论文标题
Hall效应的证据证明了电子相关性与Na级诱导电子带拓扑之间的相互作用Naxcoo2
Hall effect evidence for an interplay between electronic correlations and Na order induced electronic bands topology in NaxCoO2
论文作者
论文摘要
拓扑结构对分层化合物的物理特性的发生率已在半法中进行了广泛的研究。到目前为止，在存在电子相关性的情况下如何进化的人如何进化。在此处考虑的naxcoo2钠钴钠中，大约15年前已经披露了与CO位点相关性相关的意外磁性。这些钴物质的稳定阶段的独特NA顺序已显示出与COO2平面中的大尺寸单位细胞的特定CO电荷不成比例，与各种磁性行为有关。这为这些分层材料的拓扑与相关性之间的相互作用研究提供了原始的操场。我们在这里介绍了一系列单晶的传输测量结果，并证明我们确实将具有相当可重现的传输特性的纯相合成。我们表明，无论na内容如何，这些房间都表现出类似的行为。相反，我们提供了霍尔效应的巨大多样性的证据低温依赖，这强调了NA顺序引起的费米表面重建的特异性。我们详细研究了两个金属相之间的差异，一个（x = 0.77）抗磁磁性低于tn = 22 K，第二个（x = 2/3）的顺磁性向下t = 0。两者都显示出霍尔效应的符号变化，并减少了T。我们证明这可以归因于完全不同的物理效应。对于X = 0.77相，负霍尔效应在与各种磁性金属中发现的异常霍尔效应相似的条件下发生。在X = 2/3中，必须分配给其费米表面的特异性。在这两种情况下，在大厅效应中检测到的异常肯定与其CO电子频带的拓扑相关。
The incidence of topology on the band structure and physical properties of layered compounds has been extensively studied in semimetals. How those evolve in presence of electronic correlations has been less investigated so far. In the sodium cobaltates NaxCoO2 considered here, unexpected magnetic properties associated with correlations on the Co sites have been disclosed about 15 years ago. The distinct Na orders of the stable phases of these cobaltates have been shown to induce specific Co charge disproportionation with large size unit cells in the CoO2 planes, linked with the diverse magnetic behaviors. This provides an original playground in the studies of interplays between topology and correlations in these layered materials. We present here transport measurements on a series of single crystals and demonstrate that we do synthetize pure phases with quite reproducible transport properties. We show that above room T those display a similar behavior whatever the Na content. On the contrary we provide evidence for a great diversity in Hall effect low temperature dependences which underlines the specificities of the Fermi Surface reconstructions induced by the Na order. We study in some detail the difference between two metallic phases, one (x = 0.77) antiferromagnetic below TN = 22 K and the second (x = 2/3) paramagnetic down to T = 0. Both show a sign change in the Hall effect with decreasing T. We demonstrate that this can be attributed to quite distinct physical effects. For the x = 0.77 phase the negative Hall effect occurs in similar conditions to the anomalous Hall effect found in various magnetic metals. In the x = 2/3 phase have to be assigned to specificities of its Fermi surface. In both cases the anomalies detected in the Hall effect are certainly associated with the topology of their Co electronic bands.
