scholarly journals Self-Consistent Two-Gap Description of MgB2 Superconductor

Symmetry ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1012 ◽  
Author(s):  
Hyunsoo Kim ◽  
Kyuil Cho ◽  
Makariy A. Tanatar ◽  
Valentin Taufour ◽  
Stella K. Kim ◽  
...  
Keyword(s):  
First Principles ◽  
Quantitative Description ◽  
Superfluid Density ◽  
Thermodynamic Quantities ◽  
First Principles Calculations ◽  
Temperature Dependent ◽  
Critical Fields ◽  
Coupling Matrix ◽  
Self Consistent ◽  
Upper Critical Fields

A self-consistent two-gap γ -model is used to quantitatively describe several thermodynamic properties of MgB 2 superconductor. The superconducting coupling matrix, ν i j , was obtained from the fitting of the superfluid density in the entire superconducting temperature range. Using this input, temperature-dependent superconducting gaps, specific heat, and upper critical fields were calculated with no adjustable parameters and compared with the experimental data as well as with the first-principles calculations. The observed agreement between fit and data shows that γ -model provides adequate quantitative description of the two-gap superconductivity in MgB 2 and may serve as a relatively simple and versatile self-consistent description of the thermodynamic quantities in multi-gap superconductors.

scholarly journals The thermal stability of FAPbBr3 nanocrystals from temperature-dependent photoluminescence and first-principles calculations

RSC Advances ◽  
2020 ◽  
Vol 10 (72) ◽  
pp. 44373-44381
Author(s):  
Xiaozhe Wang ◽  
Qi Wang ◽  
Zhijun Chai ◽  
Wenzhi Wu
Keyword(s):  
First Principles ◽  
First Principle ◽  
First Principles Calculations ◽  
Temperature Dependent ◽  
Time Resolved ◽  
First Principle Calculations ◽  
Steady State Time ◽  
Time Resolved Photoluminescence ◽  
Thermal Stability Of ◽  
Temperature Dependent Photoluminescence

The thermal properties of FAPbBr3 perovskite nanocrystals (PNCs) is investigated by use of temperature-dependent steady-state/time-resolved photoluminescence and first-principle calculations.

scholarly journals Extent of Fermi-surface reconstruction in the high-temperature superconductor HgBa2CuO4+δ

2020 ◽  
Vol 117 (18) ◽  
pp. 9782-9786
Author(s):  
Mun K. Chan ◽  
Ross D. McDonald ◽  
B. J. Ramshaw ◽  
Jon B. Betts ◽  
Arkady Shekhter ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Surface Reconstruction ◽  
Field Measurements ◽  
Temperature Dependent ◽  
Crucial Issue ◽  
Critical Fields ◽  
Sign Change ◽  
Underdoped Cuprates ◽  
Upper Critical Fields ◽  
Fermi Surface Reconstruction

High magnetic fields have revealed a surprisingly small Fermi surface in underdoped cuprates, possibly resulting from Fermi-surface reconstruction due to an order parameter that breaks translational symmetry of the crystal lattice. A crucial issue concerns the doping extent of such a state and its relationship to the principal pseudogap and superconducting phases. We employ pulsed magnetic-field measurements on the cuprate HgBa2CuO4+δ to identify signatures of Fermi-surface reconstruction from a sign change of the Hall effect and a peak in the temperature-dependent planar resistivity. We trace the termination of Fermi-surface reconstruction to two hole concentrations where the superconducting upper critical fields are found to be enhanced. One of these points is associated with the pseudogap endpoint near optimal doping. These results connect the Fermi-surface reconstruction to both superconductivity and the pseudogap phenomena.

First-principles Study of the Electronic Structure and Local Moment Interactions in PuAm Alloy

2008 ◽  
Vol 1104 ◽  
Author(s):  
Myung Joon Han ◽  
Xiangang Wan ◽  
Sergej Y Savrasov
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Local Density ◽  
Exchange Interactions ◽  
Kondo Lattice ◽  
First Principles Calculations ◽  
Correlation Effects ◽  
Self Consistent ◽  
5F Electrons ◽  
Zero Moment

AbstractExpected to provide a clue about the origin of zero moment in the bulk phase of Plutonium, Pu1-xAmx alloys have attracted a great attention, in which upon doping the system transforms from the Kondo lattice to the diluted impurity limit. To understand the electronic structure and the magnetic properties of Pu in different crystal environments, we performed fully self-consistent first-principles calculations of the PuAm system based on the local density approximation (LDA) combined with static (LDA+U) and dynamic corrections (LDA+DMFT) for on-site electron correlations. The electronic structure strongly depends on the level of approximation for correlation effects. The exchange interactions between Pu 5f electrons and the Kondo screening strength were estimated and compared, which provide a new insight to Pu magnetism.

