Giant planar Hall effect in an ultra-pure mercury selenide single crystal sample

A giant planar Hall effect with an amplitude of about $50$ m$\Omega$ cm at a temperature of $T = 80$ K in a magnetic field of $10$ T has been detected in an ultra-pure HgSe single crystal sample with an electron density of $5.5\times 10^{15}$ cm$^{-3}$. Its oscillating dependence on the rotation angle of the sample in various magnetic fields has been determined. Attributes (oscillation period, positions of extrema, correlation between the amplitudes of planar Hall and planar longitudinal magnetoresistance) indicate that the planar Hall effect in this nonmagnetic gapless semimetal with an isotropic Fermi surface originates from the chiral anomaly. This is a solid argument for the topological nature of the electronic spectrum of HgSe.