Quadratic to linear magnetoresistance tuning in TmB4:
We observed large, positive and anisotropic magnetoresistance (MR) in single crystals of the antiferromagnetic metal, TmB4. MR can be tuned from quadratic to linear by changing the direction of the applied field. We attribute our observations to the anisotropic Fermi surface topology of TmB4. Notably, the linear MR is found to be temperature independent, suggestive of quantum mechanical origin.