scholarly journals Investigation of the electron and thermal transport in rare-earth nitrides

2021 ◽  
Author(s):  
◽  
Tanmay Maity
Keyword(s):  
Transition Temperature ◽  
Temperature Dependence ◽  
Hall Effect ◽  
Carrier Concentration ◽  
Vacancy Concentration ◽  
Nitrogen Vacancy ◽  
Band Structure Calculation ◽  
Strong Temperature Dependence ◽  
Ferromagnetic Transition ◽  
Gadolinium Nitride

<p>Gadolinium nitride (GdN) and samarium nitride (SmN) have been widely studied to understand their ferromagnetic ordering and electronic structure, and for their promise in spintronics applications. This thesis presents experimental magnetotransport studies of GdN and SmN films in which experimental results have been compared with the existing band structure calculation. Three GdN films have been prepared in different conditions, among them two films are epitaxial quality and one film is polycrystalline in nature, and two films of SmN were also studied. Their magnetic properties were probed by SQUID magnetometry and they are found to be ferromagnetic. The transition temperature differs from sample to sample and this behaviour has been attributed to the presence of magnetic polarons that nucleate around nitrogen vacancies and give rise to an inhomogeneous ferromagnetic state.  The charge transport results have been discussed for all GdN and SmN films. A full set of charge/heat transport results are obtained on only one epitaxial GdN. The difference of resistivity among these samples is noticeable. The Hall effect results show the presence of different carrier concentration with at most only weak temperature dependence. We also have noticed the presence of anomalous Hall effect in the paramagnetic region for a lower-concentration epitaxial GdN.  The thermopower in both GdN and SmN was measured to provide further insight into the material’s electronic properties. In this thesis we present the first experimental investigation of the thermopower of epitaxial gadolinium nitride and samarium nitride films, measured using an experimental set-up designed for measuring the temperature dependent thermopower of thin films. Our result shows a negative thermopower for both GdN and SmN films and simple, though strong temperature dependence. At low temperatures we observe a peak near the ferromagnetic transition temperature in GdN. The results are interpreted in terms of the diffusion thermopower.  Overall the results suggest that the nitrogen vacancy concentration controls the carrier concentration and plays a significant role towards the transport properties. We conclude that all films are either heavily, moderately or weakly doped semiconductors with a metallic characteristic.</p>

scholarly journals Investigation of the electron and thermal transport in rare-earth nitrides

2021 ◽  
Author(s):  
◽  
Tanmay Maity
Keyword(s):  
Transition Temperature ◽  
Temperature Dependence ◽  
Hall Effect ◽  
Carrier Concentration ◽  
Vacancy Concentration ◽  
Nitrogen Vacancy ◽  
Band Structure Calculation ◽  
Strong Temperature Dependence ◽  
Ferromagnetic Transition ◽  
Gadolinium Nitride

<p>Gadolinium nitride (GdN) and samarium nitride (SmN) have been widely studied to understand their ferromagnetic ordering and electronic structure, and for their promise in spintronics applications. This thesis presents experimental magnetotransport studies of GdN and SmN films in which experimental results have been compared with the existing band structure calculation. Three GdN films have been prepared in different conditions, among them two films are epitaxial quality and one film is polycrystalline in nature, and two films of SmN were also studied. Their magnetic properties were probed by SQUID magnetometry and they are found to be ferromagnetic. The transition temperature differs from sample to sample and this behaviour has been attributed to the presence of magnetic polarons that nucleate around nitrogen vacancies and give rise to an inhomogeneous ferromagnetic state.  The charge transport results have been discussed for all GdN and SmN films. A full set of charge/heat transport results are obtained on only one epitaxial GdN. The difference of resistivity among these samples is noticeable. The Hall effect results show the presence of different carrier concentration with at most only weak temperature dependence. We also have noticed the presence of anomalous Hall effect in the paramagnetic region for a lower-concentration epitaxial GdN.  The thermopower in both GdN and SmN was measured to provide further insight into the material’s electronic properties. In this thesis we present the first experimental investigation of the thermopower of epitaxial gadolinium nitride and samarium nitride films, measured using an experimental set-up designed for measuring the temperature dependent thermopower of thin films. Our result shows a negative thermopower for both GdN and SmN films and simple, though strong temperature dependence. At low temperatures we observe a peak near the ferromagnetic transition temperature in GdN. The results are interpreted in terms of the diffusion thermopower.  Overall the results suggest that the nitrogen vacancy concentration controls the carrier concentration and plays a significant role towards the transport properties. We conclude that all films are either heavily, moderately or weakly doped semiconductors with a metallic characteristic.</p>

