title: Low-temperature anomalies in resistance and magnetoresistance of amorphous FeCrB ribbons. Coexistence of ferromagnetism and local superconductivity?
abstract: Investigation of the conductivity mechanisms in ferromagnetic Fe(67)Cr(18)B(15) metallic glasses with clusterized structure reveals anomalies in the behaviour of resistance and magnetoresistance (MR) in a narrow temperature interval, T = 3.6-3.1 K. The anomalies are seen as a sharp decrease of the sample resistivity in this range, with a rate equal to 3.6% K(-1), i.e. 200-500 times more than the rate 0.008-0.021% K(-1) in the range of 300-4 K. MR in the same range increases with a rate 1000 times larger (4% K(-1) at T ∼ 3.1-3.6 K) than in the 300-4 K range (<0.0015% K(-1)). We explain this result by the appearance of local superconductivity in the large-scale layered clusters of metallic Fe-Cr phase, 150-200 Å in size, with ferromagnetic Fe(2)Cr core and nonmagnetic FeCr(2) superconducting shell. The superconducting phase, which occupies 0.4-0.5% of the sample volume, provides a resistance jump Δρ/ρ≈1.5% that corresponds to calculation. The superconducting state of the clusters collapses if the magnetic field exceeds 20 kOe.
authors.affiliation: Donetsk Physiko-Technical Institute, Ukrainian National Academy of Sciences, Donetsk, Ukraine. okunev@mail.fti.ac.donetsk.ua
authors.forename: V D
authors.initials: VD
authors.lastname: Okunev
authors.forename: Z A
authors.initials: ZA
authors.lastname: Samoilenko
authors.forename: A
authors.initials: A
authors.lastname: Szewczyk
authors.forename: R
authors.initials: R
authors.lastname: Szymczak
authors.forename: H
authors.initials: H
authors.lastname: Szymczak
authors.forename: P
authors.initials: P
authors.lastname: Aleshkevych
authors.forename: J
authors.initials: J
authors.lastname: Wieckowski
authors.forename: V S
authors.initials: VS
authors.lastname: Khmelevskaya
authors.forename: I A
authors.initials: IA
authors.lastname: Antoshina