Magnetotransport study of nanoscale Permalloy–Si tunnelling structures in lateral spin-valve geometry

Abstract

Magnetotransport measurements were performed on a Permalloy/Mg/SiO 2 /n + -Si (100) spin-valve tunnelling device. Magnetic force microscope imaging proves the single-domain state of the 1 µm elongated and 200 nm wide parallel Permalloy (Py) electrodes. Anisotropic magnetoresistance (AMR) measurements reveal precisely the magnetic field interval of antiparallel magnetization configuration essential for spin-valve operation, in between the switching fields of 15 and 40 mT. Unlike the negative AMR of the Py wires, the tunnelling device shows a small positive magnetoresistance for antiparallel magnetization configuration, as expected for the spin-blockade mechanism.

Subsurface enrichment of Co in Si (100) at initial stages of growth at room temperature: A study by high-resolution Rutherford backscattering

“…1 In such a Co-Si heterostructure any structural disorder at the interface would drastically reduce the spin polarization, and hence the spin injection efficiency. [2][3][4] The phenomena observed at the initial stages of Co deposition on a Si substrate seem to be unique and depend on the preparation conditions. 5-10 About the growth mode of Co on Si, Cho et al 5 concluded that the Co atoms grow in a layer-by-layer mode, without any interdiffusion, whereas Meyerheim et al 6 and Rangelov et al 7 could see the in-diffusion of Co atoms for coverages higher than 0.5 ML of Co. About the atomic positions of Co atoms on Si ͑100͒, Scheuch et al, 8 Meyerheim et al, 6 and Gomoyunova et al 9 found that Co is adsorbed in fourfold hollow sites ͑nearly in plane, d Ќ Ϸ 0͒ in every second ͓110͔ row of the Si ͑100͒ surface.…”

Wideband and On-Chip Excitation for Dynamical Spin Injection into Graphene

“…1 (b) for a false-colour electron micrograph of a sample at this fabrication stage. A thin Py layer together with the negligible crystal anisotropy of Py favours a homogeneous in-plane magnetization aligned with the external magnetic field H 31,32 . The length of the spin transport channel L is defined by the Py and the Pt electrode separation.…”

Introduction to spin-polarized ballistic hot electron injection and detection in silicon

“…Owing to its apparent advantages over other semiconductors, many groups tried to demonstrate phenomena attributed to spin transport in Si [31][32][33][34][35][36][37][38][39], but this was typically done with ohmic FM-Si contacts and two-terminal magnetoresistance measurements or in transistor-type devices [40,41], which are bound to fail owing to the 'fundamental obstacle' for ohmic spin injection mentioned in §1 [1][2][3][4]. Although weak spin-valve effects are often presented, no evidence of spin precession is available so the signals measured are ambiguous at best [42,43].…”