A three-orbital per site theoretical model study is attempted to analyze the nature of specific heat in iron-based superconductors. Based on recent experimental data, it is found that the five Fe 3d orbitals, Hund's coupling, and intra- and inter-electron orbital correlations play a significant role in the electronic properties of these systems. Thus, in the present work, a model Hamiltonian containing hopping between orbitals, Hund's coupling, and intra- and inter-orbital Coulomb interactions is employed for iron pnictide. Employing Green's function technique within Bardeen–Cooper–Schrieffer (BCS) mean-field approximation, expressions of superconducting energy gap parameter and quasiparticle energies are obtained. Considering these parameters, specific heat is calculated and its variation with temperature and other parameters of the model Hamiltonian is analyzed. Also, a pseudogap (PG) parameter, arising out of multi-orbitals’ Hund's coupling, as supported by angle-resolved photoemission spectroscopy and scanning tunneling microscopy experiments, is introduced. The expression of specific heat is numerically analyzed to pinpoint its variation below and above the transition temperature (T _c). Self-consistent numerical analysis of the specific heat jump as a function of multi-orbital hopping, electron interactions, and Hund's coupling in terms of PG parameter is shown in detail. Finally, the outcomes are compared with recent theoretical and experimental data available on specific heat variations in iron superconductors like LaOFeAs system.

中文翻译：

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多轨道和洪德耦合诱导的赝能隙对铁-磷族高温超导体中比热跃变的影响

尝试进行每位点三轨道理论模型研究，以分析铁基超导体中比热的性质。根据最近的实验数据，发现 5 个 Fe 3 d轨道、洪德耦合以及电子内和电子间轨道相关性在这些系统的电子特性中起着重要作用。因此，在目前的工作中，包含轨道间跳跃、洪德耦合以及轨道内和轨道间库仑相互作用的模型哈密顿量用于铁 pnictide。在 Bardeen-Cooper-Schrieffer (BCS) 平均场近似中采用格林函数技术，获得了超导能隙参数和准粒子能量的表达式。考虑到这些参数，计算比热并分析其随温度和模型哈密顿量其他参数的变化。此外，由多轨道的 Hund 耦合产生的赝能隙 (PG) 参数，在角分辨光电子能谱和扫描隧道显微镜实验的支持下，介绍了这一点。对比热的表达式进行数值分析，以查明其在转变温度以下和以上的变化（Tc _）。详细显示了作为多轨道跳跃、电子相互作用和洪德耦合在 PG 参数方面的函数的比热跳跃的自洽数值分析。最后，将结果与最近可用的关于铁超导体（如 LaOFeAs 系统）的比热变化的理论和实验数据进行比较。