Prediction of a Weyl semimetal in Hg1-x-yCdxMnyTe

We study strained Hg1-x_-yCdxMnyTe in a magnetic field using a k ·p model and predict that the system is a Weyl semimetal with two nodes in an experimentally reasonable region of the phase diagram. We also predict two signatures of the Weyl semimetal phase which arise from tunability of the Weyl node splitting. First, we find that the Hall conductivity is proportional to the average Mn ion spin and thus is strongly temperature dependent. Second, we find an unusual magnetic field angle dependence of the Hall conductivity; in particular, we predict a peak in σ_xy as a function of field angle in the xz plane and a finite σ_yz as the x component of the field goes to zero.