Enhanced Seebeck coefficient by a filling-induced Lifshitz transition in KxRhO2
Enhanced Seebeck coefficient by a filling-induced Lifshitz transition in KxRhO2
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DOI：
10.1103/physrevb.99.041112
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发表时间：
2019-01
影响因子：
3.7
通讯作者：
N. Ito;Mayumi Ishii;R. Okazaki
中科院分区：
文献类型：
--
作者：
N. Ito;Mayumi Ishii;R. Okazaki
本文系统地测量了与热电氧化物Na$x}$CoO $_{2}$同构的层状氧化铑K$_{x}$RhO $_{2}$单晶（$0.5\lesssim x \lesssim 0.67$）的输运性质。我们发现，在$x = 0.64$以下，塞贝克系数在低温下随着$x$的增加而异常增强，而在$x=0.65$以上，它与温度成正比，就像传统金属一样，这表明存在临界含量$x^{*} \simeq 0.65$。对于这种反常行为的起源，我们讨论了填充诱导的Lifshitz转变，其特征在于在临界含量$x^*$的圆柱孔费米表面的突然拓扑变化。
We have systematically measured the transport properties in the layered rhodium oxide K$_{x}$RhO$_{2}$ single crystals ($0.5\lesssim x \lesssim 0.67$), which is isostructural to the thermoelectric oxide Na$_{x}$CoO$_{2}$. We find that below $x = 0.64$ the Seebeck coefficient is anomalously enhanced at low temperatures with increasing $x$, while it is proportional to the temperature like a conventional metal above $x=0.65$, suggesting an existence of a critical content $x^{*} \simeq 0.65$. For the origin of this anomalous behavior, we discuss a filling-induced Lifshitz transition, which is characterized by a sudden topological change in the cylindrical hole Fermi surfaces at the critical content $x^*$.