Strong charge fluctuations manifested in the high-temperature Hall coefficient of high-Tc cuprates
Strong charge fluctuations manifested in the high-temperature Hall coefficient of high-Tc cuprates
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DOI：
10.1103/physrevb.75.024515
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发表时间：
2007-01-01
影响因子：
3.7
通讯作者：
Ando, Yoichi
中科院分区：
文献类型：
--
作者：
Ono, S.;Komiya, Seiki;Ando, Yoichi
通过测量La_2CuO_4、Pr_（1.3）La_（0.7）CuO_4和La_（2-x）Sr_xCuO_4（LSCO）在1000 K范围内的霍尔系数R-H，我们发现在高温下x=0-0.05时，LSCO中R-H的温度（T）依赖性无疑意味着载流子被热激活的间隙，这又表明在轻掺杂的铜氧化物中，在高温下存在强的电荷波动，并且载流子数不是常数。在较高的掺杂（x=0.08-0.21），高温R-H（T）的行为被发现是定性相同的，虽然有一个减弱的温度依赖性，我们试图理解其行为的现象学双载流子模型，其中热激活被认为是两个物种之一。尽管该模型的原油性质，我们的分析给出了一个合理的帐户R-H在高温和0 K的范围广泛的掺杂，这表明在一个间隙的电荷波动仍然很重要，在高温LSCO深入到超导掺杂制度。此外，我们的模型提供了一个角度来理解看似矛盾的高温行为的R-H和面内电阻率接近最佳掺杂的一致的方式。最后，我们讨论了可能的影响，我们的结果等问题的散射时间分离和大的赝隙。
By measuring the Hall coefficient R-H up to 1000 K in La2CuO4, Pr1.3La0.7CuO4, and La2-xSrxCuO4 (LSCO), we found that the temperature (T) dependence of R-H in LSCO for x=0-0.05 at high temperature undoubtedly signifies a gap over which the charge carriers are thermally activated, which in turn indicates that in lightly doped cuprates strong charge fluctuations are present at high temperature and the carrier number is not a constant. At higher doping (x=0.08-0.21), the high-temperature R-H(T) behavior is found to be qualitatively the same, albeit with a weakened temperature dependence, and we attempt to understand its behavior in terms of a phenomenological two-carrier model where the thermal activation is considered for one of the two species. Despite the crude nature of the model, our analysis gives a reasonable account of R-H both at high temperature and at 0 K for a wide range of doping, suggesting that charge fluctuations over a gap remain important at high temperature in LSCO deep into the superconducting doping regime. Moreover, our model gives a perspective to understand the seemingly contradicting high-temperature behavior of R-H and the in-plane resistivity near optimum doping in a consistent manner. Finally, we discuss possible implications of our results for such issues as the scattering-time separation and the large pseudogap.