Anisotropic Energy‐Gap Measurements on Superconducting Niobium Single Crystals by Tunneling

1968 ◽  
Vol 39 (3) ◽  
pp. 1721-1727 ◽  
Author(s):  
M. L. A. MacVicar ◽  
R. M. Rose
Keyword(s):  
Single Crystals ◽  
Energy Gap ◽  
Anisotropic Energy

scholarly journals Anisotropic energy gap of low-frequency AFMR mode in Fe x Ga 1-x BO3 single crystals

2019 ◽  
Vol 1400 ◽  
pp. 044016 ◽  
Author(s):  
Yu Mogilenec ◽  
K Seleznyova ◽  
M Strugatsky ◽  
S Yagupov ◽  
A Drovosekov ◽  
...  
Keyword(s):  
Single Crystals ◽  
Energy Gap ◽  
Low Frequency ◽  
Anisotropic Energy

scholarly journals Estimation of optical parameters of silicon single crystals with different orientations

2019 ◽  
Vol 37 (1) ◽  
pp. 65-70
Author(s):  
M.M. El-Nahass ◽  
H.A.M. Ali
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Single Crystals ◽  
Energy Gap ◽  
Optical Parameters ◽  
Dispersion Energy ◽  
High Frequency Dielectric Constant ◽  
Single Oscillator Model ◽  
Indirect Allowed Transition ◽  
Single Oscillator

AbstractOptical properties of Si single crystals with different orientations (1 0 0) and (1 1 1) were investigated using spectrophotometric measurements in a spectral range of 200 nm to 2500 nm. The data of optical absorption revealed an indirect allowed transition with energy gap of 1.1 ± 0.025 eV. An anomalous dispersion in refractive index. The normal dispersion of the refractive index was discussed according to Wemple-DiDomenico single oscillator model. The oscillator energy Eo, dispersion energy Ed, high frequency dielectric constant ∈∞, lattice dielectric constant ∈L and electronic polarizability αe were estimated. The real ∈1 and imaginary ∈2 parts of dielectric constant were also determined.

Preparation and Characterisation of (ZnTe)x(CdSe)1−x Single Crystals

1989 ◽  
Vol 161 ◽  
Author(s):  
V.K. Madhu Smitha Rani ◽  
R.P. Vijayalakshmi ◽  
D. Raja Reddy ◽  
B.K. Reddy
Keyword(s):  
Chemical Analysis ◽  
Single Crystals ◽  
Entire Range ◽  
Energy Gap ◽  
Spectral Response ◽  
Alloy System ◽  
Crystalline Form ◽  
Reflection Spectra ◽  
Alloy Material ◽  
P Type

ABSTRACTThe titlematerial is one of the least studied among the II-VI alloy systems. So far it has not been possible to prepare ZnTe in n-type and CdSe in p-type with appreciable conductivities. Moreover ZnTe crystallises in zincblende whereas CdSe crystallises in wurtzite structure. Because of the varied nature of the end compounds, an attempt has been made to prepare single crystals of (ZnTe)x(CdSe)1−x in the entire range of ‘x’. The alloy material in the entire range Xof composition in the single crystalline form was grown by a modified Piper-Plich method. The grown crystals of this alloy system have been subjected to chemical analysis. DTA and DTG studies carried out on these alloys did not show any phasec transitions. However two exothermic peaks associated with increase in mass were noticed. This has been attributed to oxidation effects of Se/Te or Cd/Zn. XRD data though showed some regularity near end compositions there is still some ambiguity for the middle compositions. Energy gap obtained from reflection spectra and also photocurrent spectral response showed bowing. However, there is a marked different feature at one of the end regions. The growth and the results of all the above mentioned investigations are presented and discussed in this paper.

scholarly journals Energy gap evolution across the superconductivity dome in single crystals of (Ba1−xKx)Fe2As2

2016 ◽  
Vol 2 (9) ◽  
pp. e1600807 ◽  
Author(s):  
Kyuil Cho ◽  
Marcin Kończykowski ◽  
Serafim Teknowijoyo ◽  
Makariy A. Tanatar ◽  
Yong Liu ◽  
...  
Keyword(s):  
Single Crystals ◽  
Abrupt Change ◽  
Energy Gap ◽  
Superconducting Transition ◽  
London Penetration Depth ◽  
Wave State ◽  
Iron Based Superconductors ◽  
Optimal Doping ◽  
Gap Anisotropy ◽  
Materials Research

