Such a Motors designs more efficient than an induction motor but less efficient than an permanent magnet brushless motor. However, it is less expensive than a permanent magnet brushless motor since there are no magnets in the rotor. Each motor has to be very precisely designed for the specific application. These motors also have teeth in the rotor and stator. The teeth line up so that the motor shaft goes through distinct preferred positions each separated by the motors step angle which is determined by the design of the motor.
Stepper motors are cheap, simple and perfect for positioning applications run by computers.
Stepper motors however are not very efficient and they are not suitable for high speed applications .