Spin-manipulated phonon dynamics during magnetic phase transitions in triangular lattice antiferromagnet CuCr1−xMgxO2 semiconductor films

RSC Advances ◽  
2016 ◽  
Vol 6 (32) ◽  
pp. 27136-27142 ◽  
Author(s):  
Xurui Li ◽  
Junyong Wang ◽  
Jinzhong Zhang ◽  
Yawei Li ◽  
Zhigao Hu ◽  
...  
Keyword(s):  
Phase Transitions ◽  
First Principles ◽  
Magnetic Phase ◽  
Magnetic Phase Transitions ◽  
First Principles Calculations ◽  
Semiconductor Films ◽  
Temperature Dependent ◽  
Phonon Spectra ◽  
Phonon Dynamics ◽  
Triangular Lattice Antiferromagnet

The temperature-dependent phonon spectra and magnetoresistance of CuCr1−xMgxO2 films have been studied, combined with first-principles calculations.

Characterisation of the temperature-dependent M1 to R phase transition in W-doped VO2 nanorod aggregates by Rietveld refinement and theoretical modelling

2020 ◽  
Vol 22 (15) ◽  
pp. 7984-7994
Author(s):  
Lei Miao ◽  
Ying Peng ◽  
Dianhui Wang ◽  
Jihui Liang ◽  
Chaohao Hu ◽  
...  
Keyword(s):  
Rietveld Refinement ◽  
First Principles ◽  
Atomic Scale ◽  
Theoretical Modelling ◽  
First Principles Calculations ◽  
Temperature Dependent ◽  
Macro Scale ◽  
Scale Properties ◽  
W Doping ◽  
Synchrotron Xrd

Synchrotron XRD Rietveld refinement is combined with first-principles calculations to probe the effect of W doping on the IMT mechanism in VO2 nanorods, providing insights into the connection between atomic-scale phenomena and macro-scale properties.

scholarly journals First-principles and CALPHAD-type study of the Ir-Mo and Ir-W systems

2020 ◽  
Vol 56 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Y.-Y. Huang ◽  
B. Wu ◽  
F. Li ◽  
L.-L. Chen ◽  
Z.-X. Deng ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Thermodynamic Property ◽  
Phase Equilibria ◽  
First Principles ◽  
Critical Evaluation ◽  
Intermetallic Phases ◽  
First Principles Calculations ◽  
Property Data ◽  
Self Consistent

This study presents the thermodynamic modeling of the Ir-Mo and Ir-W systems by means of the CALPHAD (CALculation of PHAse Diagrams) approach supported with the first-principles calculations. A critical evaluation of the phase equilibria and the thermodynamic property data in literature was conducted for both systems. Due to the lack of experimental data, the first-principles calculations were applied to obtain the enthalpies of the solid and intermetallic phases. The thermodynamic parameters were assessed using the PARROT module of Thermo-Calc. A set of self-consistent parameters for the Ir-Mo and Ir-W systems was obtained after the optimization. Satisfactory agreement between the calculated results and the experimental data, including phase equilibria and thermodynamic properties was achieved.

scholarly journals Thermodynamic modeling of the In-Sc and In-Y systems supported by first-principles calculations

2018 ◽  
Vol 54 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Z. Hu ◽  
C. Huang ◽  
J. Tu ◽  
Y. Huang ◽  
A. Dong
Keyword(s):  
Intermetallic Compounds ◽  
Thermodynamic Modeling ◽  
First Principles ◽  
Regular Solution Model ◽  
Calphad Method ◽  
Enthalpies Of Formation ◽  
Thermodynamic Optimization ◽  
First Principles Calculations ◽  
Self Consistent ◽  
Good Agreement

Based on an assessment of the phase equilibria and thermodynamic data in the literature, the thermodynamic modeling of the In?Sc and In?Y systems was carried out by means of the calculation of phase diagram (CALPHAD) method supported by first-principles calculations. The solution phases, i.e., liquid, (In), (?Sc), (?Sc), (?Y) and (?Y), were modeled with the substitutional regular solution model. Ten intermetallic compounds, including InSc3, InSc2, In4Sc5, InSc, In2Sc, In3Sc, InY2, InY, In5Y3, and In3Y were described as stoichiometric phases, while In3Y5 was modeled with a sublattice model with respect to its homogeneity range. The enthalpies of formation of the intermetallic compounds at 0 K were computed using firstprinciple calculations and were used as input for the thermodynamic optimization. A set of self-consistent thermodynamic parameters for both the In?Sc and In?Y systems were obtained and the calculated phase diagrams are in good agreement with the experimental data.

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