Abstract
Using the small angle neutron scattering (SANS) technique we investigated the vortex lattice (VL) in the mixed state of the stannide superconductor . We find a single domain VL of slightly distorted hexagonal geometry for field strengths between 350 and 18 500 G and temperatures between and 6.5 K. We observe a clear in-plane rotation of the VL for different magnetic field directions relative to the crystallographic axes. We also find that the hexagonal symmetry of the VL is energetically favorable in for external fields oriented along axes of different symmetries: twofold [110], threefold [111], and fourfold [100]. The observed behavior is different from other conventional and unconventional superconductors. The superconducting state is characterized by an isotropically gapped order parameter with an amplitude of meV. At the lowest temperatures, the field dependence of the magnetic form factor in our material reveals a London penetration depth of Å and a Ginzburg coherence length of Å, i.e., it is a strongly type-II superconductor, .
- Received 29 May 2014
- Revised 24 June 2014
DOI:https://doi.org/10.1103/PhysRevB.90.020507
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