結構形式為Sc5Co4Si10的矽化物 Sc5M4Si10 ( M = Co、Rh、Ir) 超導溫度分別為4.9 K，8.4 K、及8.6 K。Sc5Co4Si10超導形成的原因為在費米面附近有很大的態密度，因此推測Sc5Rh4Si10 及Sc5Ir4Si10會有更大的態密度，但是Sc5Rh4Si10 及Sc5Ir4Si10藉由量測低溫比熱 (γ) 所推測出的超導溫度卻無法和實際超導溫度相近，因此這引起了我們的興趣。藉由核磁共振技術來量測這三個超導體的中央躍遷譜線和各個超導體三個不同結構位置的Sc的奈特位移和自旋晶格鬆弛時間。藉由中央躍遷譜線我們可以明確的訂出三個不相等的Sc在晶格結構中的位置。藉由奈特位移及自旋晶格鬆弛時間的量測結果，我們得知對於我們所研究材料的超導轉變溫度和費米面上的態密度無關。進一步分析發現電子-聲子耦合才是造成超導的主要原因。

The transition temperatures (Tc) of the Sc5Co4Si10-type silicide Sc5M4Si10 ( M＝Co，Rh，Ir ) are 4.9K，8.4K，8.6K，respectively. The superconductivity of Sc5Co4Si10 is attributed to the large density of state at Fermi level，especially for Sc5Rh4Si10 and Sc5Ir4Si10. The low-temperature specific heat coefficients (γ) for Sc5Rh4Si10 and Sc5Ir4Si10 could not fit the expectably transition temperature. This is what we are interested in. By NMR measurements，we got the central transition line shape of this three superconductors，and the Knight shift and spin-lattice relaxation time (T1) for each of the three crystallographic sites. From the central transition line shapes, three nonequivalent Sc sites have been identified. The results of Knight shift and spin-lattice relaxation time (T1) provide us that there are no correlation between the density of states at Fermi level and the superconductive transition temperature of the studied material. Further analyses indicate the electron-phonon coupling plays a significant role for the superconductivity of Sc5Co4Si10.

(1)H.F.Braun,K.Yvon,and R.H.Braun,Acta Crystallogr.,Sect.B:Struct. Crystallogr. Cryst. Chem. 36,2397 (1980)
(2)L.S.Hausermann-Berg and R.N.Shelton,Phys. Rev.B 33.5062 (1986)
(3)H.D.Yang,R.N.Shelton,and H.F.Braun,Phys.Rev.B 33,5062 (1986)
(4)G.C.Cater,L.H.Bennett,and D.J.Kahan, Metallic Shift In NMR (1977)
(5)Charles Kittel, Introduction to Solid State Physics,7th (1996)
(6)Po-Jen Chu,B.C.Gerstein,H.D.Yang,and R.N.Shelton,Phys. Rev.B 37,1796 (1988)
(7)G.C.Cater,L.H.Bennett,and D.J.Kahan,Metallic Shift in NMR (1977)
(8)A.Narath,Phys.Rev.162,320 (1967)
(9)J.Korringa,Physica 16,601 (1950)
(10)B.Perrin,P.Descouts,A.Dupanloup,and D.Seipler,J.Phys. F:Met.Phys. 9,673 (1979)
(11)J.W.Ross,F.Y.Fradin,L.L.Isaacs,and D.J.Lam,Physical Review 183,3 (1969)
(12)R.N.Shelton,L.S.Hausermann-Berg,P.Klavins,H.D.Yang,M.A.Anderson,and C.A.Swenson,Phys.Rev.B 34,4590 (1986)
(13)Y.K.Kuo, C.S.Lue, F.H.Hsu, H.H.Li,and H.D.Yang,Phys.Rev.B 64,125124 (2001)
(14)G.Kresse and J.Hafner,Phys. Rev.B 47,558 (1993)
(15)G.Kresse and J.Hafner,Phys. Rev.B 49,14251 (1994)
(16)G.Kresse and J.Furthmullar,Phys.Rev.B 54,11169 (1996)
(17)W.L.McMillan,Phys.Rev.167,331 (1968)
(18)P.B.Allen and R.C.Dynes,Phys.Rev.B 12,905 (1975)
(19)L.S.Hausermann-Berg,and R.N.Shelton,Phys.Rev.B 35,6659 (1987)