Mn Interstitial Diffusion in(Ga,Mn)As

Abstract

We present a combined theoretical and experimental study of

Identifying the character of ferromagnetic Mn in epitaxial Fe/(Ga,Mn)As heterostructures

“…The XAS/XMCD arising from Mn-1 has been associated to a mixed-valence ground state due to the large Mn 3d hybridization with the surrounding 4sp states. 19,24,25 Numerical calculations indicated a mixed 80% d 5 -20% d 6 L ground state ͑L is a ligand hole͒. 24,25 In Mn-AP, both the energy shift of the XMCD minimum and the line shape suggest a different valence state with lower occupancy of the 3d levels, implying a lowering of the d 6 character and increment of the d 5 one.…”

“…The latter configuration has a more structured XAS spectrum, located at higher BE with respect to the d 4 -d 5 -d 6 one. [19][20][21][22] A recent detailed study on the depth concentration of Mn in ͑Ga,Mn͒As reveals the presence of Mn with d 5 configuration up to 6 nm from the interface, coexisting with Mn Ga and not related to oxide. 23 Results in Fig.…”

Surface treatments and magnetic properties of Ga1−xMnxAs thin films

“…In these configurations Mn is highly mobile [7] and tends to accumulate on the surface during crystal growth, resulting in non uniform doping profiles and Mn enriched surfaces. Thermal treatments on thin films in gaseous environment, or on As-capped samples [8], are used to remove Mn I thus improving the ferromagnetic properties of the material.…”

Atom-by-atom substitution of Mn in GaAs and visualization of their hole-mediated interactions

“…Mean-field theories based on this scenario have captured the increase of ferromagnetic transition temperature, T c , with doping and other macroscopic properties of Ga 1-x Mn x As 5,6 . Experimental efforts have also shown that improved material quality, achieved through various methods including annealing of random alloy samples, can significantly increase T c even above 150 K [7][8][9][10] . However, currently missing is an accurate microscopic picture, which identifies the precise nature of hole states involved and provides clues on how to enhance ferromagnetism in this compound.…”

“…The significance of the experiments is perhaps best realized by considering the separations between Mn acceptors in randomly doped Ga 1-x Mn x As at concentrations required for the highest reported ferromagnetic temperatures [7][8][9][10] . At 5% doping, 98% of the Mn dopants have one or more neighbour within the sixth nearest-neighbour or closer.…”