{"id":3619,"date":"2017-02-03T18:57:43","date_gmt":"2017-02-04T02:57:43","guid":{"rendered":"http:\/\/physikon.net\/?p=3619"},"modified":"2022-06-22T09:37:54","modified_gmt":"2022-06-22T16:37:54","slug":"high-tc-superconductivity-in-cs3c60-compounds-governed-by-local-cs-c60-coulomb-interactions","status":"publish","type":"post","link":"http:\/\/physikon.net\/?p=3619","title":{"rendered":"High-Tc<\/sub> Superconductivity in Cs3<\/sub>C60<\/sub> Compounds Governed by Local Cs-C60<\/sub> Coulomb Interactions"},"content":{"rendered":"

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High-T<\/em>C<\/sub>\u00a0Superconductivity in Cs3<\/sub>C60<\/sub>\u00a0Compounds Governed by Local Cs-C60<\/sub> Coulomb Interactions<\/strong>, D. R. Harshman and A. T. Fiory [arXiv<\/a>]\n

Unique among alkali-doped A<\/em>3<\/sub>C60<\/sub> fullerene compounds, the A15 and fcc forms of Cs3<\/sub>C60<\/sub> exhibit superconducting states varying under hydrostatic pressure with highest transition temperatures at T<\/em>C<\/sub>meas<\/sup> = 38.3 and 35.2 K, respectively. \u00a0Herein it is argued that these two compounds under pressure represent the optimal materials of the A<\/em>3<\/sub>C60<\/sub> family, and that the C60<\/sub>-associated superconductivity is mediated through Coulombic interactions with charges on the alkalis.\u00a0 A derivation of the interlayer Coulombic pairing model of high-T<\/em>C<\/sub> superconductivity employing non-planar geometry is introduced, generalizing the picture of two interacting layers to an interaction between charge reservoirs located on the C60<\/sub> and alkali ions.\u00a0 The optimal transition temperature follows the algebraic expression, T<\/em>C0<\/sub> = (12.474 nm2<\/sup>\u00a0K)\/\u2113\u03b6, where \u2113 relates to the mean spacing between interacting surface charges on the C60<\/sub> and \u03b6 is the average radial distance between the C60<\/sub> surface and the neighboring Cs ions.\u00a0 Values of T<\/em>C0<\/sub> for the measured cation stoichiometries of Cs3\u2013x<\/sub>C60<\/sub> with x \u00bb 0 are found to be 38.19 and 36.88 K for the A15 and fcc forms, respectively, with the dichotomy in transition temperature reflecting the larger \u03b6 and structural disorder in the fcc form.\u00a0 In the A15 form, modeled interacting charges and Coulomb potential e<\/em>2<\/sup>\/\u03b6 are shown to agree quantitatively with findings from nuclear-spin relaxation and mid-infrared optical conductivity.\u00a0 In the fcc form, suppression of T<\/em>C<\/sub>meas<\/sup> below T<\/em>C0<\/sub> is ascribed to native structural disorder.\u00a0 Phononic effects in conjunction with Coulombic pairing are discussed.<\/p>\n

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Measured optimal transition temperature T<\/em>C<\/sub>meas<\/sup> versus (\u2113\u03b6)\u20131<\/sup> for A15 Cs2.85(1)<\/sub>C60<\/sub> and fcc Cs2.901(6)<\/sub>C60<\/sub> (legend upper left), compared to other high-T<\/em>C<\/sub> superconductors: cuprates; iron pnictides and chalcogenides; intercalated group-4-metal nitride-chlorides; and RuO- and ET-based compounds (legend lower right). The line represents the theoretical T<\/em>C0<\/sub>.<\/p><\/td>\n<\/tr>\n

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Maximum measured transition temperature T<\/em>C<\/sub>max<\/sup> plotted against Rb content x in Rbx<\/sub>Cs3\u2013x<\/sub>C60<\/sub> for x = 0 and x = 0.35, 0.5, 0.75 and 1), denoted by circle symbols. Triangles denote corresponding measured Vper C60<\/sub><\/sub>. Dashed curves are guides to the eye. After Refs. [8] and [13] of paper.<\/p><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n

Dale R. Harshman and Anthony T. Fiory, J. Phys.: Condens. Matter 29<\/strong>, 145602 (2017)<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":3625,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,8,27,28],"tags":[],"class_list":["post-3619","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-high-tc-superconductivity","category-high-tc-theory","category-organic-superconductors","category-transition-temperature"],"_links":{"self":[{"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts\/3619","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3619"}],"version-history":[{"count":15,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts\/3619\/revisions"}],"predecessor-version":[{"id":7693,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts\/3619\/revisions\/7693"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/media\/3625"}],"wp:attachment":[{"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3619"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3619"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3619"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}