Structural phase transition, precursory electronic anomaly, and strong-coupling superconductivity in quasi-skutterudite (Sr1−<italic>x</italic>Ca<italic>x</italic>)3Ir4Sn13 and Ca3Rh4Sn13<xref rid="cpb_27_7_077401fn1" ref-type="fn">*</xref><fn id="cpb_27_7_077401fn1"> <label>*</label>Project supported by the National Natural Science Foundation of China (Grant Nos. 11674377 and 11634015), the National Key R&D Program of China (Grant Nos. 2017YFA0302904 and 2016YFA0300502), and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB07020200). J. Y. is supported by the Youth Innovation Promotion Association of CAS.</fn>

Structural phase transition, precursory electronic anomaly, and strong-coupling superconductivity in quasi-skutterudite (Sr_1−xCa_x)₃Ir₄Sn₁₃ and Ca₃Rh₄Sn₁₃* *

Project supported by the National Natural Science Foundation of China (Grant Nos. 11674377 and 11634015), the National Key R&D Program of China (Grant Nos. 2017YFA0302904 and 2016YFA0300502), and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB07020200). J. Y. is supported by the Youth Innovation Promotion Association of CAS.

Luo Jun^{1, 2}, Yang Jie^{1, †}, Maeda S³, Li Zheng^{1, 2}, Zheng Guo-Qing^{1, 2, 3, ‡}

(color online) The crystal structure of (Sr_1−xCa_x)₃Ir₄Sn₁₃ and Ca₃RH₄Sn₁₃ that contain two different Sn sites, and the ¹¹⁹Sn-NMR spectra for (Sr_1−xCa_x)₃Ir₄Sn₁₃ (x = 0, 0.5, 1) and Ca₃RH₄Sn₁₃ at 250 K. The horizontal coordinate represents the reduced frequency f/f₀, with f₀ = γH₀/2π. The blue and red dotted lines are Gaussian fittings to the obtained spectra with area ratio of 1 : 12. The solid lines are the sum of the two Gaussian functions.