An electric machine having a rotor is disclosed. The rotor defines a cavity containing a magnet, an outer periphery, and a top bridge therebetween that includes at least two slots each having a length in a radial direction. A maximum of the lengths is closest to a Q-axis and a minimum of the lengths is closest to a D-axis. As the electric machine is operating, a rate of change in airgap flux density through the top bridge differs.