scholarly journals Temperature dependence of the electronic structure of theJeff=12Mott insulatorSr2IrO4studied by optical spectroscopy

2009 ◽  
Vol 80 (19) ◽  
Author(s):  
S. J. Moon ◽  
Hosub Jin ◽  
W. S. Choi ◽  
J. S. Lee ◽  
S. S. A. Seo ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Temperature Dependence ◽  
Optical Spectroscopy

Electronic structure of half-metallicCrO2as investigated by optical spectroscopy

2000 ◽  
Vol 61 (8) ◽  
pp. R5062-R5065 ◽  
Author(s):  
R. Yamamoto ◽  
Y. Moritomo ◽  
A. Nakamura
Keyword(s):  
Electronic Structure ◽  
Optical Spectroscopy

Optical Spectroscopy of Mixed Metamagnetic FexCo1-xCl2 Crystals

1980 ◽  
Vol 35 (10) ◽  
pp. 1013-1019 ◽  
Author(s):  
Friedrich Seitz ◽  
Terence E. Wood ◽  
Peter Day
Keyword(s):  
Charge Transfer ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Absorption Spectra ◽  
Optical Spectroscopy ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Broad Band ◽  
Mixed Crystals ◽  
Magnetic Exchange

Abstract Electronic absorption spectra are reported for single crystals of composition FexCo1-xCl2 as a function of temperature from 300 K to 4 K. A broad band at 436 nm is assigned to Fe (II) → Co (II) charge transfer and the temperature dependence of its intensity is related to the magnetic exchange between the ions. The 2T1g(2H) excitation of Co (II) in the mixed crystals has an unusual temperature dependence which correlates with the Néel temperature.

Isotope Effect of the Pure 35Cl and 37Cl Quadrupole Resonance Spectra in CHCl2COOH and CDCl2COOD

1977 ◽  
Vol 32 (5) ◽  
pp. 415-419 ◽  
Author(s):  
Helmut Rager ◽  
Alexander Wergin
Keyword(s):  
Electronic Structure ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Small Difference ◽  
Electric Field Gradient Tensor ◽  
Gradient Tensor ◽  
Chlorine Isotopes ◽  
Resonance Frequencies ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Abstract The temperature dependence of the pure nuclear quadrupole resonance of 35Cl and 37Cl in solid CHCl2COOH and CDCl2COOD has been measured. The spectra are doublets according to two dif­ferent sites, Cl (I) and Cl (II), of the chlorine atoms in the CXCl2 group (X = H,D). In CHCl2COOH and CDCl2COOD the 37Cl spectra became unobservable above 198 K and 175 K and the 35Cl spectra vanished at 238 K and 226 K, respectively. The temperature dependence was calculated using the Bayer-Kushida theory which gives a satisfactory approach in the case of the compounds investigated here. A small difference has been found in the temperature dependence of the resonance frequen­ cies for CI (I) and CI (II) in both the CHCl2 and CDCl2 group, which is probably due to differences in the bond lengths of CI (I) and CI (II). Furthermore, there is a different temperature dependence of the resonance frequencies of the chlorine isotopes at the sites CI (I) and CI (II). This gives evi­ dence for the so-called isotope effect: i. e. there are slightly different thermal motions for the chlorine isotopes which are involved in the averaging of the electric field gradient tensor. The re­ placement of protons by deuterons gave a shift of the resonance frequencies of about 20 kHz to lower values. This may be primarily caused by effects of deuteration on the electronic structure.

Optical spectroscopy and electronic structure of the Er5Ge3 compound

2014 ◽  
Vol 56 (9) ◽  
pp. 1737-1741 ◽  
Author(s):  
Yu. V. Knyazev ◽  
A. V. Lukoyanov ◽  
Yu. I. Kuz’min
Keyword(s):  
Electronic Structure ◽  
Optical Spectroscopy

ELECTRONIC STRUCTURE AND CONDUCTIVITY OF HYDROCARBON FILMS OBTAINED IN PLASMA DISCHARGES OF TOKAMAK T-10

1970 ◽  
Vol 61 (11) ◽  
Author(s):  
Galina A. Sokolina ◽  
Igor I. Arkhipov ◽  
Nikolay Yu. Svechnikov ◽  
Sergey A. Grashin
Keyword(s):  
Activation Energy ◽  
Electronic Structure ◽  
Temperature Dependence ◽  
Direct Current ◽  
Plasma Discharges ◽  
X Ray ◽  
Hydrocarbon Films ◽  
Direct Current Conductivity ◽  
Current Voltage ◽  
Current Voltage Characteristics

Amorphous hydrocarbon films on silicon substrates obtained in the chamber of tokamak T-10 with space-bounded deuterium plasma by carbon diaphragms were studied. Using the methods of spectrophotometry, ellipsometry, X-ray photoemission spectroscopy and X-ray excited Auger electron spectroscopy, it was established that the refraction and absorption coefficients of films, as well as the parameters of the electronic structure such as the magnitude of the band gap, the fraction of sp2-hybridized carbon and the chemical composition of impurities depend on the characteristics of the discharge in the tokamak. It is shown that the deposited films refer to high-resistance dielectrics, and they can be classified by optical properties as hard or soft amorphous hydrocarbon films, depending on the type of the plasma discharge (pulse working discharge or long-term low-energy cleaning discharge). Wherein, the conductivity of hard films is less than that of soft films, which corresponds to a smaller fraction of sp2-states of carbon in these films and to a higher value of the band gap. The current-voltage characteristics and the temperature dependence of the direct current conductivity of hard and soft films were measured. It was shown that in the temperature range of 293–550 K, the conductivity is determined by the hopping conductivity mechanism over localized states near the Fermi level and the boundaries of the allowed bands. The hopping conductivity mechanism is also indicated by the power law obtained at room temperature at alternating current with a value of a power exponent close to 0.8. The measurement of the current-voltage characteristics and the temperature dependence of the conductivity of hard and soft films showed a significant difference in the activation energy of conductivity and the conductivity at an elevated temperature. The established dependences of the direct current conductivity and the activation energy value of the films on the discharge parameters can be used as diagnostic benchmarks of different types of plasma discharges in a tokamak. Data on the electrical conductivity of the films are analyzed within the framework of the concept of the electronic structure of amorphous non-crystalline materials.  

Sign in / Sign up

Export Citation Format

Share Document