scholarly journals Metal-insulator transition and the character of the hole impurity bands in ferromagnetic GaMnAs disordered dilute magnetic semiconductor

2008 ◽  
Vol 1118 ◽  
Author(s):  
R. da Silva Neves ◽  
A. Ferreira da Silva ◽  
R. Kishore
Keyword(s):  
Dilute Magnetic Semiconductor ◽  
Critical Concentration ◽  
Mean Field ◽  
Magnetic Semiconductor ◽  
Impurity Band ◽  
Insulator Transition ◽  
Ferromagnetic Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
The Mean

ABSTRACTThe study of ferromagnetic transition of Ga1-xMnxAs dilute magnetic semiconductor (DMS) is much of interest mainly due to the potential application in spintronic devices. Based on the mean field approach we present the average contribution of the hole spins by considering the holes in an impurity band (IB) and the critical concentration for the metal-insulator transition (MIT) in this semiconductor. In order to calculate the mean configuration of spins of impurities Mn+2 we use a formalism proposed for a spatial disordered system. The results for the metallic densities around the MIT transition are compared to experimental results and other theoretical findings.

THE EFFECT OF HYDROSTATIC PRESSURE ON METAL–INSULATOR TRANSITION IN QUANTUM WELL SEMICONDUCTOR SYSTEMS II

2005 ◽  
Vol 04 (01) ◽  
pp. 45-53 ◽  
Author(s):  
A. JOHN PETER
Keyword(s):  
Hydrostatic Pressure ◽  
Quantum Well ◽  
Ionization Energy ◽  
Critical Concentration ◽  
Shallow Donor ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Mass Approximation ◽  
The One

Using a variational procedure within the effective mass approximation, the ionization energies of a shallow donor in a quantum well (QW) of GaAs/Ga 1-x Al x As superlattice system under the influence of pressure with the exact dielectric function are obtained. The vanishing of ionization energy initiating Mott transition is observed within the one-electron approximation. The effects of Anderson localization using a simple model, and exchange and correlation in the Hubbard model are included in this model. It is found that the ionization energy (i) increases when well width increases for a given pressure, (ii) decreases and reaches a bulk value for a larger well width, (iii) increases with increasing external hydrostatic pressure for a given QW thickness, and (iv) the critical concentration at which the metal–insulator transition (MIT) occurs is increased when pressure is applied. It also is demonstrated that MIT is not possible in a hydrostatic pressure in a quantum well supporting scaling theory of localization. All the calculations have been carried out with finite and infinite barriers and the results are compared with available data in the literature.

Sign in / Sign up

Export Citation Format

Share Document