scholarly journals Высокочастотная ЭПР-спектроскопия парамагнитных центров марганца в кристаллах GaAs : Mn

2021 ◽  
Vol 63 (11) ◽  
pp. 1906
Author(s):  
Р.А. Бабунц ◽  
А.С. Гурин ◽  
И.В. Ильин ◽  
А.П. Бундакова ◽  
М.В. Музафарова ◽  
...  
Keyword(s):  
High Frequency ◽  
Energy Levels ◽  
Exchange Interactions ◽  
Epr Spectra ◽  
Boltzmann Factor ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
Strong Magnetic Fields ◽  
Manganese Ion ◽  
Electron Paramagnetic

High-frequency electron paramagnetic resonance (EPR) is used to study the unique properties of manganese centers in a GaAs:Mn crystal in strong magnetic fields at low temperatures. At frequencies of 94 and 130 GHz, EPR transitions were recorded in the MnGa2+ - SH complex, which is a manganese ion with spin S = 5/2, which replaces gallium (MnGa2+) and is an ionized acceptor (A–) associated via an isotropic antiferromagnetic exchange interaction with a shallow hole (SH) with angular momentum J = 3/2. A complex system of energy levels of this complex in a magnetic field and the possibility of accurately determining exchange interactions from EPR spectra are analyzed. Another complex was investigated, in which an ionized acceptor MnGa2+ interacts with a localized hole center in the form of a diamagnetic ion O2– replacing As. This complex, MnGa2+-OAs2-, is characterized by axial symmetry along the <111> axis of the cubic GaAs crystal and an anisotropic EPR spectrum. Due to the high Boltzmann factor, in our studies, the order of the fine structure spin levels of this complex was determined. The effect of the Boltzmann populations of the energy levels on the high-frequency EPR spectra was also demonstrated for the MnGa2+- SH complex.

Effects of Possible Spin-Spin Interactions on EPR spectra of Cu2+ exchanged Faujasite–X (I)

2005 ◽  
Vol 900 ◽  
Author(s):  
Chrispin B. O. Kowenje ◽  
Barry R. Jones ◽  
Charles W. Kanyi
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Continuous Wave ◽  
Recent Literature ◽  
Epr Spectra ◽  
Spin Hamiltonian ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
Spin Interactions ◽  
Electron Paramagnetic

ABSTRACTThe interpretation of the continuous wave electron paramagnetic resonance (CW-EPR) spectra of Cu2+ exchanged in Faujasite zeolite is not straightforward. Recent literature points to the role of both Cu2+ zeolite sites and Cu2+ relationship to lattice Al in determining the parameters of Cu2+ spin Hamiltonian. Our work shows that at low concentration, Cu2+ EPR signals show negligible spin-spin interactions. At higher Cu (II) concentrations, a third CW-EPR spectrum that has contributions from both the CW-EPR and the spin-spin interactions, appears.

scholarly journals EPR Spectra of Sintered Cd1−xCrxTe Powdered Crystals with Various Cr Content

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3449
Author(s):  
Ireneusz Stefaniuk ◽  
Werner Obermayr ◽  
Volodymyr D. Popovych ◽  
Bogumił Cieniek ◽  
Iwona Rogalska
Keyword(s):  
Curie Temperature ◽  
Room Temperature ◽  
Integral Intensity ◽  
Resonance Field ◽  
Epr Spectra ◽  
Paramagnetic Resonance ◽  
Simple Method ◽  
Paramagnetic Curie Temperature ◽  
Cr Content ◽  
Electron Paramagnetic

In this paper, we show a simple method of producing ferromagnetic materials with a Curie temperature above room temperature. The electron paramagnetic resonance (EPR) spectra of Cd1−xCrxTe (0.002 < x < 0.08) were measured with a dependence on temperature (82 K < T < 381 K). Obtained EPR lines were fitted to a Lorentz-shaped curve. The temperature dependencies of the parameters of the EPR lines, such as the peak-to-peak linewidth (Hpp), the intensity (A), as well as the resonance field (Hr), were studied. Ferromagnetism was noticed in samples at high temperatures (near room temperature). For a sample with a nominal concentration of chrome of x = 0.05, a very strong intrinsic magnetic field is observed. The value of the effective gyromagnetic factor for this sample is ge = 30 at T = 240 K. An increase of chrome concentration above x = 0.05 reduces the ferromagnetic properties considerably. Analysis of the temperature dependencies of the integral intensity of EPR spectra was carried out using the Curie–Weiss law and the paramagnetic Curie temperature was obtained.

