Intrinsically limited critical temperatures of highly dopedGa1−xMnxAsthin films

Abstract

Ga 1−x Mn x As films with exceptionally high saturation magnetizations of Ϸ100 emu/ cm 3 corresponding to effective Mn concentrations of x ef f Ϸ 0.10 still have a Curie temperature T C smaller than 195 K contradicting mean-field predictions. The analysis of the critical exponent ␤ of the remnant magnetization-␤ = 0.407͑5͒-in the framework of the models for disordered /amorphous ferromagnets suggests that this limit on T C is intrinsic and due to the short range of the ferromagnetic interactions resulting from the small mean-free path of the holes. This result questions the perspective of room-temperature ferromagnetism in highly doped GaMnAs.

Structural and magnetic characteristics of MnAs nanoclusters embedded in Be-doped GaAs

“…1 Significant effort has been invested in this context in understanding and improving the properties of the ferromagnetic semiconductor (Ga,Mn)As. 2,3 Despite remarkable advances in recent years that include an enhancement of the Curie temperature to about 195 K, 4 as well as the demonstration of novel functionality such as electrically modulated magnetization, 5 the technological potential of (Ga,Mn)As still remains elusive. However, the material provides an excellent model system for testing new semiconductor spintronic device concepts.…”

Properties of (Ga,Mn)As codoped with Li

“…The magnetization at 5 K increases with increasing x, and reaches $140 mT for x $ 0.15, which is the highest magnetization for (Ga,Mn)As obtained so far. 9,24 The result indicates that Li codoping indeed increases x eff . Figure 3(b) shows the t a dependence of T C for Ga 0.96 Mn 0.04 As with and without Li.…”

Magnetism and magnetoresistance in the critical region of a dilute ferromagnet

“…However, due to the intrinsic disorder present in randomly substituted dilute ferromagnetic semiconductors such as (Ga,Mn)As, the accessible critical region is limited to reduced temperatures |t|< 0.025. Any long-range inhomogeneities in the samples will further limit the critical region and may be responsible for some apparently contradictory results in earlier studies [11][12][13][14][15] . Hence, the observed good agreement of the field-induced magnetization with the three-dimensional Heisenberg model, as shown in Fig.…”

“…Studies of critical behavior of the magnetization in dilute ferromagnetic semiconductors have produced disparate and contradictory results [11][12][13][14][15] (see Ref. 16 for a detailed discussion).…”