The Depairing Current Density of a Fe(Se,Te) Crystal Evaluated in Presence of Demagnetizing Factors

Authors: Armando Galluzzi, Krastyo Buchkov, Vihren Tomov, Elena Nazarova, Antonio Leo, Gaia Grimaldi, Adrian Crisan and Massimiliano Polichetti 

Condens. Matter 2023, 8(4), 91

Abstract: The effect of the demagnetizing factor, regarding the determination of the de-pairing current
density Jdep, has been studied in the case of a Fe(Se,Te) crystal, using DC magnetic measurements
as a function of a magnetic field (H) at different temperatures (T). First, the lower critical field
Hc1(T) values were obtained, and the demagnetization effects acting on them were investigated after
calculating the demagnetizing factor. The temperature behaviors of both the original Hc1 values
and the ones obtained after considering the demagnetization effects (Hdemag c1) were analyzed, and
the temperature dependence of the London penetration depth λL(T) was obtained in both cases. In
particular, the λL(T) curves were fitted with a power law dependence, indicating the presence of
low-energy quasiparticle excitations. Furthermore, by plotting λ−2L as a function of T, we found that
our sample behaves as a multigap superconductor, which is similar to other Fe-11 family iron-based
compounds. After that, the coherence length ξ values were extracted, starting with the Hc2(T) curve.
The knowledge of λL and ξ allowed us to determine the Jdep values and to observe how they are
influenced by the demagnetizing factor