Competition between cubic and uniaxial anisotropy inGa1−xMnxAsin the low-Mn-concentration limit

Abstract

We have studied the dependence of the cubic and uniaxial magnetic anisotropy terms in Ga 1−x Mn x As on temperature T and hole concentration p. For the purpose of this study we prepared a series of Ga 1−x Mn x As layers with low Mn concentration ͑x Ϸ 0.01͒, codoped by Be in the range 3.0ϫ 10 19 Ͻ p Ͻ 8.5ϫ 10 19 cm −3 , and grown on hybrid ZnSe/ GaAs substrates. The use of such hybrid substrates was intended to obtain Ga 1−x Mn x As layers in which-due to the small lattice mismatch between Ga 0.99 Mn 0.01 As and ZnSe-the uniaxial and the cubic anisotropy terms are comparable, so that the contributions of both types of anisotropy could be investigated. The effects of magnetic anisotropy were studied by polar magneto-optical Kerr effect, which allowed us to monitor the reversal process of perpendicular magnetization. The results showed that cubic anisotropy is highly sensitive to both p and T. Specifically, we have found that in samples with high p the cubic anisotropy term is dominant at low T, but decreases rapidly as T increases. In sharp contrast, uniaxial anisotropy shows only a weak dependence on p and T, thus dominating at temperatures close to T C even in samples with high p. These results show that magnetic anisotropy and the magnetization reversal process in Ga 1−x Mn x As can be engineered by an appropriate choice of the temperature and carrier concentration.

Ga1−xMnxAs/piezoelectric actuator hybrids: A model system for magnetoelastic magnetization manipulation

“…Another approach to vary the hole concentration and thus the magnetic properties relies on the introduction of additional nonmagnetic dopant species into GaMnAs, such as Be 28 or Al. 29 The incorporation of hydrogen also allows to control the hole density in GaMnAs.…”

“…Indeed, novel functionalities or physical effects have already been demonstrated in spin-electronic devices based on GaMnAs, such as the emission of circularly polarized light from a socalled spin light emitting diode, 12,16 the controlled motion of domain walls via current pulses, 17,18 the tunneling anisotropic magnetoresistance in GaMnAs/insulator/normal metal structures, 19 and nonvolatile memory device concepts. 4,7,8 One of the most intriguing properties of DMS is the strong dependence of their magnetic properties on nonmagnetic parameters, such as electric field, 20,21 light irradiation, [22][23][24] temperature, [25][26][27] dopant density, 28,29 strain, [30][31][32][33] or pressure. 34 This allows for various control schemes of the magnetic properties of DMS, which we shortly discuss in the following.…”

Observation of a blue shift in the optical response at the fundamental band gap in Ga1−xMnxAs

“…[10][11][12][13] GaMnAs has become the prototype DMS system, representing a model for understanding the nature of ferromagnetic coupling in the III-Mn-V DMS as well as for engineering the magnetic characteristics through tailored growth and processing. [14][15][16] A considerable body of research spanning the past decade has provided insight into the nature of exchange coupling between the Mn and hole spins, [17][18][19][20][21] the character of the magnetic anisotropy, [22][23][24][25] and the role of defects and compensation in determining the magnetic characteristics. 14,16,26,27 Despite these advances, unanswered questions remain with regard to the electronic structure and the appropriate model of ferromagnetic coupling.…”

Spin-Wave Resonance Model of Surface Pinning in Ferromagnetic Semiconductor (Ga,Mn)As Thin Films

“…Gallium manganese arsenide (Ga,Mn)As, created on the basis of the semiconductor gallium arsenide by the addition of a small percentage of manganese as a magnetic dopant, is one of the most intensively studied compounds in this class789101112131415. The free motion of positive charge carriers (holes) throughout the crystal results in the ferromagnetic order of the manganese ions.…”