Charge density waves in Lanthanoid low-dimensional materials sensitive to external field observed by x-ray camera under Magnetic field.

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K05404
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: Okayama University
• Principal Investigator: Nogami Yoshio 岡山大学, 自然科学研究科, 教授 (10202251)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 電荷密度波 / 低次元物質 / 放射光 / 強磁場 / 構造物性 / 磁気抵抗

Outline of Final Research Achievements

Charge density wave 1(CDW1) (1/2 0.5+δ 0）was observed for rare-earth low-dimensional materials RNIC2. The CDW1 was very sensitive to the external field such as magnetic field and physical pressure. In the present study, we developed single crystals for heavy rare-earth RNIC2 and observed another modulated structure at the reduced wave vector of (1/2 1/2 1/2) at higher transition temperature than that of CDW1. Using atomic coordinates observed Synchrotron radiation diffraction of CDW2 superstructure, we calculated the electronic structure and found the wave vector (1/2 1/2 1/2) of CDW2 was equal to the nesting vector of the Fermi surface. We proposed the structural phase diagram for RNIC2 including CDW1 and CDW2.

Free Research Field

固体物理

Academic Significance and Societal Importance of the Research Achievements

磁場に反応して磁気抵抗が大きく変化する物質はGMRやCMRと呼ばれ、ノーベル物理学賞の受賞理由にもなり、磁気記憶媒体の分野で産業的にも貢献してきた。このような重要性にも関わらず、クロム鉄積層薄膜やマンガン酸化物など、物質系が限定されてきたため最近の研究の展開はあまり進んでいない。本物質は低温でCDW1の消失に伴い約10倍の巨大磁気抵抗を示し、新たな巨大磁気抵抗物質となり得る。我々はこの物質にこれまで知られているCDW1の他にCDW2という新たな抵抗増加要因を見出し、その発生原因について明らかにした。