Optic phonons and anisotropic thermal conductivity in hexagonal Ge2Sb2Te5.
作者： Saikat Mukhopadhyay , Lucas Lindsay , David J. Singh
DOI: 10.1038/SREP37076
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摘要: The lattice thermal conductivity (κ) of hexagonal Ge2Sb2Te5 (h-GST) is studied via direct first-principles calculations. We find significant intrinsic anisotropy (κa/κc~2) κ in bulk h-GST, with the dominant contribution to from optic phonons, ~75%. This extremely unusual as acoustic phonon modes are majority heat carriers typical semiconductors and insulators. derives varying bonding along different crystal directions, specifically weak interlayer c-axis, which gives anisotropic dispersions. spectrum h-GST has very dispersive branches higher group velocities a-axis compared flat bands c-axis. large mode contributions low-κ unusual, development fundamental physical understanding these may be critical better conduction other complex layered materials.
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