Behavior Of Optical Conductivity Research Articles

Электросопротивление и оптическая проводимость монокристалла антиферромагнитного топологического изолятора MnBi2Te4

The anisotropy of the electrical resistivity and optical properties of the antiferromagnetic topological insulator MnBi2Te4 single crystal has been studied. It is shown that the electrical resistivity of MnBi2Te4 measured perpendicular to the (00l) plane is an order of magnitude higher than the resistivity measured in this plane. The behavior of optical conductivity is qualitatively similar for the cases when light is directed at the surface (00l) and at a surface perpendicular to the plane (00l). It has been shown that the optical spectrum of MnBi2Te4 is formed predominantly by interband transitions of charge carriers.

The effects of spin–orbit coupling on optical properties of electronic Lieb lattice in the presence of magnetic field

In this paper, the optical conductivity of a two-dimensional Lieb lattice that is a line-centered square lattice is investigated in the presence of magnetic field and spin–orbit coupling. Specially, we address the frequency dependence of optical conductivity due to spin–orbit interaction. Using Green’s function approach, the behavior of optical conductivity has been obtained in the context of Kane–Mele model Hamiltonian. In the presence of magnetic field at low spin–orbit coupling strength, optical conductivity includes only Drude weight at zero frequency limit while interband transitions of electrons have no contribution to optical conductivity for each gap parameter below normalized value 0.6. However the increase of spin–orbit coupling strength causes to appear finite frequency peak in optical conductivity. Moreover our results show that optical conductivity increases with temperature for each value of spin–orbit coupling and magnetic field. Also we have studied the effects of magnetic field, electron doping and spin–orbit coupling on temperature dependence of optical conductivity of Lieb monolayer.

Scaling behavior in the optical conductivity of two-dimensional systems of strongly correlated electrons based on the U(1) slave-boson approach to thet−JHamiltonian

The U(1) holon-pair boson theory of Lee and Salk [Phys. Rev. B 64, 052501 (2001)] is applied to investigate the quantum scaling behavior of optical conductivity in the two-dimensional systems of strongly correlated electrons. We examine the role of both the gauge field fluctuations and spin pair excitations on the $\ensuremath{\omega}∕T$ scaling behavior of the optical conductivity. It is shown that the gauge field fluctuations but not the spin pair excitations are responsible for the scaling behavior in the low-frequency region $\ensuremath{\omega}∕T⪡1$. The importance for the contribution of the nodal spinons to the Drude peak is discussed. It is shown that the $\ensuremath{\omega}∕T$ scaling behavior is manifest in the low-frequency region at low hole concentrations close to a critical concentration at which superconductivity arises at $T=0\phantom{\rule{0.3em}{0ex}}\mathrm{K}$.

Anisotropic Optical Conductivity of Nd2-xCexCuO4 Thin Films

Opticcal conductivity spectra $\sigma_1(\omega)$ of Nd2-xCexCuO4 thin films, measured by the reflectance-transmittance method (R-T method) which has been proposed to investigate far-infrared spectroscopy, are investigated based on the anisotropic pairing model. Precise measurements of the frequency-dependent conductivity enable us to examine quantitatively the nature of the superconducting gap through infrared properties in the electron-doped high-Tc superconductors. We show that the behavior of optical conductivity $\sigma_1$ is consistent with the anisotropic superconducting gap and is well explained by the formula for d-wave pairing in the low-energy regime of the far-infrared region. Our results suggest that the electron-doped cuprate superconductors Nd2-xCexCuO4 have nodes in the superconducting gap.

Anomalous Optical Conductivity in the Normal State of HighTcOxides

The optical resistivity due to antiferromagnetic spin fluctuations in two-dimensional metals, as a possible model for high T c oxides, is calculated within the Born approximation and the self-consistent renormalization (SCR) theory for the spin fluctuations. The result is shown to explain the observed anomalous behavior of optical conductivity in YBa 2 Cu 3 O 7 above T c quantitatively.