Characterization of microstructural defects from temperature dependence of domain wall coercive field

1998 ◽  
Vol 08 (PR2) ◽  
pp. Pr2-307-Pr2-310 ◽  
Author(s):  
J. Kadlecová ◽  
K. Metlov ◽  
Tomás ◽  
G. Vértesy
Keyword(s):  
Domain Wall ◽  
Temperature Dependence ◽  
Coercive Field ◽  
Microstructural Defects

scholarly journals Temperature dependence of domain‐wall coercive field in magnetic garnet films

1992 ◽  
Vol 71 (7) ◽  
pp. 3462-3466 ◽  
Author(s):  
G. Vértesy ◽  
I. Tomáš ◽  
L. Půst ◽  
J. Pačes
Keyword(s):  
Domain Wall ◽  
Temperature Dependence ◽  
Coercive Field ◽  
Garnet Films ◽  
Magnetic Garnet

Characterization of Er/O-doped Si-LEDs with Low Thermal Quenching

2005 ◽  
Vol 866 ◽  
Author(s):  
A. Karim ◽  
W.-X. Ni ◽  
A. Elfving ◽  
P.O.Å. Persson ◽  
G.V. Hansson
Keyword(s):  
Temperature Dependence ◽  
Reverse Bias ◽  
Thermal Quenching ◽  
Constant Current ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Low Energy Electrons ◽  
Higher Temperature ◽  
Electron Emitters

AbstractElectroluminescence studies of MBE-grown Er/O-doped Si-diodes at reverse bias have been done. For some devices there is much reduced thermal quenching of the emission at 1.54 νm. There are examples where the temperature dependence is abnormal in that the intensity for a constant current even increases with temperature up to e.g. 80 °C. These devices have been studied with cross-sectional transmission electron microscopy to see the microstructure of the Er/O-doped layers as well as the B-doped SiGe-layers that are used as electron emitters during reverse bias. Although there are defects in the layers there is no evidence for large thick precipitates of SiO2. While reduced thermal quenching often is attributed to having the Er-ions within SiO2 layers, this is not the case for our structures as evidenced by our TEM-studies. The origin of the abnormal temperature dependence is attributed to the two mechanisms of breakdown in the reverse-biased diodes. At low temperature the breakdown current is mainly due to avalanche resulting in low-energy electrons and holes that quenches the intensity by Auger deexcitation of the Er-ions. At higher temperature the breakdown current is mainly phonon-assisted tunneling which results in a more efficient pumping with less de-excitation of the Er-ions. Finally at the highest temperatures the thermal quenching sets in corresponding to an activation energy of 125 meV, which is slightly lower than 150 meV that has been reported in other studies.

Characterization of microstructural defects in BF+2‐implanted silicon

1985 ◽  
Vol 58 (8) ◽  
pp. 3032-3038 ◽  
Author(s):  
I. W. Wu ◽  
L. J. Chen
Keyword(s):  
Microstructural Defects

Characterization of carbon aerogels by transport measurements

1993 ◽  
Vol 8 (8) ◽  
pp. 1875-1885 ◽  
Author(s):  
A.W.P. Fung ◽  
Z.H. Wang ◽  
K. Lu ◽  
M.S. Dresselhaus ◽  
R.W. Pekala
Keyword(s):  
Raman Scattering ◽  
Temperature Dependence ◽  
Nearest Neighbor ◽  
Negative Temperature ◽  
Carbon Aerogels ◽  
Free Carriers ◽  
Carbon Particles ◽  
Microcellular Foams ◽  
Temperature Coefficient Of Resistivity

Carbon aerogels are a special class of low-density microcellular foams. These materials are composed of interconnected carbon particles with diameters of approximately 10 nm. The temperature dependence of the dc electrical resistivity and magnetic susceptibility (χ) from 4 K to room temperature, magnetoresistance (MR) in a magnetic field up to 15 T, and Raman scattering were measured as a function of aerogel density. While Raman scattering measurements are not sensitive to variations in density, the χ data show that there are more free carriers in samples of higher density. Aerogel samples with different densities all show a negative temperature coefficient of resistivity and a positive MR. The less dense samples exhibit a stronger temperature dependence of resistivity and a stronger field dependence of the MR, indicating that with decreasing density and increasing porosity, charge carriers are more localized. Data analysis precludes variable-range hopping in favor of nearest-neighbor hopping and fluctuation-induced tunneling as the most likely conduction mechanisms for carbon aerogels.

Abnormal temperature dependence of the coercive field in FePt thin films

2013 ◽  
Vol 347 ◽  
pp. 61-67 ◽  
Author(s):  
J.M. Guzmán ◽  
N. Álvarez ◽  
H.R. Salva ◽  
M. Vásquez Mansilla ◽  
J. Gómez ◽  
...  
Keyword(s):  
Thin Films ◽  
Temperature Dependence ◽  
Coercive Field ◽  
Fept Thin Films ◽  
Abnormal Temperature
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