Ultra high pressure synthesis of novel rare-earth borides with cage structure and their physical properties under extremal conditions

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K05431
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Ibaraki University
• Principal Investigator: Iga Fumitoshi 茨城大学, 理工学研究科(理学野), 教授 (60192473)
• Research Collaborator: SHIMIZU katsuya ; KAGAYAMA tomoko ; SATO hitoshi ; SATO keisuke
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 高圧力 / 希土類ホウ化物 / 新機能性物質開発 / 強相関電子系 / 磁性 / X線構造解析

Outline of Final Research Achievements

This research purpose is to produce the novel functional rare-earth hexaborides RB6 and dodecaborides RB12, which have been studied as the various strongly correlated electron systems, by using high pressure synthesis method and to investigate their exotic physical properties. Especially our target materials were CeB12, PrB12 and TmB6. They are expected to exhibit heavy fermion feature, valence fluctuation, multipole ordering, Kondo insulating and topological properties. These compounds have been studied by non-magnetic ion substitution for such target materials. Furthermore, Ca-substituted alloying for Kondo insulator YbB12 was for the first time succeeded by high-pressure synthesis. In this alloy, the magnitude of the Kondo insulator's energy gap was found invariant for Ca-doping.

Free Research Field

磁性、強相関物性、物質開発

Academic Significance and Societal Importance of the Research Achievements

これまで作ることが難しいと考えられていた希土類ホウ化物の空白領域作製に,高圧合成手法を用いて挑戦し,SmB12,GdB12合成成功など,一定の成果を上げることができた。YB12を母合金としてCe,Pr置換も２０％近くまで,２３万気圧という超高圧を使用して実現させた。また高圧力を使えば,表面が金属で中は絶縁体というトポロジカル近藤絶縁体のような興味深い機能性物質の開発を推進できることが示せた。