Theory of thermal fluctuations in two-band superconductors under an essentially homogeneous magnetic field is developed within the framework of the two-band Ginzburg-Landau theory. The fluctuating specific heat is cal...Theory of thermal fluctuations in two-band superconductors under an essentially homogeneous magnetic field is developed within the framework of the two-band Ginzburg-Landau theory. The fluctuating specific heat is calculated by using the optimized self-consistent perturbation approach and the results are applied to analyze the thermodynamic data of the iron-based superconductors Ba（1-x）KxFe2As2 with x -0.4, which have been suggested to have a two-band structure by recent experiments. We estimate the fluctuation strength in this material and find that the specific heat is described well with the Ginzburg number Gi = 4 · 10^-4. The influence of interband coupling strength is investigated and the result of the two-band Gaussian approximation approach is compared.展开更多
In the present theoretical work, superconducting order parameter (∆) and electronic specific heat (C<sub>es</sub>) of SmOFeAs iron pnictide (IP) superconductor has been studied using multiband (M...In the present theoretical work, superconducting order parameter (∆) and electronic specific heat (C<sub>es</sub>) of SmOFeAs iron pnictide (IP) superconductor has been studied using multiband (MB) model of IP superconductors. Attempt has been made to use the MB structure of IP superconductors and expressions for critical temperature (T<sub>c</sub>) and C<sub>es</sub> are obtained, calculations being made for one, two and three bands of SmOFeAs. It has been found that MB results are close to the experimental value of T<sub>c</sub> for this compound. C<sub>es</sub> calculations show jump of 1.5 × 10<sup>-5</sup> eV/atom K, 4 × 10<sup>-5</sup> eV/atom K and 4 × 10<sup>-5</sup> eV/atom K for one, two and three band models respectively. The study brings out the importance of MB structure in IPs, highlighting the fact that increasing the number of bands, increases T<sub>c</sub>. The specific heat jump (∆C) does not correspond to the BCS value, thereby proving that IPs are unconventional in nature.展开更多
Specific heat is a powerful tool to investigate the physical properties of condensed materials.Superconducting state is achieved through the condensation of paired electrons,namely,the Cooper pairs.The condensed Coope...Specific heat is a powerful tool to investigate the physical properties of condensed materials.Superconducting state is achieved through the condensation of paired electrons,namely,the Cooper pairs.The condensed Cooper pairs have lower entropy compared with that of electrons in normal metal,thus specific heat is very useful in detecting the low lying quasiparticle excitations of the superconducting condensate and the pairing symmetry of the superconducting gap.In this brief overview,we will give an introduction to the specific heat investigation of the physical properties of superconductors.We show the data obtained in cuprate and iron based superconductors to reveal the pairing symmetry of the order parameter.展开更多
Recently, systematic investigations on Bi-based superconductors were carried out by means of ultrasonic measurements, thermal analysis, specific heat experiments and X-ray diffraction measurements. It was found for th...Recently, systematic investigations on Bi-based superconductors were carried out by means of ultrasonic measurements, thermal analysis, specific heat experiments and X-ray diffraction measurements. It was found for the first time that a possible structural phase transition occurs near 210 K in these systems. All the samples used were of single phase展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11674007)
文摘Theory of thermal fluctuations in two-band superconductors under an essentially homogeneous magnetic field is developed within the framework of the two-band Ginzburg-Landau theory. The fluctuating specific heat is calculated by using the optimized self-consistent perturbation approach and the results are applied to analyze the thermodynamic data of the iron-based superconductors Ba（1-x）KxFe2As2 with x -0.4, which have been suggested to have a two-band structure by recent experiments. We estimate the fluctuation strength in this material and find that the specific heat is described well with the Ginzburg number Gi = 4 · 10^-4. The influence of interband coupling strength is investigated and the result of the two-band Gaussian approximation approach is compared.
文摘In the present theoretical work, superconducting order parameter (∆) and electronic specific heat (C<sub>es</sub>) of SmOFeAs iron pnictide (IP) superconductor has been studied using multiband (MB) model of IP superconductors. Attempt has been made to use the MB structure of IP superconductors and expressions for critical temperature (T<sub>c</sub>) and C<sub>es</sub> are obtained, calculations being made for one, two and three bands of SmOFeAs. It has been found that MB results are close to the experimental value of T<sub>c</sub> for this compound. C<sub>es</sub> calculations show jump of 1.5 × 10<sup>-5</sup> eV/atom K, 4 × 10<sup>-5</sup> eV/atom K and 4 × 10<sup>-5</sup> eV/atom K for one, two and three band models respectively. The study brings out the importance of MB structure in IPs, highlighting the fact that increasing the number of bands, increases T<sub>c</sub>. The specific heat jump (∆C) does not correspond to the BCS value, thereby proving that IPs are unconventional in nature.
文摘Specific heat is a powerful tool to investigate the physical properties of condensed materials.Superconducting state is achieved through the condensation of paired electrons,namely,the Cooper pairs.The condensed Cooper pairs have lower entropy compared with that of electrons in normal metal,thus specific heat is very useful in detecting the low lying quasiparticle excitations of the superconducting condensate and the pairing symmetry of the superconducting gap.In this brief overview,we will give an introduction to the specific heat investigation of the physical properties of superconductors.We show the data obtained in cuprate and iron based superconductors to reveal the pairing symmetry of the order parameter.
文摘Recently, systematic investigations on Bi-based superconductors were carried out by means of ultrasonic measurements, thermal analysis, specific heat experiments and X-ray diffraction measurements. It was found for the first time that a possible structural phase transition occurs near 210 K in these systems. All the samples used were of single phase
