Empirical electron-phonon coupling constants and anisotropic electrical resistivity in hcp metals
- Department of Physics, State University of New York, Stony Brook, New York 11794-3800 (US)
- Complex Systems Theory Branch, Naval Research Laboratory, Washington, D.C. 20375-5000
The Fermi-surface density of states {ital N}(0) and Drude-plasma-frequency tensor ({Omega}{sub {ital p}}{sup 2}){sub {alpha}{beta}} =4{pi}{ital e}{sup 2}N(0){l angle}v{sub {alpha}}v{sub {beta}}{r angle} are calculated for 14 metallic elements with hcp structures. By comparison with measured anisotropic resistivity components {rho}{sub {perpendicular}} and {rho}{sub {parallel}}, electron-phonon coupling constants are extracted. The resulting values of {lambda}{sub tr} compare reasonably well with {lambda} from {ital T}{sub {ital c}} for the ten superconducting elements and provide new information on electron-phonon coupling for the four that are not. In particular, {lambda}{sub tr} for Mg is sufficiently low as to discourage a further search for superconductivity, whereas {lambda}{sub tr} for Sc and Y is sufficiently high (0.5--0.6) to require spin-fluctuation suppression of {ital T}{sub {ital c}} and motivate a low-{ital T} search for exotic superconductivity. Co is found to have very weak electron-phonon coupling in the majority-spin band and much stronger specific-heat enhancement in the minority-spin band. The anisotropy {rho}{sub {ital zz}}/{rho}{sub xx}={rho}{sub {parallel}}/{rho}{sub {perpendicular}} is moderately well accounted for by the anisotropy of the Drude plasma frequency ({Omega}{sub {ital p}}{sup 2}){sub xx}/({Omega}{sub p}{sup 2}){sub zz} ={l angle}{ital v}{sub {ital x}}{sup 2}{r angle}/{l angle}v{sub z}{sup 2}{r angle}, except for the {ital sp} elements, which have significant scattering anisotropy ({lambda}{sub {ital zz}}/{lambda}{sub xx}{ne}1). A systematic onset of resistivity saturation'' (signifying a breakdown of Boltzmann theory) is found when the mean free path {ital l}{le}10 A. The onset occurs at a variable value 40{lt}{rho}{lt}160 {mu}{Omega} cm.
- OSTI ID:
- 5651383
- Journal Information:
- Physical Review (Section) B: Condensed Matter; (USA), Journal Name: Physical Review (Section) B: Condensed Matter; (USA) Vol. 39:9; ISSN PRBMD; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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