An epitaxial Ni.sub.3FeN film with unique magnetic properties such as single magnetic domain (even in a large scale 0.5''.times.0.5''), which rotates coherently in response to the desired switching field with a very sharp transition is described. The magnetic hysteresis loop of this new magnetic nitride is close to the perfect ideal square with the same value of saturation magnetization, remnant magnetization, and magnetization right before switching (domain reversal). The switching field is tunable which make this material more attractive for magneto-resistive devices such as MRAM's, read heads and magnetic sensors.