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1

Nature of Donors in SiC

100%

Suchanek B., Dwiliński R., Kamińska M., Palczewska M., Vlaskina S.

Acta Physica Polonica A

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1995

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vol. 87

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issue 2

321-324

EN

6H-SiC samples were examined by ESR technique in temperature range from 5 K up to 300 K. Two kinds of ESR lines were observed: a single line at g = 2.0054 ± 0.0007, called X-line, and a triplet corresponding to isolated nitrogen defect. Ionization energy of X defect was determined as about 60 meV and the ionization energy of isolated nitrogen was determined as about 200 meV below SiC conduction band.

2

EPR in Kagome Staircase Compound Mg_{2.997}Co_{0.003}V_2O_8

63%

Aleshkevych P., Fink-Finowicki J.

Acta Physica Polonica A

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2007

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vol. 111

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issue 1

105-110

EN

The paramagnetic resonance of Co^{2+} ions in Mg_{2.997}Co_{0.003}V_2O_8 single crystals are reported. The EPR spectrum shows two groups of resonance lines associated with two crystallographically nonequivalent Co ions positions that are known in the kagome staircase system as "cross-tie" and "spine" sites. No preferential occupation of Co^{2+} ions in the kagome lattice was observed. The ground state was described by spin-Hamiltonian with an effective electronic spin S=1/2 and nuclear spin I=7/2. The local symmetry of oxygen octahedron surrounding Co ions, main values of the g-factors, and hyperfine structure were determined for both cobalt positions.

3

Electron Paramagnetic Resonance Study of Se-Doped AlSb: Evidence for Negative-U of the DX Center

63%

Stallinga P., Walukiewicz W., Weber E. R., Becla P., Lagowski J.

Acta Physica Polonica A

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1995

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vol. 88

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issue 5

1043-1047

EN

A metastable electron paramagnetic resonance signal is observed in Se doped AlSb. After illumination a strong, persistent electron paramagnetic resonance signal with an isotropic g-factor of 1.949 is observed. The absence of any electron paramagnetic resonance when cooled in the dark is direct evidence for the negative-U model. The electron paramagnetic resonance arises from the effective-mass state of the defect, which is not filled at thermal equilibrium. An analysis of the lineshape reveals that the linewidth is determined by hyperfine interactions. The extend of the wave function is found to be comparable to the prediction for the effective-mass state.

4

Effect of Neutron Irradiation on the EPR Spectra of CuGeO_{3}

51%

Mosiniewicz-Szablewska E., Gładczuk L., Dąbkowska H., Pytel B., Szymczak H.

Acta Physica Polonica A

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2000

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vol. 97

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issue 5

897-900

EN

The influence of neutron irradiation on the electron paramagnetic resonance spectra of the spin-Peierls compound CuGeO_{3} was investigated in the wide temperature range 2-300 K. It was found that the irradiation induced appreciable changes in the EPR signal intensity, resonance line width and g-factor of this material. It was also shown that the irradiation leads to a decrease in the spin-Peierls transition temperature. For higher irradiation doses, an antiferromagnetically ordered phase can be observed at lower temperatures. This phase coexists with the spin-Peierls phase. The observed decrease in the spin-Peierls transition temperature after irradiation may be associated with some changes in topological and chemical short-range order or with the transmutation of the fraction of ^{63}Cu in the ^{63}Cu(n,α)^{60}Co reaction.

5

Low-Symmetry Aspects in EPR Spectra of Mn^{2+} at Bi^{3+} Sites in BiVO_{4} Single Crystal

51%

Yeom T., Choh S., Rudowicz C.

Acta Physica Polonica A

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1992

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vol. 82

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issue 3

503-510

EN

Zero-field splitting parameters obtained from EPR X-band experiments of Baran et al. (1985) and Yeom et al. (1992) are reanalyzed. Transformation relations are derived to express the two sets of data in the same axis system. Problems arising from using a truncated zero-field splitting Hamiltonian in fitting the experimental data are elucidated. Low-symmetry aspects in EPR spectra of Mn^{2+} at Bi^{3+} sites in BiVO_{4} single crystal are considered. Good agreement for orthorhombic parameters b^{0}_{2} and b^{2}_{2} is obtained indicating that the centres observed in the two cases are the same Mn centres. The remaining b^{q}_{k} parameters accounting for the actual site symmetry around Mn^{2+} impurity which seems to be lower than orthorhombic in the ferroelastic phase cannot be unambiguously determined from the existing EPR data.

6

Effect of Heavy Ion Irradiation on the Magnetic Properties of CuGeO_{3}

51%

Gładczuk L., Mosiniewicz-Szablewska E., Szymczak R., Baran M., Dąbkowska H., Choiński J., Czosnyka T., Szymczak H.

Acta Physica Polonica A

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2000

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vol. 97

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issue 5

871-874

EN

The influence of heavy ion irradiation on the magnetic properties of the spin-Peierls compound CuGeO_{3} has been investigated by means of the electron paramagnetic resonance, the spontaneous magnetization, and the low field ac susceptibility. The measurements were performed on the CuGeO_{3} single crystals before and after irradiation with 80 MeV oxygen ions in the wide temperature range of 2-300 K. It was found that the irradiation induced an increase in the EPR signal intensity, magnetization, and susceptibility of this material. It was also shown that the irradiation does not lead to a decrease in the spin-Peierls transition temperature and to the formation of an antiferromagnetic phase which is expected to appear in disordered spin-Peierls systems.

7

EPR and Spectral Studies of a Molecular and Crystal Structure of Cu (3,5-dimethylpyridine)_{3}(NO_{3})_{2}

51%

Hoffmann S., Goher M., Hilczer W., Goslar J., Hafez A.

Acta Physica Polonica A

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1994

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vol. 85

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issue 3

517-530

EN

X-band single crystal EPR, IR and UV-VIS data are used to deduce a molecular and crystal structure of a new compound with a chemical formula Cu(3,5-dimethylpyridine)_{3}(NO_{3})_{2}. EPR shows that four magnetically inequivalent molecules exist in the crystal unit cell of C_{4v} symmetry. IR spectra suggested that both monodentate and bidentate NO_{3}-groups exist in the crystal. A most probable Cu(II) complex geometry with d_{x²-y²} ground state is a square pyramid with three nitrogens from 3,5-dimethylpyridine molecules and one oxygen from monodentate nitrato group in a basal plane and an oxygen from NO_{3}-group in apical position. There exists a chemical contact between complexes as it is indicated by the exchange interaction with |J| ≤ 1 cm^{-1}. It suggests that square pyramid complexes are arranged in polymeric chains with semi-coordination of bidentate NO_{3}-group to the adjacent Cu(II) ion. An extended analysis of an exchange averaging effect between EPR lines from two and four Cu(II) sites is presented with equations relating molecular and crystal g-factors.

Refine search results

Nature of Donors in SiC

EPR in Kagome Staircase Compound Mg_{2.997}Co_{0.003}V_2O_8

Electron Paramagnetic Resonance Study of Se-Doped AlSb: Evidence for Negative-U of the DX Center

Effect of Neutron Irradiation on the EPR Spectra of CuGeO_{3}

Low-Symmetry Aspects in EPR Spectra of Mn^{2+} at Bi^{3+} Sites in BiVO_{4} Single Crystal

Effect of Heavy Ion Irradiation on the Magnetic Properties of CuGeO_{3}

EPR and Spectral Studies of a Molecular and Crystal Structure of Cu (3,5-dimethylpyridine)_{3}(NO_{3})_{2}