= Solution
Sweep the in-plane <magnetic field> approximately along the wires' easy axes. At large negative field, both <magnetizations> are parallel. If the wires reverse at different positive coercive fields, an antiparallel interval separates this state from the final parallel positive-field state. In the usual positive <giant magnetoresistance> case, \b[the antiparallel interval has higher resistance]; the reverse sweep gives a mirrored interval and a <hysteresis> loop.
An ideal angular model is
$$
R(\phi)=R_P+\frac{\Delta R}{2}(1-\cos\phi),\qquad \Delta R=R_{AP}-R_P>0.
$$
Spin-dependent injection and scattering favor transmission through similarly aligned electrodes. The <two-current resistor model> represents this using unequal majority- and minority-spin resistances. Both layers can reverse, hence <pseudo spin valve>, rather than an absolutely pinned reference layer.
The different thicknesses can produce different switching properties, but \b[thickness alone does not identify which electrode reverses first]. Measure their coercive fields. The local resistance also contains Cu, contact and Py <anisotropic magnetoresistance> contributions. Rotation scans and individual-wire controls distinguish them. Py/Cu experiments showed that local contact-related signals can exceed the spin-valve contribution, motivating nonlocal detection.<Spin injection and spin accumulation in all-metal mesoscopic spin valves by F. J. Jedema and others>[2003, abstract and local/nonlocal measurement comparison]{ref}
\Image[/past-exam-of-the-mphil-in-micro-and-nanotechnology-enterprise-course-of-the-university-of-cambridge/2020/paper-2-spin-and-wetting.png]
{title=Ideal spin-valve switching and surface-energy balances for wetting}
{description=Original chosen switching curves, force diagram and composite-wetting curve. Switching fields and signal heights are illustrative rather than measured.}
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