  The effect of differently oriented magnetic field on chiral incommensurate
helimagnet UPtGe is studied both experimentally and theoretically. The
magnetization measurements up to the field above the saturation have revealed
an isotropic magnetic response below 20 T and a remarkable nonmonotonic
anisotropy in high fields. Moreover, the two principally different phase
transitions from the noncollinear incommensurate to the field-induced
ferromagnetic state have been observed. These properties are successfully
explained by density-functional theory calculations taking into account the
noncollinearity of the magnetic structures, arbitrary directed magnetic field,
and relativistic effects. We also estimate the strength of different competing
magnetic interactions and discuss possible scenarios of the field-induced phase
transformations.
