Related papers: Ultralow-dissipative conductivity by Dirac fermion…
We have measured the electrodynamic properties of Y_{1-x}Pr_xBa_2Cu_3O_7 single crystal thin films as a function of temperature using coherent THz-time-domain spectroscopy. We obtain directly the complex conductivity…
We have measured the reflectivity spectra of the iron based superconductor LiFeAs (Tc = 17.6 K) in the temperature range from 4 to 300 K. In the superconducting state (T < Tc), the clear opening of the optical absorption gap was observed…
The in-plane resistivity $\rho$ and thermal conductivity $\kappa$ of FeAs-based superconductor KFe$_2$As$_2$ single crystal were measured down to 50 mK. We observe non-Fermi-liquid behavior $\rho(T) \sim T^{1.5}$ at $H_{c_2}$ = 5 T, and the…
The results of infrared reflectivity measurements for the iron-based high-temperature superconductor Ba(Fe0.9Co0.1)2As2 are reported. The reflectivity is found to be close to unity at frequencies w lower than 2Delta/h (2Delta is the…
Significant manifestation of interplay of superconductivity and charge density wave, spin density wave or magnetism is dome-like variation in superconducting critical temperature (Tc) for cuprate, iron-based and heavy Fermion…
The anomalous thermal conductivity in spin chains observed in experiments is studied for the low temperature regime. In the effective dynamics with most realistic perturbations, the so-called Umklapp terms is irrelevant to reduce mean free…
An unexpected insensitivity of the Fermi surface to impurity scattering is found in Ru substituted BaFe$_2$As$_2$ from first-principles theory, offering a natural explanation of the unusual resilience of transport and superconductivity to a…
We study charge and heat transport in normal-metal/superconductor (NS) hybrid junction, based on a tilted anisotropic Dirac material. Using the extended Blonder-Tinkham-Klapwijk formalism, the conductance spectra of NS borophane, a…
The nature of superconductivity in BiS$_2$-based superconductors has been controversial while ab-initio calculations proposed this system in close proximity to a charge-density-wave (CDW) phase. Using high-energy high-flux X-ray…
We develop a finite temperature mean field theory in the path integral picture for an extremely dilute system of interacting Fermions in a plane. In the limit of short ranged interactions, the system is shown to undergo a phase transition…
We successfully synthesized the BaPt$_2$As$_2$ single crystals and studied their structural and physical properties at low temperatures. BaPt$_2$As$_2$ crystallizes in the CaBe$_2$Ge$_2$-type tetragonal structure (P4/nmm) at room…
We studied the behavior of nontrivial Dirac fermion states in an antiferromagnetic metal SmBi using angle-resolved photoemission spectroscopy (ARPES). The experimental results exhibit multiple Fermi pockets around $\overline{\Gamma}$ and…
Optical reflectance R(w) of a pressure-induced superconductor SrFe2As2 has been measured under external pressure to 6 GPa and at temperatures to 8 K. Optical conductivity s(w) has been derived from the measured R(w). At ambient pressure, in…
The dynamic conductivity $\sigma(\omega)$ of strongly correlated electrons in a symmetry broken phase is investigated in the present work. The model considered consists of spinless fermions with repulsive interaction on a simple cubic…
Quantum transitions in Fe-based systems are believed to involve spin, charge and nematic fluctuations. Complex structural phase diagram in these materials often emphasizes importance of covalency in their exotic properties, which is…
Since the discovery of graphene, layered materials have attracted extensive interests owing to their unique electronic and optical characteristics. Among them, Dirac semimetal, one of the most appealing categories, has been a long-sought…
We study the interplay between Dirac and Schr\"odinger fermions in the polarization properties of a two-dimensional electron gas (2DEG). Specifically, we analyze the low-energy sector of narrow-gap semiconductors described by a two-band…
We theoretically study intrinsic superconductivity in doped Dirac semimetals. Dirac semimetals host bulk Dirac points, which are formed by doubly degenerate bands, so the Hamiltonian is described by a $4 \times 4$ matrix and six types of…
Since the discovery of high-temperature superconductivity in the cuprates a theoretical understanding of their phase diagram has remained one of the major outstanding problems in condensed matter physics. Here we propose an effective…
Two-dimensional Graphene is fascinating because of its unique electronic properties. From a fundamental perspective, one among them is the geometric phase structure near the Dirac points in the Brillouin zone, owing to the SU(2) nature of…