We measured reflectivity spectra of polycrystalline Mg1-xB2 samples, which show a metal-insulator transition with x. After performing the Kramers-Kronig analysis, the obtained optical conductivity spectra σ(ω) of MgB2 show a narrow Drude peak in the far-infrared region and a broad peak in the mid-infrared region. As x increases, the spectral weight of the Drude peak is strongly suppressed and that of the broad peak becomes enhanced a little. The existence of the broad mid-infrared peak in the insulating sample suggests that this peak might not be related to the free carriers in MgB2. In the far-infrared region, we also observe that the low energy dielectric constant of Mg1-xB2 diverges near the metal-insulator phase boundary (i.e. x=0.08). This result implies the possibility of a phase separation and a percolative metal-insulator transition in Mg1-xB2.
|Number of pages||5|
|Journal||Solid State Communications|
|State||Published - Apr 2003|
Bibliographical noteFunding Information:
This work was supported by the Ministry of Science and Technology through the Creative Research Initiative Program, and also by the Korea Science and Engineering Foundation through the CSCMR at Seoul National University.
- A. Superconductors
- D. Optical properties
- E. Light absorption and reflection
ASJC Scopus subject areas
- Chemistry (all)
- Condensed Matter Physics
- Materials Chemistry