Probing the anisotropic vortex lattice in the Fe-based superconductor KFe2As2 using small angle neutron scattering

Journal Article · Tue Jan 01 00:00:00 EST 2013 · Physical Review B

OSTI ID:1147691

Debeer-Schmitt, Lisa M ^[1]; Dewhurst, Charles ^[2]; Kikuchi, Hiroko ^[3]; Cameron, Alistair ^[4]; Heslop, Richard ^[4]; Forgan, E. M. ^[4]; Bowell, Charlotte ^[5]; White, Jonathon ^[6]; Gavilano, Jorge ^[7]

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1. ORNL
2. Institut Laue-Langevin (ILL)
3. Ochanomizu University, Japan
4. University of Birmingham, The, Birmingham, United Kingdom
5. University of Cambridge
6. Laboratory for Neutron Scattering ETHZ & PSI
7. ETH Zurich, Switzerland

Using small angle neutron scattering, the anisotropy of the magnetic vortex lattice (VL), in the heavily hole-doped pnictide superconductor, KFe2As2, was studied. Well-ordered VL scattering patterns were measured with elds applied in directions between B k c and the basal plane, rotating either towards [100] or [110]. Slightly distorted hexagonal patterns were observed when B k c. However, the scattering pattern distorted strongly as the eld was rotated away from the c- axis. At low eld, the arrangement of vortices is strongly aected by the anisotropy of penetration depth in the plane perpendicular to the eld. By tting the distortion with the anisotropic London model, we obtained an estimate of 3:4 for the anisotropy factor, , between the in-plane and c-axis penetration depths at the lowest temperature studied. The results further reveal VL phase transitions as a function of eld direction. We discuss these transitions using the "Hairy Ball" theorem.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1147691
• Journal Information: Physical Review B, Vol. 88, Issue 13
• Country of Publication: United States
• Language: English