arXiv subjects

J. Y. Son

Publications and source records attributed to J. Y. Son.

2 recordsLinked to original sources

arXiv2006

Infrared Hall conductivity of Na$_{0.7}$CoO$_2$

We report infrared Hall conductivity $σ_{xy}(ω)$ of Na$_{0.7}$CoO$_2$ thin films determined from Faraday rotation angle $θ_{F}$ measurements. $σ_{xy}(ω)$ exhibits two types of hole conduction, Drude and incoherent carriers. The coherent Drude carrier shows a large renormalized mass and Fermi liquid-like behavior of Hall scattering rate, $γ_{H} \sim aT^{2}$. The spectral weight is suppressed and disappears at T = 120K. The incoherent carrier response is centered at mid-IR frequency and shifts to lower energy with increasing T. Infrared Hall constant is positive and almost independent of temperature in sharp contrast with the dc-Hall constant.

cond-mat.str-el↗

arXiv2005

Kinetically-controlled thin-film growth of layered $β$- and $γ-$Na$_{x}$CoO$_{2}$ cobaltate

We report growth characteristics of epitaxial $β$-Na$_{0.6}$CoO$_{2}$ and $γ$-Na$_{0.7}$CoO$_{2}$ thin films on (001) sapphire substrates grown by pulsed-laser deposition. Reduction of deposition rate could change structure of Na$_{x}$CoO$_{2}$ thin film from $β$-phase with island growth mode to $γ$-phase with layer-by-layer growth mode. The $γ$-Na$_{0.7}$CoO$_{2}$ thin film exhibits spiral surface growth with multiterraced islands and highly crystallized texture compared to that of the $β$-Na$_{0.6}$CoO$_{2}$ thin film. This heterogeneous epitaxial film growth can give opportunity of strain effect of physical properties and growth dynamics of Na$_{x}$CoO$_{2}$ as well as subtle nature of structural change.

cond-mat.mtrl-sci↗