Abstract
Abstract
The superconductor Nb3Sn has important applications for construction of very high-field superconducting magnets. In this work we investigate its microscopic electronic structure with 93Nb nuclear magnetic resonance (NMR). The high-quality Nb3Sn powder sample was studied in both 3.2 T and 7 T magnetic fields in the temperature range from 4 K to 300 K. From measurement of the spectrum and its theoretical analysis, we find evidence for anisotropy despite its cubic crystal structure. Magnetic alignment of the powder grains in the superconducting state was also observed. The Knight shift and spin-lattice relaxation rate,
T
1
−
1
, were measured and the latter compared with BCS theory for the energy gap
Δ
(
0
)
=
2.7
±
0.3
k
B
T
c
at 3.2 T and
Δ
(
0
)
=
2.33
±
0.07
k
B
T
c
at 7 T, indicating suppression of the order parameter by magnetic field.
Funder
National Science Foundation
the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Superconducting Quantum Materials and Systems Center