The mechanism of unconventional superconductivity in iron-based superconductors (IBSs) is one of the most intriguing questions in current materials research. Among non-oxide IBSs, (Ba1−xKx)Fe2As2has been intensively studied because of its high superconducting transition temperature and fascinating evolution of the superconducting gap structure from being fully isotropic at optimal doping (x≈ 0.4) to becoming nodal atx> 0.8. Although this marked evolution was identified in several independent experiments, there are no details of the gap evolution to date because of the lack of high-quality single crystals covering the entire K-doping range of the superconducting dome. We conducted a systematic study of the London penetration depth, λ(T), across the full phase diagram for different concentrations of point-like defects introduced by 2.5-MeV electron irradiation. Fitting the low-temperature variation with the power law, Δλ ~Tn, we find that the exponentnis the highest and theTcsuppression rate with disorder is the smallest at optimal doping, and they evolve with doping being away from optimal, which is consistent with increasing gap anisotropy, including an abrupt change aroundx≃ 0.8, indicating the onset of nodal behavior. Our analysis using a self-consistentt-matrix approach suggests the ubiquitous and robust nature ofs±pairing in IBSs and argues against a previously suggested transition to ad-wave state nearx= 1 in this system.

Luminescence, transmission and width of the energy gap of CdTe single crystals

Physica ◽  
1956 ◽  
Vol 22 (1-5) ◽  
pp. 338-342 ◽  
Author(s):  
C.Z. Van Doorn ◽  
D. De Nobel
Keyword(s):  
Single Crystals ◽  
Energy Gap

No-Phonon and Phonon-Assisted Indirect Transitions in Si1−xGex Single Crystals

1996 ◽  
Vol 450 ◽  
Author(s):  
A. Gerhardt
Keyword(s):  
Single Crystals ◽  
Absorption Edge ◽  
Energy Gap ◽  
Differential Method ◽  
Composition Analysis ◽  
Calibration Function ◽  
Absorption Properties ◽  
Transmission Measurements ◽  
Threshold Energies ◽  
Phonon Transition

ABSTRACTThe absorption properties of high quality bulk Si1−xGex single crystals (0 ≤ × ≤ 0.16) are studied. Transmission measurements were performed at the indirect absorption edge. The shape of the absorption edge is characterized by structures attributed to the onset of no-phonon and phonon-assisted indirect optical transitions. Threshold energies have been determined using a differential method. A corrected calibration function for the dependence of the excitonic energy gap on composition is presented for the compositions, where x ranges from 0 to 0.16. The presented calibration function can be used for the composition analysis by an optical method. The analysis is independent of absolute transmission values.A simulation of the absorption spectra by calculations based on second order perturbation theory was used to fit the experimental data This procedure allows to estimate the oscillator strength of the no-phonon transition in dependence on x.

OPTICAL PROPERTIES OF UNDOPED AND Ni-DOPED SbSBr AND BiSBr SINGLE CRYSTALS

1995 ◽  
Vol 09 (03n04) ◽  
pp. 229-235
Author(s):  
MOON-SEOG JIN ◽  
HO-JUN SONG ◽  
YONG-GEUN KIM ◽  
HYUNG-GON KIM ◽  
JEONG-DAE KOH ◽  
...  
Keyword(s):  
Single Crystals ◽  
Energy Gap ◽  
Energy Levels ◽  
Bridgman Technique ◽  
Optical Energy Gap ◽  
Impurity Site ◽  
First Order ◽  
Electron Transitions ◽  
First Order Phase Transition ◽  
First Order Phase

SbSBr, BiSBr, SbSBr:Ni, and BiSBr:Ni single crystals were grown by the Bridgman technique. The grown single crystals crystallized in an orthorhombic structure and have an indirect band structure. The temperature dependence of their optical energy gap shows an anomalous property at the first order phase transition temperature and at the second order one. Nickel doped as an impurity site at the T d symmetry point in the host single crystals as Ni 2+ ion. The impurity optical absorption peaks appeared by the electron transitions between the energy levels of these ions.

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