scholarly journals Electrical Conductivity and Magnetoresistance of Silicon Microstructures in the Vicinity to Metal-Insulator Transition

2019 ◽  
Vol 19 (3) ◽  
pp. 246-253
Author(s):  
Yu.М. Khoverko ◽  
N.О. Shcherban
Keyword(s):  
Magnetic Fields ◽  
Low Temperatures ◽  
Magnetic Impurity ◽  
Specific Resistance ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Strong Magnetic Fields ◽  
Silicon Microstructures ◽  
Physical Quantities ◽  
Diluted Magnetism

Complex research of silicon microcrystals with specific resistance from ρ300K = 0.025 Ohm × cm to ρ300K =0.007 Ohm × cm doped with boron transport impurity to concentrations corresponding to the transition of metaldielectric and modified transition metal nickel at low temperatures to the temperature of liquefied heliumT = 4.2 K in magnetic fields up to 14 Tl. The features of electrophysical characteristics of samples at lowtemperatures in strong magnetic fields up to 14 Tl are determined due to the influence of a magnetic impurity insemiconductor-diluted magnetism and the use of such crystals in sensors of physical quantities (temperature,magnetic field, deformation) is proposed.

scholarly journals The change of resistance of gold crystals at very low temperatures in a magnetic field and supra-conductivity

1930 ◽  
Vol 126 (803) ◽  
pp. 683-695 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Low Temperatures ◽  
Crystalline State ◽  
Specific Resistance ◽  
Systematic Research ◽  
Continuous Curve ◽  
Strong Magnetic Fields ◽  
Relative Change ◽  
The Magnetic Field

In a paper published last year the author described a systematic research on the change of resistance which occurs in a number of metals in strong magnetic fields. As a result of these investigations the following formulæ expressing the relative change of resistance ∆R/R o with the field H were found to hold :— ∆R/R o = β' H 2 /3H k H ≼ H k , (1) and ∆R/R o = β' ( H-H k +H k 2 /3H) H ≽ H k , (2) where β' and H k are constant for a given sample of a metal and at a given temperature. These two expressions form a continuous curve, and it is evident that the formula (1) which holds for the weaker fields, shows that the resistance increases as the square of H, and formula (2) indicates that the change of resistance in strong fields approaches a linear law. These two formulæ have been obtained mathematically on the following assumption. It is known that in a metal which is not in a perfect crystalline state, and which contains even small traces of impurities, there exists a disturbance which increases its specific resistance. My hypothesis was that a magnetic field increases the specific resistance in a similar way to these imperfections, so that they are equivalent to an internal magnetic field H k , orientated at random. Then, if the metal is brought under the influence of an outside magnetic field H, the increase of resistance is such as would be produced by a combination of the two fields. Further, I assumed that the increase of resistance is proportional to the magnetic field, and this led to formulæ (1) and (2) which appear to fit all my experimental results very well. Several important consequences follow from this hypothesis.

Noise in illuminated GaAs/AlGaAs heterostructures at low temperatures and in strong magnetic fields

1989 ◽  
Vol 71 (12) ◽  
pp. 1067-1071
Author(s):  
A.J. Kil ◽  
R.J.J. Zijlstra ◽  
M.F.H. Schuurmans ◽  
J.P. André
Keyword(s):  
Magnetic Fields ◽  
Low Temperatures ◽  
Strong Magnetic Fields

Magnetic field-induced metal-insulator transition in InP: new result at very low temperatures

1984 ◽  
Vol 17 (16) ◽  
pp. L411-L416 ◽  
Author(s):  
G Biskupski ◽  
H Dubois ◽  
J L Wojkiewicz ◽  
A Briggs ◽  
G Remenyi
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
Insulator Transition ◽  
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.

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