Anomalous thermoelectric effect derived from strongly correlated electrons

2016 Fiscal Year Final Research Report

• Project/Area Number: 25420723
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Inorganic materials/Physical properties
• Research Institution: National Institute for Materials Science
• Principal Investigator: Isobe Masaaki 国立研究開発法人物質・材料研究機構, 機能性材料研究拠点・強相関物質グループ, グループリーダー (10354309)
• Project Period (FY): 2013-04-01 – 2017-03-31
• Keywords: 熱電材料 / 遷移金属酸化物 / 強相関電子系 / 磁性 / 計算物理

Outline of Final Research Achievements

We have studied thermoelectric properties and electronic structure of the novel cobalt oxide Ca1-xNaxCo2O4 (0<= x <= 0.6). The Na-substituted phases with x = 0.5 ~ 0.6 exhibit metallic behavior of transport properties with large thermoelectric power comparable to those in layered cobalt oxides. We found that the Ca1-xNaxCo2O4 metallic phases have 1-dimensional-like large Fermi surfaces on the Gamma-Y direction in the momentum space. Wilson ratio is estimated to be 2 ~ 3, which is moderately strong electronic correlation. Origin of the large thermoelectric power is discussed from the viewpoint of the band structure and the electronic correlation in the 3d electron system.

Free Research Field

強相関物質