Correlation between crystal structures of CaAlSi with and without superlattice and superconducting properties
Correlation between crystal structures of CaAlSi with and without superlattice and superconducting properties
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DOI：
10.1103/physrevb.74.014517
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发表时间：
2006-07
影响因子：
3.7
通讯作者：
S. Kuroiwa;H. Sagayama;T. Kakiuchi;H. Sawa;Y. Noda;J. Akimitsu
中科院分区：
文献类型：
--
作者：
S. Kuroiwa;H. Sagayama;T. Kakiuchi;H. Sawa;Y. Noda;J. Akimitsu
We have succeeded in growing a phase in $\mathrm{CaAlSi}$ with Al and Si atoms being distributed regularly in the $\mathrm{AlSi}$ layer corresponding to the ${\mathrm{B}}_{2}$ plane in the ${\mathrm{AlB}}_{2}$-type structure without a superlattice along the $c$ axis. The field-induced magnetic response in a phase exhibits an almost isotropic characteristic for the respective crystal axis. Moreover, the $2\mathrm{\ensuremath{\Delta}}(0)∕{k}_{\mathrm{B}}{T}_{\mathrm{c}}$ and $\mathrm{\ensuremath{\Delta}}{C}_{\mathrm{el}}∕{\ensuremath{\gamma}}_{\mathrm{N}}{T}_{\mathrm{c}}$ estimated by heat capacity measurements are $\ensuremath{\sim}3.5$ and $\ensuremath{\sim}1.4$, respectively, indicating a BCS superconductor with a weak coupling. Although $\mathrm{CaAlSi}$ has a two-dimensional layered structure, these results strongly suggest that the superconductivity of the phase in $\mathrm{CaAlSi}$ is derived from a three-dimensional electronic ground state such as a conventional $s$-wave superconductor, which is markedly different from those of superstructured $\mathrm{CaAlSi}$.
We have succeeded in growing a phase in $\mathrm{CaAlSi}$ with Al and Si atoms being distributed regularly in the $\mathrm{AlSi}$ layer corresponding to the ${\mathrm{B}}_{2}$ plane in the ${\mathrm{AlB}}_{2}$-type structure without a superlattice along the $c$ axis. The field-induced magnetic response in a phase exhibits an almost isotropic characteristic for the respective crystal axis. Moreover, the $2\mathrm{\ensuremath{\Delta}}(0)∕{k}_{\mathrm{B}}{T}_{\mathrm{c}}$ and $\mathrm{\ensuremath{\Delta}}{C}_{\mathrm{el}}∕{\ensuremath{\gamma}}_{\mathrm{N}}{T}_{\mathrm{c}}$ estimated by heat capacity measurements are $\ensuremath{\sim}3.5$ and $\ensuremath{\sim}1.4$, respectively, indicating a BCS superconductor with a weak coupling. Although $\mathrm{CaAlSi}$ has a two-dimensional layered structure, these results strongly suggest that the superconductivity of the phase in $\mathrm{CaAlSi}$ is derived from a three-dimensional electronic ground state such as a conventional $s$-wave superconductor, which is markedly different from those of superstructured $\mathrm{CaAlSi}$.