Optical properties and electronic structure of ZrB${}_{12}$

Abstract

We report optical (6 meV - 4 eV) properties of a boride superconductor ZrB${}_{12}$ ($T_c$ = 6 K) in the normal state from 20 to 300 K measured on high-quality single crystals by a combination of reflectivity and ellipsometry. The Drude plasma frequency and interband optical conductivity calculated by self-consistent full-potential LMTO method agree well with experimental data. The Eliashberg function ${\alpha }_{tr}^{2}F(\omega )$ extracted from optical spectra features two peaks at about 25 and 80 meV, in agreement with specific heat data. The total coupling constant is ${\lambda }_{tr}=1.0\pm 0.35$. The low energy peak presumably corresponds to the displacement mode of Zr inside $B_{24}$ cages, while the second one involves largely boron atoms. In addition to the usual narrowing of the Drude peak with cooling down, we observe an unexpected removal of about 10 % of the Drude spectral weight which is partially transferred to the region of the lowest-energy interband transition ($\sim$ 1 eV). This effect may be caused by the delocalization of the metal ion from the center of the $B_{24}$ cluster.

References in corpus (7)

• Superconductivity of metallic boron in MgB_2
• Kramers-Kronig constrained variational analysis of optical spectra
• Specific heat, magnetic susceptibility, resistivity and thermal expansion of the superconductor ZrB12
• Extracting the electron--boson spectral function ${\alpha }^2$F($\omega$) from infrared and photoemission data using inverse theory
• Is ZrB12 two gap superconductor?
• Tunneling and Magnetic Characteristics of Superconducting ZrB${}_{12}$ Single Crystals
• Anomalous electron-phonon coupling probed on the surface of ZrB${}_{12}$ superconductor

Cited by in corpus (6)

• On the importance of the electron-phonon coupling function on the superconducting transition temperature in dodecaboride superconductors: A comparison of LuB12 with ZrB12
• Discovery of superconductivity in technetium-borides at moderate pressures
• Inhomogeneous superconductivity in LuxZr1-xB12 dodecaborides with dynamic charge stripes
• Anisotropic superconductivity in ZrB${}_{12}$ near critical Bogomolnyi point
• Observation of a crossover from nodal to gapped superconductivity in Lu${}_x$Zr${}_{1-x}$B${}_{12}$
• Anomaly in the electronic structure of a BCS superconductor, ZrB(12)