Critical fields and specific heat of LuNi 2 B 2 C
Critical fields and specific heat of LuNi 2 B 2 C
复制标题
LuNi 2 B 2 C的临界场和比热
DOI：
10.1103/physrevb.63.134519
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发表时间：
2001
影响因子：
3.7
通讯作者：
J. Smith
中科院分区：
文献类型：
--
作者：
G. M. Schmiedeshoff;J. Detwiler;W. Beyermann;A. Lacerda;P. Canfield;J. Smith
We have measured the upper critical magnetic field, lower critical magnetic field, and low-temperature specific heat of ${\mathrm{LuNi}}_{2}{\mathrm{B}}_{2}\mathrm{C}.$ Our upper critical-field measurements above $\ensuremath{\sim}2\mathrm{K}$ are consistent with earlier measurements by other groups. The upper critical field exhibits a finite slope as $\stackrel{\ensuremath{\rightarrow}}{T}0,$ and we discuss possible origins of this very unusual behavior. We observe a linear temperature dependence for the lower critical field of our single-crystal sample, a temperature dependence that disagrees with earlier measurements on polycrystals and suggests that the lower critical field may be anisotropic. The Sommerfeld coefficient increases with magnetic field as ${H}^{\ensuremath{\epsilon}}$ with $\ensuremath{\epsilon}=0.63\ifmmode\pm\else\textpm\fi{}0.12$ in qualitative agreement with earlier work. The temperature dependence of the zero-field electronic specific heat is exponential well below ${T}_{c}.$ We discuss our results in light of recent proposals of both anisotropic s-wave and d-wave superconductivity for ${\mathrm{LuNi}}_{2}{\mathrm{B}}_{2}\mathrm{C}.$ Our data seem most consistent with strong-coupling superconductivity and a weakly anisotropic s-wave energy gap.
We have measured the upper critical magnetic field, lower critical magnetic field, and low-temperature specific heat of ${\mathrm{LuNi}}_{2}{\mathrm{B}}_{2}\mathrm{C}.$ Our upper critical-field measurements above $\ensuremath{\sim}2\mathrm{K}$ are consistent with earlier measurements by other groups. The upper critical field exhibits a finite slope as $\stackrel{\ensuremath{\rightarrow}}{T}0,$ and we discuss possible origins of this very unusual behavior. We observe a linear temperature dependence for the lower critical field of our single-crystal sample, a temperature dependence that disagrees with earlier measurements on polycrystals and suggests that the lower critical field may be anisotropic. The Sommerfeld coefficient increases with magnetic field as ${H}^{\ensuremath{\epsilon}}$ with $\ensuremath{\epsilon}=0.63\ifmmode\pm\else\textpm\fi{}0.12$ in qualitative agreement with earlier work. The temperature dependence of the zero-field electronic specific heat is exponential well below ${T}_{c}.$ We discuss our results in light of recent proposals of both anisotropic s-wave and d-wave superconductivity for ${\mathrm{LuNi}}_{2}{\mathrm{B}}_{2}\mathrm{C}.$ Our data seem most consistent with strong-coupling superconductivity and a weakly anisotropic s-wave energy gap.