Nitrides as spintronic materials

Abstract

A report on the progress in spintronics‐related works involving group III nitrides is given, emphasizing contradictory opinions concerning the basic characteristics of these materials. The actual position of magnetic impurities in the GaN lattice as well as a possible role of magnetic precipitates is discussed. The question as to whether the hole introduced by Mn impurities is localized tightly on the Mn d levels or rather on the hybridized p–d bonding states is addressed. The nature of spin–spin interactions and magnetic phases, as provided by theoretical and experimental findings, is outlined and the possible origins of the high‐temperature ferromagnetism observed in (Ga, Mn)N are presented. Experimental studies aimed at evaluating characteristic times of spin coherence and dephasing in GaN are described. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Fe in III–V and II–VI semiconductors

“…This splitting has only been resolved in hexagonal ZnO and GaN [12,25]. Polarized measurements suggest that in GaN the top states 7 Γ and 8 Γ swap their energetic positions [12].…”

“…Until today, the correct energetic order of the 7 Γ and 8 Γ states has been unknown. In Section 4.3.3 we present CAS data indicating that, in GaP and InP, the 8 Γ level is above the 7 Γ level.…”

“…T symmetry is only split by spin-spin and second order spin-orbit interaction into two states of 7 Γ and 8 Γ symmetry. Until today, the correct energetic order of the 7 Γ and 8 Γ states has been unknown.…”

Transition from ferromagnetism to antiferromagnetism in Ga1−xMnxN

“…Other groups argue that no secondary phase is observed in their single-crystal GaMnN samples that show ferromagnetism [9]. There are also discussions about whether the relevant Mn 3d state has d 4 or d 5 + h character, or whether the d levels are localized in the bandgap or inside the valence band [10].Although many of the issues are still under intensive study, recent ab initio band structure and total energy calculations [11,12,13] seem to agree that Mn 3d levels are located in the gap, and that the interaction between substitutional Mn ions is ferromagnetic (FM) at low Mn concentration. Because previous ab initio studies also find that pure MnN has an AFM ground state [14], an interesting question was raised about how the magnetic and electronic properties of Ga 1−x Mn x N evolve as a function of the Mn concentration x.…”

“…Other groups argue that no secondary phase is observed in their single-crystal GaMnN samples that show ferromagnetism [9]. There are also discussions about whether the relevant Mn 3d state has d 4 or d 5 + h character, or whether the d levels are localized in the bandgap or inside the valence band [10].…”