title: Double resonance mechanism of ferromagnetism and magnetotransport in (Ga-Mn)As
abstract: We calculate the electronic states of the Mn-doped semiconductors and show that resonant states are formed at the top of the down spin valence band due to magnetic impurities and that they give rise to a strong and long-ranged ferromagnetic coupling between Mn moments. We propose that the coupling of the resonant states, in addition to the intra-atomic exchange interaction between the resonant and nonbonding states, is the origin of the ferromagnetism of (Ga-Mn)As. The mechanism is thus called "double resonance." The resonant states bring about the spin-dependent resistivity to produce magnetoresistive properties in (Ga-Mn)As and their junctions.
authors.affiliation: Department of Applied Physics, Nagoya University, Nagoya 464-8603, Japan and and CREST, Japan Science and Technology Corporation (JST), Japan.
authors.initials: J
authors.lastname: Inoue
authors.initials: S
authors.lastname: Nonoyama
authors.initials: H
authors.lastname: Itoh