scholarly journals Doping and Mobility Profiles in Defect-Engineered Ultra-shallow Junctions: Bulk and SOI

2004 ◽  
Vol 810 ◽  
Author(s):  
A. J. Smith ◽  
B. Colombeau ◽  
R. Gwilliam ◽  
E. Collart ◽  
N.E.B. Cowern ◽  
...  
Keyword(s):  
Hall Effect ◽  
Carrier Concentration ◽  
Vacancy Concentration ◽  
Depth Resolution ◽  
Silicon On Insulator ◽  
Bulk Silicon ◽  
Near Surface ◽  
Silicon Ions ◽  
Shallow Junctions ◽  
Ultra Shallow Junctions

ABSTRACTSilicon on insulator (SOI - Smartcut®) wafers were implanted with 1MeV and 300keV silicon ions to doses of 3.8x1015 cm−2 and 3x1014 cm−2, respectively, in order to modify the vacancy concentration in a controlled way. Boron was then implanted at 2keV to a dose of 1×1015 cm−2 into the near-surface part of the vacancy-engineered region. Atomic profiles were determined using SIMS and electrical profiles were measured using a novel Differential Hall Effect (DHE) technique, which enables profiling of electrically active dopants with a nanometer depth resolution. The electrical profiles provide pairs of carrier concentration and mobility values as a function of depth. The buried oxide (BOX) is proven to restrict the back diffusing interstitials positioned below the BOX from entering the silicon top layer and interacting with the boron profile. Also an increase of ∼50% in boron activation is achieved when a co-implant is used. However, SOI shows a reduced degree of activation when compared to bulk silicon, with or without a co-implant.

THE EFFECT OF THE LAYERED TO PHONONS ON CARRIER DISTRIBUTION IN SUPERCONDUCTING OXIDES

1990 ◽  
Vol 04 (15) ◽  
pp. 949-953
Author(s):  
HANTING WANG ◽  
WENZHEN WANG ◽  
SHIJIE XIONG
Keyword(s):  
Temperature Dependence ◽  
Hall Effect ◽  
Carrier Concentration ◽  
Layered Structure ◽  
Statistical Estimate ◽  
Linear Temperature Dependence ◽  
Carrier Distribution ◽  
Linear Temperature ◽  
Superconducting Oxides

The effect of layered TO phonons on the carrier concentration of superconducting oxides with layered structure is theoretically investigated. The origin of this effect is the removal of the degeneracy of the carrier subbands for the equivalent conducting sheets. The degeneracy of two neighbouring conducting sheets can be removed by the lattices distortions due to the z-polarized vibrations of the TO phonons in the mediating insulating plane, the carrier distribution is then shifted. A statistical estimate shows a linear temperature dependence of carrier concentration. The relevance of this result to the unusual temperature dependence of the Hall effect is discussed.

Temperature Dependence of the Critical Electron Dose for Fatty Acid Monolayers

1982 ◽  
Vol 40 ◽  
pp. 78-79
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Fatty Acid ◽  
Inelastic Scattering ◽  
Temperature Dependence ◽  
Structural Damage ◽  
Direct Result ◽  
Second Step ◽  
Strong Temperature Dependence ◽  
Electron Dose ◽  
Covalent Bonds

The structural damage of molecules irradiated by electrons is generally considered to occur in two steps. The direct result of inelastic scattering events is the disruption of covalent bonds. Following changes in bond structure, movement of the constituent atoms produces permanent distortions of the molecules. Since at least the second step should show a strong temperature dependence, it was to be expected that cooling a specimen should extend its lifetime in the electron beam. This result has been found in a large number of experiments, but the degree to which cooling the specimen enhances its resistance to radiation damage has been found to vary widely with specimen types.

