A rotor includes a shaft; a permanent magnet layer; and a retainer comprising a conductive, low magnetic permeability material bound to the rotor shaft. The permanent magnet layer is semi-restricted between the shaft and the retainer. In one embodiment, the magnet layer includes a molded ring magnet. In another embodiment, the magnet layer includes a plurality of magnet segments which can be situated on the rotor in rotor pockets or in a rotor cage. The bond between the retainer and the rotor can be enabled by a cap or by support elements. A high conductivity material can be situated over the retainer with the combination of the retainer and the high conductivity material having a resistivity high enough to minimize space harmonic losses and low enough to minimize time harmonic losses. The high conductivity material can also be applied to induction rotors for excluding high frequency components while permitting penetration of low frequency torque producing fields.