scholarly journals Impurity scattering rate and coherence factor in vortex core of sign-reversings-wave superconductors

2010 ◽  
Vol 82 (17) ◽  
Author(s):  
Yuki Nagai ◽  
Yusuke Kato
Keyword(s):  
Vortex Core ◽  
Impurity Scattering ◽  
Scattering Rate ◽  
Coherence Factor

scholarly journals Relation of Superconducting Pairing Symmetry and Non-Magnetic Impurity Effects in Vortex States

Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 175
Author(s):  
Yasuaki Sera ◽  
Takahiro Ueda ◽  
Hiroto Adachi ◽  
Masanori Ichioka
Keyword(s):  
Vortex Core ◽  
Magnetic Impurity ◽  
Impurity Scattering ◽  
Pairing Symmetry ◽  
Impurity Effects ◽  
Vortex States ◽  
Scattering Rate ◽  
Pairing Function ◽  
Sign Change ◽  
Anisotropic Superconductors

Non-magnetic impurity scattering effects on the vortex core states are theoretically studied to clarify the contributions from the sign-change of the pairing function in anisotropic superconductors. The vortex states are calculated by the Eilenberger theory in superconductors with p x -wave pairing symmetry, as well as the corresponding anisotropic s-wave symmetry. From the spatial structure of the pair potential and the local electronic states around a vortex, we examine the differences between anisotropic superconductors with and without sign-change of the pairing function, and estimate how twofold symmetric vortex core images change with increasing the impurity scattering rate both in the Born and the unitary limits. We found that twofold symmetric vortex core image of zero-energy local density of states changes the orientation of the twofold symmetry with increasing the scattering rate when the sign change occurs in the pairing function. Without the sign change, the vortex core shape reduces to circular one with approaching dirty cases. These results of the impurity effects are valuable for identifying the pairing symmetry by observation of the vortex core image by the STM observation.

scholarly journals Effect of Born and unitary impurity scattering on the Kramer–Pesch shrinkage of a vortex core in an s-wave superconductor

2013 ◽  
Vol 484 ◽  
pp. 69-73 ◽  
Author(s):  
Nobuhiko Hayashi ◽  
Yoichi Higashi ◽  
Noriyuki Nakai ◽  
Hisataka Suematsu
Keyword(s):  
Vortex Core ◽  
Impurity Scattering ◽  
S Wave

Comparative Analysis of λ≈9µm GaAs/AlGaAs Quantum Cascade Lasers with Different Injector Doping

2006 ◽  
Vol 518 ◽  
pp. 29-34
Author(s):  
D. Indjin ◽  
S. Höfling ◽  
A. Mirčetić ◽  
V.D. Jovanović ◽  
J. Radovanović ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Quantum Cascade Lasers ◽  
Optical Power ◽  
Impurity Scattering ◽  
Resonance Structure ◽  
Quantum Cascade ◽  
Scattering Rate ◽  
Current Saturation ◽  
Single Temperature ◽  
Cascade Lasers

An experimental and theoretical comparative analysis of the output characteristics of λ ≈ 9m GaAs/Al0.45Ga0.55As quantum cascade lasers based on single and double phonon resonance depopulation mechanisms were presented. The layer structures were grown with solid source molecular beam epitaxy and consist of 48 or 36 active stages embedded in a symmetrical plasmon enhanced waveguide. From the wafers, ridge waveguide lasers were fabricated by optical lithography and dry etching. The theoretical model is based on a fully non-equilibrium Schrödinger- Poisson self-consistent analysis of the coupled scattering rate and single-temperature energy balance equations, taking all relevant electron-LO phonon, electron-electron and electron-ionised impurity scattering processes into account. Single phonon resonance devices exhibit clear current saturation, simultaneously with a decrease of the optical power. In the moderate doping regime, a quasi-linear dependence of both the threshold and saturation current densities on injector doping, were measured, in a very good agreement with theoretical predictions. Double phonon resonance lasers exhibit ‘saturation’ mechanism evident from their decrease in optical power, but without pronounced current saturation. Previously reported saturation of the ‘maximal’ current under higher injector doping in single phonon resonance lasers, is also observed in the double phonon resonance structure for injector sheet doping above 8x1011cm-2.

Temperature Dependence Electron-Impurity Scattering Rate in Doped Bilayer Graphene

2013 ◽  
Vol 665 ◽  
pp. 154-158
Author(s):  
Digish K. Patel ◽  
K.N. Vyas ◽  
A.C. Sharma
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Single Layer ◽  
Impurity Scattering ◽  
Temperature Limit ◽  
Bilayer Graphene ◽  
Particle Energy ◽  
Experimental Result ◽  
High Temperature Limit ◽  
Scattering Rate

Apart from its promising new material for technological innovations and applications, graphene offers a new and novel physics. In recent past, both single layer and bilayer Graphene have extensively been studied. Properties of Graphene sharply differ from that of 2DEG observed in doped semiconductor heterostructures. One of the important properties requisite for device making is charge transport. It has been suggested that considering a scattering mechanism based on screened charged impurities, one can obtain from a Boltzmann equation approach a conductivity that agrees with the experimental result on graphene. In this paper, we present a calculation of electron-impurity scattering rate, as a function of quasi particle energy ε measured from Fermi energy εf, in doped bilayer graphene for both high temperature TTf and low temperature TTf regimes. In the low temperature limit, we observe dip at normalized energy y=1.0, which is absent in the high temperature limit. Our numerical calculation shows that scattering rate remains almost constant with temperature in both regimes.

ELECTRON-IMPURITY SCATTERING IN DOPED SINGLE LAYER GRAPHENE

2013 ◽  
Vol 27 (05) ◽  
pp. 1350033
Author(s):  
DIGISH K. PATEL ◽  
A. C. SHARMA ◽  
S. S. Z. ASHRAF
Keyword(s):  
Fermi Energy ◽  
Transport Theory ◽  
Single Layer ◽  
Impurity Scattering ◽  
Single Layer Graphene ◽  
Boltzmann Transport ◽  
Layer Graphene ◽  
Scattering Rate ◽  
Boltzmann Transport Theory ◽  
Dimensional Electron Gas

We calculated electron-impurity scattering rate (ℏ/τ) as a function of quasiparticle energy (ε) for doped single layer graphene (SLG), bilayer graphene (BLG) and two-dimensional electron gas (2DEG) at zero temperature. (ℏ/τ) of SLG has been computed analytically as well as numerically. Computed results show that ℏ/τ of SLG; (a) tends to zero at ε = 0 and, (b) it exhibits peak at ≈1.6εf, where εf is Fermi energy. Contrary to this, ℏ/τ of 2DEG and BLG show their maximum values at ε = 0 and decline thereafter on increasing ε to attain a minimum at around ε equal to Fermi energy. We thus find that ℏ/τ versus ε of SLG displays an entirely different behavior than that of BLG and 2DEG, suggesting that electron-impurity scattering process in SLG sharply differs from those in BLG and 2DEG. Further, computed ℏ/τ of SLG exhibits a large variation in its magnitude over the energy range of 0 ≤ ε ≤ 3εf. Estimation of resistivity within Boltzmann transport theory involves an scattering rate averaged over all possible values of ε. It can therefore be inferred that the computation of resistivity with the use of ℏ/τ at ε = εf for comparing the computed results with experimental data can be highly misleading. Scattering rates of SLG, BLG and 2DEG are found increasing on enhancing the impurity concentration.

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