From LaH10 to room–temperature superconductors

Abstract

Abstract Thermodynamic parameters of the LaH 10 superconductor were an object of our interest. LaH 10 is characterised by the highest experimentally observed value of the critical temperature: $${{\boldsymbol{T}}}_{{\boldsymbol{C}}}^{{\boldsymbol{a}}}={\bf{215}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>C</mml:mi></mml:mrow><mml:mrow><mml:mi>a</mml:mi></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mn>215</mml:mn></mml:math> K ( p a = 150 GPa) and $${{\boldsymbol{T}}}_{{\boldsymbol{C}}}^{b}={\bf{260}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>C</mml:mi></mml:mrow><mml:mrow><mml:mi>b</mml:mi></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mn>260</mml:mn></mml:math> K ( p b = 190 GPa). It belongs to the group of superconductors with a strong electron-phonon coupling ( λ a ~ 2.2 and λ b ~ 2.8). We calculated the thermodynamic parameters of this superconductor and found that the values of the order parameter, the thermodynamic critical field, and the specific heat differ significantly from the values predicted by the conventional BCS theory. Due to the specific structure of the Eliashberg function for the hydrogenated compounds, the qualitative analysis suggests that the superconductors of the La δ X 1− δ H 10 -type (LaXH-type) structure, where X ∈ {Sc, Y}, would exhibit significantly higher critical temperature than T C obtained for LaH 10 . In the case of LaScH we came to the following assessments: $${{\boldsymbol{T}}}_{{\boldsymbol{C}}}^{{\boldsymbol{a}}}\in \left\langle {\bf{220}},{\bf{267}}\right\rangle $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>C</mml:mi></mml:mrow><mml:mrow><mml:mi>a</mml:mi></mml:mrow></mml:msubsup><mml:mo>∈</mml:mo><mml:mfenced><mml:mrow><mml:mn>220</mml:mn><mml:mo>,</mml:mo><mml:mn>267</mml:mn></mml:mrow></mml:mfenced></mml:math> K and $${{\boldsymbol{T}}}_{{\boldsymbol{C}}}^{{\boldsymbol{b}}}\in \left\langle {\bf{263}},{\bf{294}}\right\rangle $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>C</mml:mi></mml:mrow><mml:mrow><mml:mi>b</mml:mi></mml:mrow></mml:msubsup><mml:mo>∈</mml:mo><mml:mfenced><mml:mrow><mml:mn>263</mml:mn><mml:mo>,</mml:mo><mml:mn>294</mml:mn></mml:mrow></mml:mfenced></mml:math> K, while the results for LaYH were: $${{\boldsymbol{T}}}_{{\boldsymbol{C}}}^{{\boldsymbol{a}}}\in \left\langle {\bf{218}},{\bf{247}}\right\rangle $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>C</mml:mi></mml:mrow><mml:mrow><mml:mi>a</mml:mi></mml:mrow></mml:msubsup><mml:mo>∈</mml:mo><mml:mfenced><mml:mrow><mml:mn>218</mml:mn><mml:mo>,</mml:mo><mml:mn>247</mml:mn></mml:mrow></mml:mfenced></mml:math> K and $${{\boldsymbol{T}}}_{{\boldsymbol{C}}}^{{\boldsymbol{b}}}\in \left\langle {\bf{261}},{\bf{274}}\right\rangle $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>C</mml:mi></mml:mrow><mml:mrow><mml:mi>b</mml:mi></mml:mrow></mml:msubsup><mml:mo>∈</mml:mo><mml:mfenced><mml:mrow><mml:mn>261</mml:mn><mml:mo>,</mml:mo><mml:mn>274</mml:mn></mml:mrow></mml:mfenced></mml:math> K.

Topics & Concepts