Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “LaAlSi”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

2 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Anisotropic Fano resonance in the Weyl semimetal candidate LaAlSi

Topological Weyl semimetal (WSM) is a solid-state realization of chiral Weyl fermions, whose phonon behaviors provide in-depth knowledge of their electronic properties. In this work, anisotropic Fano resonance is observed in a type-II WSM candidate LaAlSi by polarized Raman spectroscopy. The asymmetric line shape occurs for the $B^2_1$ phonon mode of LaAlSi only for 488- and 532-nm laser excitations but not for 364-, 633-, and 785-nm excitations, suggesting the excitation selectivity. The asymmetry, frequency, and linewidth of the $B^2_1$ phonon mode, along with the spectral background, all show fourfold rotational symmetry as a function of the polarization angle in the polarized Raman spectra. While the shift of Raman frequency in a metal or semimetal is typically attributed to Kohn anomaly, here we show that the anisotropic frequency shift in LaAlSi cannot be explained by the effect of Kohn anomaly, but potentially by the anisotropic scattering background of Fano resonance. Origins of the excitation-energy dependence and anisotropic behavior of the Fano resonance are discussed by the first-principles calculated electronic band structure and phonon dispersion.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on LaAlSi by Materials Project

AlSiLa is hexagonal omega structure-derived structured and crystallizes in the tetragonal I4_1md space group. The structure is three-dimensional. La is bonded to six Al and six Si atoms to form a mixture of edge and face-sharing LaAl6Si6 cuboctahedra. There are two shorter (3.27 Å) and four longer (3.30 Å) La–Al bond lengths. There are two shorter (3.27 Å) and four longer (3.30 Å) La–Si bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a distorted trigonal planar geometry to six equivalent La and three Si atoms. There are one shorter (2.46 Å) and two longer (2.49 Å) Al–Si bond lengths. In the second Al site, Al is bonded in a distorted trigonal planar geometry to six equivalent La and three Si atoms. There are one shorter (2.46 Å) and two longer (2.49 Å) Al–Si bond lengths. In the third Al site, Al is bonded in a distorted trigonal planar geometry to six equivalent La and three Si atoms. There are two shorter (3.27 Å) and four longer (3.30 Å) Al–La bond lengths. There are one shorter (2.46 Å) and two longer (2.49 Å) Al–Si bond lengths. There are four inequivalent Si sites. In the first Si site, Si is bonded in a distorted trigonal planar geometry to six equivalent La and three Al atoms. The Si–Al bond length is 2.46 Å. In the second Si site, Si is bonded in a distorted trigonal planar geometry to six equivalent La and three equivalent Al atoms. In the third Si site, Si is bonded in a distorted trigonal planar geometry to six equivalent La and three Al atoms. There are two shorter (3.27 Å) and four longer (3.30 Å) Si–La bond lengths. In the fourth Si site, Si is bonded in a distorted trigonal planar geometry to six equivalent La and three Al atoms. There are two shorter (3.27 Å) and four longer (3.30 Å) Si–La bond lengths.

36 MATERIALS SCIENCE↗