English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Optical measurements and band structure calculations are reported on 3D Diracmaterials. The electronic properties associated with the Dirac cone areidentified in the reflectivity spectra of Cd$_3$As$_2$ and Na$_3$Bi singlecrystals. In Na$_3$Bi, the plasma edge is found to be strongly temperaturedependent due to thermally excited free carriers in the Dirac cone. The thermalbehavior provides an estimate of the Fermi level $E_F=25$ meV and the z-axisFermi velocity $v_z = 0.3 \text{ eV} \AA$ associated with the heavy bismuthDirac band. At high energies above the $\Gamma$-point Lifshitz gap energy, afrequency and temperature independent $\epsilon_2$ indicative of Dirac coneinterband transitions translates into an ab-plane Fermi velocity of $3 \text{eV} \AA$. The observed number of IR phonons rules out the$\text{P}6_3\text{/mmc}$ space group symmetry but is consistent with the$\text{P}\bar{3}\text{c}1$ candidate symmetry. A plasmaron excitation isdiscovered near the plasmon energy that persists over a broad range oftemperature. The optical signature of the large joint density of states arisingfrom saddle points at $\Gamma$ is strongly suppressed in Na$_3$Bi consistentwith band structure calculations that show the dipole transition matrixelements to be weak due to the very small s-orbital character of the Diracbands. In Cd$_3$As$_2$, a distinctive peak in reflectivity due to thelogarithmic divergence in $\epsilon_1$ expected at the onset of Dirac coneinterband transitions is identified. The center frequency of the peak shiftswith temperature quantitatively consistent with a linear dispersion and acarrier density of $n=1.3\times10^{17}\text{ cm}^{-3}$. The peak width gives ameasure of the Fermi velocity anisotropy of $10\%$, indicating a nearlyspherical Fermi surface. The lineshape gives an upper bound estimate of 7 meVfor the potential fluctuation energy scale.

3D Dirac cone carrier dynamics in Na3Bi and Cd3As2