{"id":8095,"date":"2023-05-26T07:42:37","date_gmt":"2023-05-26T14:42:37","guid":{"rendered":"http:\/\/physikon.net\/?p=8095"},"modified":"2025-01-24T09:22:29","modified_gmt":"2025-01-24T17:22:29","slug":"i34the","status":"publish","type":"post","link":"http:\/\/physikon.net\/?p=8095","title":{"rendered":"Superconducting I<\/em>4<\/span>3m<\/em> CSH7<\/sub> Model Applied to Resistive Transition Temperature Data for Compressed C-S-H at High Pressure"},"content":{"rendered":"

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Superconducting I<\/em>4<\/span>3m<\/em> CSH7<\/sub> Model Applied to Resistive Transition Temperature Data for Compressed C-S-H at High Pressure<\/strong>, Dale R. Harshman and Anthony T. Fiory [arXiv_3<\/a>]\n

This article updates version 1 by restricting consideration to only the resistive data and excluding the questioned 287.7-K datum reported for carbonaceous sulfur hydride in Snider et al., Nature 585<\/b>, 373 (2020). The superconducting transitions are considered in terms of the theoretically-discovered compressed I<\/em>4<\/span>3m<\/em> CSH7<\/sub> structure of Sun et al., Phys. Rev. B 101<\/b>, 174102 (2020), which comprises a sublattice similar to Im<\/em>3<\/span>m<\/em> H3<\/sub>S with CH4<\/sub> intercalates. Positing an electronic genesis of the superconductivity, a model is presented in analogy with earlier work on superconductivity in Im<\/em>3<\/span>m<\/em> H3<\/sub>S, in which pairing is induced via purely electronic Coulomb interactions across the mean distance \u03b6 between the S and H4<\/sub> tetrahedra enclosing C. Theoretical superconducting transition temperatures for I<\/em>4<\/span>3m<\/em> CSH7<\/sub> are derived as T<\/em>C0<\/sub> = (2\/3)1\/2<\/sup>\u03c31\/2<\/sup>\u03b2\/a<\/em>\u03b6, where \u03b2 = 1247.4 \u00c52<\/sup>K is a universal constant, \u03c3 is the participating charge fraction, and a<\/em> is the lattice parameter. Analysis suggests persistent bulk superconductivity with a pressure-dependent \u03c3, increasing from \u03c3 = 3.5, determined previously for Im<\/em>3<\/span>m<\/em> H3<\/sub>S, to \u03c3 = 7.5 at high pressure owing to additionally participating C-H bond electrons. With an and \u03b6 determined by theoretical structure, calculations of T<\/em>C0<\/sub> at the highest pressures, 258 and 271 GPa, are in agreement with resistive transitions to within an overall uncertainty of \u00b1 3.5 K.<\/p>\n\n

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FIG. 1.<\/b> Schematic structure of I<\/em>4<\/span>3m<\/em> CSH7<\/sub>, indicating the four distances \u03b61<\/sub>, \u03b62<\/sub>, \u03b63<\/sub>, and \u03b64<\/sub> for calculating the average \u03b6, the H4<\/sub>-tetrahedron, and coordinates of S ions located at cube corners.<\/figcaption><\/figure>\n<\/div>\n\n
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FIG. 2.<\/b> The extracted \u03c3(X)<\/sup> from resistance data (open circles) as defined in Eq. (3), plotted as a function of pressure P<\/em>. The solid blue curve is a fit of the function \u03c3(em>P) from Eq. (5) to the data. The dotted curves represent the calculated uncertainty. The dashed horizontal lines at 3.5, 5.5, and 7.5 correspond to charge fractions for H3<\/sub>S (7\/2), H3<\/sub>S + H4<\/sub> (11\/2), and H3<\/sub>S + CH4<\/sub> (15\/2), respectively. Questioned resistive datum: pink color.<\/figcaption><\/figure>\n<\/div>\n\n
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FIG. 3.<\/b> Measured resistance transition temperature T<\/em>C<\/sub> vs. pressure P<\/em> after Ref. 1 (open circles). The solid blue curve is T<\/em>C0<\/sub>(P<\/em>) from Eq. (6) to the data. The dotted blue curves represent the calculated uncertainty. Questioned resistive datum: pink color.<\/figcaption><\/figure>\n<\/div>\n\n
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FIG. 4.<\/b> Measured T<\/em>C<\/sub> vs. calculated T<\/em>C0<\/sub> for compressed high-T<\/em>C<\/sub> superconductors; I<\/em>4<\/span>3m<\/em> CSH7<\/sub> (258-271 GPa), Fm<\/em>3<\/span>m<\/em> LaH10<\/sub> (169 and 192 GPa) [29], Im<\/em>3<\/span>m<\/em> H3<\/sub>S (155 GPa) [27], HgBa2<\/sub>Ca2<\/sub>Cu3<\/sub>O8+\u03b4<\/sub> (25 GPa) [28], YBa2<\/sub>Cu3<\/sub>O8<\/sub> (12 GPa) [29], A15 Cs3<\/sub>C60<\/sub> (0.93 GPa) [30], FeSe0.977<\/sub> (7.5 GPa) [43], Fe1.03<\/sub>Se0.57<\/sub>Te0.43<\/sub> (2.3 GPa) [43], and C\/C (twisted bilayer graphene device D2, 1.33 GPa) [44]. The solid line represents Eq. (1), highlighting the equality between TC<\/sub> and T<\/em>C0<\/sub>.<\/em><\/em><\/figcaption><\/figure>\n<\/div>\n\n\n

Dale R. Harshman and Anthony T. Fiory, arXiv:2201.01860v3 [cond-mat.supr-con] (2023)<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,8,28],"tags":[],"class_list":["post-8095","post","type-post","status-publish","format-standard","hentry","category-high-tc-superconductivity","category-high-tc-theory","category-transition-temperature"],"_links":{"self":[{"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts\/8095","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=8095"}],"version-history":[{"count":28,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts\/8095\/revisions"}],"predecessor-version":[{"id":8367,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts\/8095\/revisions\/8367"}],"wp:attachment":[{"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=8095"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=8095"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=8095"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}