The Microscopic Structure Of Shallow Donors In Silicon Carbide

1996 ◽  
Vol 442 ◽  
Author(s):  
J.-M. Spaeth ◽  
S. Greulich-Weber ◽  
M. März ◽  
E. N. Kalabukhova ◽  
S. N. Lukin
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Dependence ◽  
Double Resonance ◽  
Epr Spectra ◽  
Electron Nuclear Double Resonance ◽  
Paramagnetic Resonance ◽  
Vacancy Pair ◽  
Temperature Spectra ◽  
Electron Paramagnetic

AbstractThe electronic structure of nitrogen donors in 6H-, 4H- and 3C-SiC is investigated by measuring the nitrogen hyperfine (hf) interactions with electron nuclear double resonance (ENDOR) and the temperature dependence of the hf split electron paramagnetic resonance (EPR) spectra. Superhyperfine (shf) interactions with many shells of 13C and 29Si were measured in 6H-SiC. The hf and shf interactions are discussed in the framework of effective mass theory. The temperature dependence is explained with the thermal occupation of the lowest valley-orbit split A1 and E states. It is proposed that the EPR spectra of P donors observed previously in neutron transmuted 6H-SiC at low temperature (<10K) and high temperature (>60K) are all due to substitutional P donors on the two quasi-cubic and hexagonal Si sites, whereby at low temperature the E state is occupied and at high temperature the A1 state. The low temperature spectra are thus thought not to be due to P-vacancy pair defects as proposed previously.

Ge-Related Interfacial Defects in Sige Alloy Structures

1995 ◽  
Vol 405 ◽  
Author(s):  
Patricia J. Macfarlane ◽  
M. E. Zvanut ◽  
W. E. Carlos ◽  
M. E. Twigg ◽  
P. E. Thompson
Keyword(s):  
Depth Profile ◽  
Epr Spectra ◽  
Transmission Electron Micrograph ◽  
Dangling Bond ◽  
Electron Micrograph ◽  
Cross Sectional ◽  
Paramagnetic Resonance ◽  
Transmission Electron ◽  
Interfacial Defects ◽  
Electron Paramagnetic

AbstractThis paper reports etching results supporting the identification of the SG1 center as a germanium dangling bond defect at the interface between an oxide and crystalline SiGe. The presence of this defect is significant because, like an analogous center in Si-based systems, it may alter the operation of any microelectronic or micro-optical device which incorporates an interface between SiGe and an overlying oxide. The samples examined are oxygen implanted SiGe layers in which the SG1 center is believed to occur at the interface between oxide precipitates and SiGe. Because of the center's apparent relation to the oxide precipitates distributed through layers of the sample, a depth profile assists in confirming the interfacial nature of the defect. We obtain a depth profile by comparing electron paramagnetic resonance (EPR) spectra of samples etched to decreasing thickness. EPR spectra indicate that the SG1 center decreases with depth in a manner that when correlated to a cross sectional transmission electron micrograph confirms the association with SiO2 and supports its location at the SiGe/SiO2 precipitate interface.

Electron Paramagnetic Resonance of Radicals Formed during Milling

1960 ◽  
Vol 33 (2) ◽  
pp. 462-468 ◽  
Author(s):  
S. E. Bresler ◽  
S. N. Zhurkov ◽  
E. N. Kazbekov ◽  
E. M. Saminskiĭ ◽  
E. E. Tomashevskiĭ
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Gamma Rays ◽  
Epr Spectra ◽  
Mechanical Degradation ◽  
Present Communication ◽  
Surface Layers ◽  
Paramagnetic Resonance ◽  
Mechanical Destruction ◽  
Electron Paramagnetic

Abstract It is well known that during the mechanical degradation of polymers there takes place scission of molecular chains and the formation of macroradicals. It is of considerable interest to study the electron paramagnetic resonance (EPR) spectra of the macroradicals produced by milling, and to compare them with the spectra of the macroradicals formed in the process of polymerization, and also during the irradiation of polymers by gamma rays and neutrons. We may endeavor to compare the amount of macroradicals formed with the extent of mechanical destruction (for instance with the area of the new interface which is formed). In addition, as was found by experience, the macroradicals formed by mechanical scission are good models for the investigation of reactivity since practically all of them are in the newly formed surface layers and are therefore very accessible to various chemical influences. They enter easily into reaction with various agents present in the medium since in this process diffusion from the surface is found in practice not to be a predominating factor. In the present communication we give the first EPR results obtained on mechanically degraded polymers.

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