Kamashev Andrey A, Validov Aidar A, Schumann Joachim, Kataev Vladislav, Büchner Bernd, Fominov Yakov V, Garifullin Ilgiz A
Zavoisky Physical-Technical Institute, Russian Academy of Sciences, 420029 Kazan, Russia.
Leibniz Institute for Solid State and Materials Research IFW Dresden, D-01171 Dresden, Germany.
Beilstein J Nanotechnol. 2018 Jun 12;9:1764-1769. doi: 10.3762/bjnano.9.167. eCollection 2018.
We have studied superconducting properties of spin-valve thin-layer heterostructures CoO /F1/Cu/F2/Cu/Pb in which the ferromagnetic F1 layer was made of Permalloy while for the F2 layer we have taken a specially prepared film of the Heusler alloy CoCr Fe Al with a small degree of spin polarization of the conduction band. The heterostructures demonstrate a significant superconducting spin-valve effect, i.e., a complete switching on and off of the superconducting current flowing through the system by manipulating the mutual orientations of the magnetization of the F1 and F2 layers. The magnitude of the effect is doubled in comparison with the previously studied analogous multilayers with the F2 layer made of the strong ferromagnet Fe. Theoretical analysis shows that a drastic enhancement of the switching effect is due to a smaller exchange field in the heterostructure coming from the Heusler film as compared to Fe. This enables to approach an almost ideal theoretical magnitude of the switching in the Heusler-based multilayer with a F2 layer thickness of ca. 1 nm.
我们研究了自旋阀薄层异质结构CoO /F1/Cu/F2/Cu/Pb的超导特性，其中铁磁F1层由坡莫合金制成，而F2层则采用了专门制备的具有小导带自旋极化程度的赫斯勒合金CoCrFeAl薄膜。这些异质结构展现出显著的超导自旋阀效应，即通过操控F1和F2层磁化的相互取向，使流经该系统的超导电流完全开启和关闭。与之前研究的由强铁磁体Fe制成F2层的类似多层结构相比，该效应的幅度翻倍。理论分析表明，开关效应的大幅增强是由于与Fe相比，来自赫斯勒薄膜的异质结构中的交换场较小。这使得在F2层厚度约为1nm的基于赫斯勒合金的多层结构中，能够接近几乎理想的理论开关幅度。
