Flux-flow Hall effect measurement of FeSe pure single crystals

Previous measurements of the effective viscous drag coefficient of the moving vortex show that, contrary to expectations, the vortex core is moderately clean in various clean superconductors [1], which has not been understood by existing theories. Therefore, we evaluated the quasiparticle electronic state in the core by an alternative technique of measuring the microwave flux-flow Hall effect using a newly developed method [2]. We performed the vortex Hall angle measurements of another candidate of clean superconductors, FeSe prepared by vapor transport method [3] to see how large the flux-flow Hall angle would be.  As a result, the tangent of the Hall angle of FeSe is about 0.5, which is slightly smaller than those obtained by the conventional method [4].  Furthermore, the flux-flow Hall angle shows a non-monotonic magnetic field dependence. These are likely to be due to the cancellation of the hole and electron contributions, which is characteristic of multiband superconductors.

[1] Y. Tsuchiya et al., PRB 63, 184517 (2001). [2] R. Ogawa, et al., J. Appl. Phys. 129, 015102 (2021).  [3] A. E. Böhmer et al., Phys. Rev. B 87, 180505 (2013) [4] T. Okada, et al., JPSJ 90, 094704 (2021).