arXiv subjects

H. -T. S. Lihn

Publications and source records attributed to H. -T. S. Lihn.

4 recordsLinked to original sources

arXiv1996

Composite vortex model of the electrodynamics of high-$T_c$ superconductor

We propose a phenomenological model of vortex dynamics in which the vortex is taken as a composite object made of two components: the vortex current which is massless and driven by the Lorentz force, and the vortex core which is massive and driven by the Magnus force. By combining the characteristics of the Gittleman-Rosenblum model (Phys. Rev. Lett. {\bf 16}, 734 (1966)) and Hsu's theory of vortex dynamics (Physica {\bf C 213},305 (1993)), the model provides a good description of recent far infrared measurements of the magneto-conductivity tensor of superconducting YBa$_2$Cu$_3$O$_{7-δ}$ films from 5 cm$^{-1}$ to 200 cm$^{-1}$.

cond-mat↗

arXiv1996

Measurement of the Far Infrared Magneto-Conductivity Tensor of Superconducting YBa$_2$Cu$_3$O$_{7-δ}$ Thin Films

We report measurements of the far infrared transmission of superconducting YBa$_2$Cu$_3$O$_{7-δ}$ thin films from 5 cm$^{-1}$ to 200 cm$^{-1}$ in fields up to 14$T$. A Kramers-Kronig analysis of the magneto-transmission spectrum yields the magneto-conductivity tensor. The result shows that the magneto-conductivity of YBa$_2$Cu$_3$O$_{7-δ}$ is dominated by three terms: a London term, a low frequency Lorentzian ($ω_1\approx $ 3 cm$% ^{-1}$) of width $Γ_1=$ 10 cm$^{-1}$ and a finite frequency Lorentzian of width $Γ_2=$ 17 cm$^{-1}$ at $ω_2=$ 24 cm$^{-1}$ in the hole cyclotron resonance active mode of circular polarization.\\

cond-mat↗

arXiv1995

Grain Boundary Induced Magneto-Far Infrared Resonances in Superconducting YBa$_2$Cu$_3$O$_{7-δ}$ Thin Films

Spectral features induced by 45$^{\circ }$ in-plane misoriented grains have been observed in the far infrared magneto-transmission of YBa$_2$Cu$_3$O$% _{7-δ}$ thin films. Two strong dispersive features are found at 80 and 160 $cm^{-1}$ and a weaker one at 116 $cm^{-1}$. The data can be well represented by Lorentzian oscillator contributions to the conductivity. Several possible interpretations are discussed. We conclude that the resonances are due to vortex core excitations.

cond-mat↗

arXiv1993

Magneto-Optics of type-II superconductors

The magneto-optical activity of superconducting ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7}$ observed by Karrai {\it et al.} is not present in many commonly employed models of vortex dynamics. Here we propose a simple, unifying picture for the frequency dependent magneto-optic response of type-II superconductors at low temperatures. We bring together Kohn's theorem, vortex core excitations, and vortex pinning and damping into a single expression for the conductivity tensor. The theory describes magneto-optical activity observed in infrared transmission measurements of thin films of ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7}$.

cond-mat↗