Electronic structure investigation of the exchange-spring behavior during the magnetic reversal process

We present an atomic scale quantum-mechanical theory based on a noncollinear tight-binding formalism for self-consistent calculations of electronic and magnetic structures of d-metallic systems in an external magnetic field. The theory is applied to the description of the magnetic reversal process in exchange-spring magnets with Fe as the soft magnetic material. From the magnetic spin configuration obtained through the electronic structure calculation in different external fields, we have determined the average magnetic moment and the reversible part of the hysteresis loop. The calculations reproduce all the main features of the exchange-spring behavior. The theory is suitable for the study of more complex systems with interface roughness, interdifussion, and noncoplanar magnetic ordering.