic superconductors.We thank C. Ballard and K. Hoyle for technical assistance. Work at Columbia University is supported by NSF Grant No. DMR-89-13784 and Packard Foundation (YJU). Ames Laboratory is operated for the U. S. Department of Energy by Iowa State University under Contract No. W-7405-Eng-82. Work at Ames was supported by the Director for Energy Research, Office of Basic Energy Sciences.
相似文献