Angular variation of the magnetoresistance of the superconducting ferromagnet UCoGe

We report a magnetoresistance study of the superconducting ferromagnet UCoGe. The data, taken on single-crystalline samples, show a pronounced structure at B*=8.5 T for a field applied along the ordered moment m0. Angle-dependent measurements reveal that this field-induced phenomenon has an uniaxial anisotropy. Magnetoresistance measurements under pressure show a rapid increase of B* to 12.8 T at 1.0 GPa. We discuss B* in terms of a field-induced polarization change. Upper critical field measurements corroborate the unusual S-shaped Bc2(T) curve for a field along the b axis of the orthorhombic unit cell.