Spin-dependent transport through a Weyl semimetal surface

Abstract

We experimentally compare two types of interface structures with magnetic and non-magnetic Weyl semimetals. They are the junctions between a gold normal layer and magnetic Weyl semimetal Ti2MnAl, and a ferromagnetic nickel layer and non-magnetic Weyl semimetal WTe2, respectively. Due to the ferromagnetic side of the junction, we investigate spin-polarized transport through the Weyl semimetal surface. For both structures, we demonstrate similar current-voltage characteristics, with hysteresis at low currents and sharp peaks in differential resistance at high ones. Despite this behavior resembles the known current-induced magnetization dynamics in ferromagnetic structures, evolution of the resistance peaks with magnetic field is unusual. We connect the observed effects with current-induced spin dynamics in Weyl topological surface states.

Josephson spin-valve realization in the magnetic nodal-line topological semimetal Fe$_3$GeTe$_2$

“…Spin valve resistance is defined by the relative angle between magnetizations of the layers due to the spin-dependent scattering, which can be tuned by field or flowing current. Spin valve can be naturally realized in different types of topological materials and their heterostuctures with ferromagnets [17][18][19][20] . In this case, spin-polarized topological surface state acts as one layer of a spin valve, while the role of the other is played by the ferromagnetic lead or by the ferromagnetic sample's bulk 17,19 .…”

“…Spin valve can be naturally realized in different types of topological materials and their heterostuctures with ferromagnets [17][18][19][20] . In this case, spin-polarized topological surface state acts as one layer of a spin valve, while the role of the other is played by the ferromagnetic lead or by the ferromagnetic sample's bulk 17,19 . The spin-polarized surface state acts as a source of spin, while spin-dependent scattering within the ferromagnet results in a different resistance depending on the magnetization direction 16 .…”

“…they can be regarded as natural realization of spin-valves. In this case, spin-polarized Fermi arcs and ferromagnetic bulk represent thin (free) and thick (reference) layers, respectively [17][18][19][20] .…”

Magnon modes as a joint effect of surface ferromagnetism and spin-orbite coupling in CoSi chiral topological semimetal

“…Thin flakes can be easily obtained from the initial CoSi single crystal by a regular mechanical cleaving method [34][35][36][37] . We determine the cleaving surface as (001) one from standard magnetoresistance measurements 38 .…”

“…1. This procedure provides 34,35,37 transparent Au-CoSi junctions, stable in different cooling cycles. In addition, green curve shows strictly flat Ohmic dV /dI(I) curve for the reference 2 µm thick CoSi flake.…”