Origin of Weak Pseudogap Behaviors in Na0.35CoO2: Absence of Small Hole Pockets
Origin of Weak Pseudogap Behaviors in Na0.35CoO2: Absence of Small Hole Pockets
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DOI：
10.1143/jpsj.74.2161
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发表时间：
2005-05
影响因子：
1.7
通讯作者：
K. Yada;H. Kontani
中科院分区：
文献类型：
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作者：
K. Yada;H. Kontani
采用具有完全d轨道自由度的有效d - p模型，在涨落交换近似下，对Na0.35CoO2的正常电子态进行了理论分析.电子态敏感地依赖于费米面的拓扑结构，费米面的拓扑结构随着三角形变引起的晶体电分裂（CES）而变化。我们成功地再现了弱赝能隙行为的态密度（DOS）和均匀磁化率低于300 K，假设LDA带计算预测的六个小孔口袋缺席。相反，如果这些口袋存在，“反伪差距行为”应该不可避免地出现。因此，本研究强烈支持的情况下，在钠0.35 CoO 2的小孔口袋，最近的ARPES测量报告。一个大的费米面周围的Γ-点可以解释超导电性的水插层样品。
We analyze the normal electronic states of Na 0.35 CoO 2 based on the effective d – p model with a full d -orbital freedom using the fluctuation-exchange (FLEX) approximation. The electronic states sensitively depend on the topology of Fermi surfaces, which changes with the crystalline electric splitting (CES) due to the trigonal deformation. We succeed in reproducing the weak pseudogap behaviors in the density of states (DOS) and in the uniform magnetic susceptibility below 300 K, assuming that six small hole pockets predicted by LDA band calculations are absent . If these pockets exist, on the contrary, “anti-pseudogap behaviors” should inevitably appear. Thus, the present study strongly supports the absence of the small hole pockets in Na 0.35 CoO 2 , as reported by recent ARPES measurements. A large Fermi surface around the Γ-point would account for the superconductivity in water-intercalated samples.