Effect of Cu doping on the electrical Properties of ZnTe by Vacuum Thermal Evaporation

2018 ◽  
Vol 31 (3) ◽  
pp. 20
Author(s):  
Sarmad M. M. Ali ◽  
Alia A.A. Shehab ◽  
Samir A. Maki
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Hall Effect ◽  
Carrier Concentration ◽  
Hall Mobility ◽  
Cu Doping ◽  
Before And After ◽  
Hall Effect Measurements ◽  
Evaporation Technique ◽  
P Type

In this study, the ZnTe thin films were deposited on a glass substrate at a thickness of 400nm using vacuum evaporation technique (2×10-5mbar) at RT. Electrical conductivity and Hall effect measurements have been investigated as a function of variation of the doping ratios (3,5,7%) of the Cu element on the thin ZnTe films. The temperature range of (25-200°C) is to record the electrical conductivity values. The results of the films have two types of transport mechanisms of free carriers with two values of activation energy (Ea1, Ea2), expect 3% Cu. The activation energy (Ea1) increased from 29meV to 157meV before and after doping (Cu at 5%) respectively. The results of Hall effect measurements of ZnTe , ZnTe:Cu films show that all films were (p-type), the carrier concentration (1.1×1020 m-3) , Hall mobility (0.464m2/V.s) for pure ZnTe film, increases the carrier concentration (6.3×1021m-3) Hall mobility (2m2/V.s) for doping (Cu at 3%) film, but  decreases by increasing Cu concentration.

scholarly journals Temperature-Driven Spin Reorientation Transition in CoPt/AlN Multilayer Films

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Wupeng Cai ◽  
Shinji Muraishi ◽  
Ji Shi ◽  
Yoshio Nakamura ◽  
Wei Liu ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Mean Field ◽  
Multilayer Films ◽  
Spin Reorientation ◽  
Strong Temperature Dependence ◽  
Mean Field Model ◽  
Spin Reorientation Transition ◽  
Magnetoelastic Effect ◽  
Out Of Plane ◽  
Interface Anisotropy

Spin reorientation transition phenomena from out-of-plane to in-plane direction with increasing temperature are observed for the 500°C annealed CoPt/AlN multilayer films with different CoPt layer thicknesses. CoPt-AlN interface and volume anisotropy contributions, favoring out-of-plane and in-plane magnetization, respectively, are separately determined at various temperatures. Interface anisotropy exhibits much stronger temperature dependence than volume contribution, hence the temperature-driven spin reorientation transition occurs. Interface anisotropy in this work consists of Néel interface anisotropy and magnetoelastic effect. Magnetoelastic effect degrades rapidly and changes its sign from positive to negative above 200°C, because of the involvement of stress state in CoPt films with temperature. By contrast, Néel interface anisotropy decays slowly, estimated from a Néel mean field model. Thus, the strong temperature dependence of CoPt-AlN interface anisotropy is dominated by the change of magnetoelastic effect.

TEMPERATURE DEPENDENCE OF THE HALL EFFECT IN La2−xSrxCuO4 AND ABa2Cu3O7 (A=Y, Gd) HIGH TEMPERATURE SUPERCONDUCTORS

1987 ◽  
Vol 01 (03n04) ◽  
pp. 1067-1070 ◽  
Author(s):  
M. Petravić ◽  
A. Hamzić ◽  
B. Leontić ◽  
L. Forró
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Hall Effect ◽  
Normal State ◽  
High Temperature Superconductors ◽  
The Other ◽  
Hall Constant ◽  
High Temperature Superconducting ◽  
Superconducting Ceramics ◽  
Hall Effect Measurements

We present Hall effect measurements in the normal state of the high temperature superconducting ceramics La2−xSrxCuO4 (x=0, 0.1, 0.15, 0.2, 0.25, 0.3), YBa2Cu3o7 and GdBa2Cu3O7 . The first family has temperature independent Hall constant for x>0, while in the other two systems RH is proportional to 1/T. From the Hall effect it follows that the transport in these compounds is hole-like.

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