The Influence of Local Magnetization on Transport in Cd0.91Mn0.09Te:In

1992 ◽  
Vol 290 ◽  
Author(s):  
S. Von Molnar ◽  
T. Penney ◽  
I. Terry ◽  
P. Becla
Keyword(s):  
Transport Properties ◽  
Carrier Concentration ◽  
Magnetic Semiconductors ◽  
Localization Length ◽  
Insulator Transition ◽  
Local Magnetization ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Magnetic Polarons ◽  
Transport Effect

AbstractWe describe the influence of local magnetization on electron localization and transport properties on the insulating side of the metal insulator transition in the dilute magnetic persistent photoconductor Cd0.091 Mn0.09Te:ln. Measurements of both the temperature dependence of the transport properties, and also the dielectric constant, are reported for just one sample in which the carrier concentration n was varied by photodoping. From these results we are able to extract the carrier concentration dependence of the localization length and the permitivity of the electrons. We also report onl a new transport effect which occurs at ultra low temperatures and/or carrier concentrations very close to the metal insulator transition. We find that this mechanism is totally magnetic in origin and are able to explain it in terms of the well devewloped ideas of magnetic polarons in magnetic semiconductors.

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.

Transport properties of two-dimensional hole gas in a Ge1−x Si x /Ge/Ge1−x Si x quantum well in the vicinity of metal-insulator transition

2007 ◽  
Vol 41 (11) ◽  
pp. 1315-1322 ◽  
Author(s):  
Yu. G. Arapov ◽  
V. N. Neverov ◽  
G. I. Harus ◽  
N. G. Shelushinina ◽  
M. V. Yakunin ◽  
...  
Keyword(s):  
Quantum Well ◽  
Transport Properties ◽  
Insulator Transition ◽  
Two Dimensional ◽  
Metal Insulator Transition ◽  
Metal Insulator

Magnetic, Electronic - and Magneto - Transport Properties of Nanocrystalline Nd0.6Sr0.4MnO3 Manganites

2009 ◽  
Vol 67 ◽  
pp. 131-136 ◽  
Author(s):  
Kundu Sourav ◽  
Kumar Nath Tapan
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Transition Temperature ◽  
Curie Temperature ◽  
Transport Properties ◽  
Significant Variation ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Low Field

We have reported in this paper, the effect of grain size in Nd0.6Sr0.4MnO3 .We have investigated the effect of grain size on metal-insulator transition and Curie temperature. We have also reported here the variation of low field magnetoresistance with temperature and grain size. We have observed that the Curie temperature increases monotonically with particle size. The metal insulator transition temperature initially increases with particle size and then gets fixed to a certain value. In these Nd0.6Sr0.4MnO3 nanometric systems, any significant variation of magnetoresistance with particle size is not observed.

TRANSPORT PROPERTIES OF Ag-DOPED La0.7Ca0.3MnO3 THIN FILMS ON SILICON SUBSTRATE

2010 ◽  
Vol 24 (27) ◽  
pp. 5451-5456 ◽  
Author(s):  
H. C. JIANG ◽  
W. L. ZHANG ◽  
X. F. CAO ◽  
W. X. ZHANG ◽  
B. PENG
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Transport Properties ◽  
Silicon Substrate ◽  
Annealing Temperature ◽  
Rf Magnetron Sputtering ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Higher Temperature

Ag -doped La 0.7 Ca 0.3 MnO 3 (LCMO) films were prepared on silicon substrate by RF magnetron sputtering. The dependences of transport properties on annealing temperature were explored. It is shown that the resistivity of the samples decreases and the metal–insulator transition temperature shifts to higher temperature with the increase in annealing temperature. Two metal–insulator transition temperatures are presented in the R – T plots of Ag -doped LCMO films, which can be explained by the Ag 1+ substitution of La 3+ to form La 1-x Ag x MnO 3 compound. Compared with LCMO thin films, Ag -doping can observably improve the TM-I and decrease the resistivity of the samples.

The metal-insulator transition in magnetic semiconductors: Transport in Gd −x v x S 4

1985 ◽  
Vol 28 (1-2) ◽  
pp. 127-130 ◽  
Author(s):  
S. von Molnár ◽  
J. Flouquet ◽  
F. Holtzberg ◽  
G. Remenyi
Keyword(s):  
Magnetic Semiconductors ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator

scholarly journals Fabrication and Transport Properties of Manganite-Polyacrylamide-Based Composites

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Viorel Sandu ◽  
Stelian Popa ◽  
Ion Ivan ◽  
Carmen Plapcianu ◽  
Elena Sandu ◽  
...  
Keyword(s):  
Transport Properties ◽  
Insulator Transition ◽  
Electric Transport ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Poly Acrylamide

We present the fabrication and transport properties of a series of composites made ofLa2/3Sr1/3MnO3and acrylamide-based copolymers. The most important result is the very narrow transition, of only 27 K, displayed by the peak that appears around the metal-insulator transition of the composites made with poly(acrylamide-vinylacetate). Although the amount of polymer is rather low, different copolymers change drastically the electric transport characteristics.

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