Doping dependence of the spatially modulated dynamical spin correlations and the superconducting-transition temperature in La 2-x Sr x CuO 4
Doping dependence of the spatially modulated dynamical spin correlations and the superconducting-transition temperature in La 2-x Sr x CuO 4
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DOI：
10.1103/physrevb.57.6165
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发表时间：
1998-03
影响因子：
3.7
通讯作者：
Kohta Yamada;C. H. Lee;K. Kurahashi;J. Wada;S. Wakimoto;S. Ueki;H. Kimura;Y. Endoh;S. Hosoya-S.-Ho
中科院分区：
文献类型：
--
作者：
Kohta Yamada;C. H. Lee;K. Kurahashi;J. Wada;S. Wakimoto;S. Ueki;H. Kimura;Y. Endoh;S. Hosoya-S.-Ho
对浮区生长的${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$单晶进行了系统的低能中子散射研究，从零掺杂($x=0$)扩展到过掺杂的弱超导区域，$x=0.25$。对于超过临界掺杂值${x}_{c}的$x$，低能自旋涨落峰位置从($\FRAC{1}{2}$，$\FRAC{1}{2}$)移动到($\frac{1}{2}$\ifmmode\pm\else\textpm\fi{}\ensuremath{\delta}，$\FRAC{1}{2}$)，以及($\FRAC{1}{2}$，$\frac{1}{2}$\ifmmode\pm\else\textpm\fi{}\ensuremath{\delta})；${x}_{c}也代表超导的起始浓度。对于$0.06l~xl~0.12$，不可公度性$\EnsureMath{\Delta}$近似遵循定量关系$\Ensureath{\Delta}=x$。然而，超出$x0.12$之后，不可通约性往往会在$\EnsureMath{\Delta}\EnsureMath1/8$附近饱和。在一定掺杂量下，样品的超导转变温度为{T}_{c}(X)$，并与最佳掺杂量呈线性关系，直至最佳掺杂量。低能自旋涨落的峰值动量宽度在整个超导浓度区都很小，但在强过掺杂区除外。观察到$x=\FRAC{1}{8}$的宽度异常小。研究发现，无公度的空间调制对于降低${T}_{c}的配对断裂效应是稳健的，例如样品的脱氧或用锌取代铜。
Systematic low-energy neutron-scattering studies have been performed on float-zone-grown single crystals of ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ with $x$ extending from zero doping, $x=0$, to the overdoped, weakly superconducting regime, $x=0.25$. For $x$ beyond a critical doping value of ${x}_{c}\ensuremath{\approx}0.05$ the low-energy spin-fluctuation peak position shifts from ($\frac{1}{2}$, $\frac{1}{2}$) to ($\frac{1}{2}$\ifmmode\pm\else\textpm\fi{}\ensuremath{\delta}, $\frac{1}{2}$), and ($\frac{1}{2}$, $\frac{1}{2}$\ifmmode\pm\else\textpm\fi{}\ensuremath{\delta}); ${x}_{c}$ also represents the onset concentration for superconductivity. For $0.06l~xl~0.12$ the incommensurability $\ensuremath{\delta}$ follows approximately the quantitative relation $\ensuremath{\delta}=x$. However, beyond $x\ensuremath{\approx}0.12$ the incommensurability tends to saturate around $\ensuremath{\delta}\ensuremath{\approx}1/8$. The superconducting-transition temperature ${T}_{c}(x)$ for stoichiometric samples at a given doping scales linearly with $\ensuremath{\delta}$ up to the optimal doping value of $x$. The peak momentum width of the spin fluctuations at low energies is small throughout the superconducting concentration region except in the strongly overdoped region. An anomalously small width is observed for $x=\frac{1}{8}$. The incommensurate spatial modulation is found to be robust with respect to pair-breaking effects that lower ${T}_{c},$ such as deoxygenation of the sample or replacement of Cu by Zn.