  This paper considers certain materials, including topological insulators,
where spin rotation symmetry is broken much more strongly than time reversal
symmetry. When these materials are in the diffusive regime, i.e. when they have
disorder that is strong enough to cause an electron to scatter many times while
crossing a sample, electrons and holes move in pairs that have zero spin and
are insensitive to spin physics. Working within this spinless scenario, we show
that Fourier transforming the magnetoconductance with respect to external
magnetic field obtains a curve describing the area distribution of loops traced
by electrons and holes within the sample. We present loop area distributions of
Landau levels, weak (anti)localization, conduction governed by Levy flights,
and linear-in-field resistance. Of these four the last two are new results.
Comparing these distributions, we argue that the linear-in-field resistance
seen in some topological insulators is caused by the same diffusive scattering
that causes weak antilocalization. The difference is that linear-in-field
resistance materials retain a level of quantum coherence that is usually seen
only on the surface of 2-D wires or in ring geometries. In an appendix we
include some speculative material about linear-in-temperature resistance.
