Two-component systems with equal concentrations of electrons and holes
exhibit non-saturating, linear magnetoresistance in classically strong magnetic
fields. The effect is predicted to occur in finite-size samples at charge
neutrality in both disorder- and interaction-dominated regimes. The phenomenon
originates in the excess quasiparticle density developing near the edges of the
sample due to the compensated Hall effect. The size of the boundary region is
of the order of the electron-hole recombination length that is inversely
proportional to the magnetic field. In narrow samples and at strong enough
magnetic fields, the boundary region dominates over the bulk leading to linear
magnetoresistance. Our results are relevant for semimetals and narrow-band
semiconductors including most of the topological insulators.Comment: 11 pages, 3 figure