Evidence for a magnetic hard gap in the density of states of a magnetic semiconductor near the metal insulator transition (abstract)

1993 ◽  
Vol 73 (10) ◽  
pp. 5750-5750
Author(s):  
T. Penney ◽  
I. Terry ◽  
S. von Molnár ◽  
P. Becla
Keyword(s):  
Density Of States ◽  
Magnetic Semiconductor ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator

scholarly journals Thermodynamic Density of States of Two-Dimensional GaAs Systems near the Apparent Metal-Insulator Transition

2006 ◽  
Vol 96 (21) ◽  
Author(s):  
G. Allison ◽  
E. A. Galaktionov ◽  
A. K. Savchenko ◽  
S. S. Safonov ◽  
M. M. Fogler ◽  
...  
Keyword(s):  
Density Of States ◽  
Insulator Transition ◽  
Two Dimensional ◽  
Metal Insulator Transition ◽  
Metal Insulator

Hopping Conduction Near the Metal-Insulator Transition in CdMnTe:In and Evidence for a Magnetic Hard Gap in the Density of States

1994 ◽  
Vol 08 (07) ◽  
pp. 905-912 ◽  
Author(s):  
I. Terry ◽  
T. Penney ◽  
S. von Molnár ◽  
P. Becla
Keyword(s):  
Carrier Concentration ◽  
Density Of States ◽  
Low Temperatures ◽  
Localization Length ◽  
Insulator Transition ◽  
Variable Range Hopping ◽  
Coulomb Interactions ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Magnetic Polarons

A series of resistivity curves is obtained as a function carrier concentration in just one sample of the dilute magnetic persistent photoconductor Cd0.91Mn0.09Te:In. The measurements, made at carrier concentrations approaching the metal-insulator transition, reveal a cross-over from an exp(To/T)1/2 dependence to an exp(EH/T) form when lowering temperature. The exp(To/T)1/2 dependence is characteristic of variable range hopping in the presence of Coulomb interactions, while the energy EH in the activated form is associated with a hard gap in the density of states that is magnetic in origin. All the data are shown to scale onto a single curve. The localization length. ξ, is found to have the same critical dependence on carrier concentration as that of the measured dielectric constant, κ, when approaching the metal-insulator transition. The temperature dependence of the resistivity is interpreted in terms of the orientation of Mn spins by carriers due to the s-d exchange interaction (the formation of magnetic polarons). This model can also account for the large positive and negative magnetoresistance observed in Cd0.91Mn0.09Te:In at low temperatures.

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.

Spin Polarized Tunneling at the Metal-Insulator Transition

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3723-3725 ◽  
Author(s):  
W. Teizer ◽  
F. Hellman ◽  
R. C. Dynes
Keyword(s):  
Spin Polarization ◽  
Density Of States ◽  
Insulator Transition ◽  
Critical Regime ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Spin Polarized ◽  
Quantum Critical ◽  
Spin Polarized Tunneling

We have determined the spin polarized density of states (DOS) of 3-d amorphous Gd x Si 1-x in the quantum critical regime of a tunable Metal-Insulator Transition (MIT). Using a spin polarized BCS DOS we fit the data and extract the spin polarization P.

Metal-insulator transition in Emery-Anderson model. Density of states calculations

1994 ◽  
Vol 222 (1-2) ◽  
pp. 127-132 ◽  
Author(s):  
V.F. Elesin ◽  
V.A. Kashurnikov ◽  
A.V. Krasheninnikov ◽  
A.I. Podlivaev
Keyword(s):  
Density Of States ◽  
Anderson Model ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator
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