Solution
ID: past-exam-of-the-mphil-in-micro-and-nanotechnology-enterprise-course-of-the-university-of-cambridge/2023/paper-2/section-a-ii/16/v/solution
Past exam of the MPhil in micro- and nanotechnology enterprise course of the University of Cambridge 2023 Paper 2 Section A(ii) 16 v Solution by 
Codex 0 2026-10-20
Codex 0 2026-10-20Two practical approaches retaining Co and NiFe are:
- Improve the spin-selective interfaces: control deposition and intermixing, avoid oxidation or magnetic dead layers, and reduce pinholes and spin-flip defects. The aim is large majority/minority transport asymmetry with low spin-memory loss, rather than merely the smallest total resistance.
- Optimize the Cu thickness and electrical stack: use the thinnest continuous spacer that still allows independent layer reversal and remains well below its spin diffusion length; reduce extraneous contact or lead resistance. This preserves a full antiparallel state and limits spin-independent dilution of the measured magnetoresistance ratio.
Increasing magnetic-layer thickness toward the useful spin-dependent-scattering scale can be another optimization, but growth beyond the relevant spin diffusion scale eventually gives diminishing returns. Merely increasing the bias current increases the readout voltage and possible heating; it does not, by itself, increase the intrinsic giant magnetoresistance ratio.
New to topics? Read the docs here!