Possible superlattice formation in high-temperature treated carbonaceous MgB2 at elevated pressure
arXiv:cond-mat/0310312 · doi:10.1016/j.physb.2005.09.042
Abstract
We report indications of a phase transition in carbonaceous MgB2 above 9 GPa at 300 K after stress relaxation by laser heating. The transition was detected using Raman spectroscopy and X-ray diffraction. The observed changes are consistent with a second-order structural transition involving a doubling of the unit cell along c and a reduction of the boron site symmetry. Moreover, the Raman spectra suggest a reduction in electron-phonon coupling in the slightly modified MgB2 structure consistent with the previously proposed topological transition in MgB2. However, further attributes including deviatoric stress, lattice defects, and compositional variation may play an important role in the observed phenomena.
18 pages, 4 figures, 35 references. To appear in Physica B (Available online 9 December 2005)
References in corpus (20)
- Superconductivity of metallic boron in MgB_2
- Beyond Eliashberg superconductivity in MgB2: anharmonicity, two-phonon scattering, and multiple gaps
- Boron Isotope Effect in Superconducting MgB
- Specific Heat of Mg ^{11}B_2
- Phonon dispersion and electron-phonon coupling in MgB_2 and AlB_2
- Giant anharmonicity and non-linear electron-phonon coupling in MgB; A combined first-principles calculations and neutron scattering study
- Pressure-induced alpha-to-omega transition in titanium metal: A systematic study of the effects of uniaxial stress
- Specific heat in the superconducting and normal state (2-300 K, 0-16 Teslas), and magnetic susceptibility of the 38-K superconductor MgB2: evidence for a multicomponent gap
- Evidence for Two Superconducting Gaps in
- Prediction of High Tc Superconductivity in Hole-doped LiBC
- Growth, structure analysis and anisotropic superconducting properties of MgB2 single crystals
- Carbon-substitution effect on the electronic properties of MgB single crystals
- Lattice Properties of MgB2 versus Temperature and Pressure
- Melting of tantalum at high pressure determined by angle dispersive x-ray diffraction in a double-sided laser-heated diamond-anvil cell
- Raman spectrum and lattice parameters of MgB2 as a function of pressure
- Phonons in MgB2 by Polarized Raman Scattering on Single Crystals
- Crystal structure and lattice dynamics of AlB2 under pressure and implications for MgB2
- MgB_2 under pressure: phonon calculations, Raman spectroscopy, and optical reflectance
- Absence of a structural transition up to 40 Gpa in MgB2 and the relevance of magnesium non-stoichiometry
- Raman spectra of MgB2 at high pressure and topological electronic transition