Control of spin/orbital degrees of freedom and study of critical behavior in 1-dimensional triangle lattice system

2014 Fiscal Year Final Research Report

• Project/Area Number: 24540373
• 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: Osaka University
• Principal Investigator: MIYASAKA Shigeki 大阪大学, 理学(系)研究科(研究院), 准教授 (70345106)
• Co-Investigator(Renkei-kenkyūsha): TAJIMA Setsuko 大阪大学, 大学院理学研究科, 教授 (70188241) ; MURAKAMI Youichi 大学共同利用機関法人高エネルギー加速器研究機構, 物質構造科学研究所, 教授 (60190899) ; KUMAI Reiji 大学共同利用機関法人高エネルギー加速器研究機構, 物質構造科学研究所, 教授 (00356924) ; NAKAO Hironori 大学共同利用機関法人高エネルギー加速器研究機構, 物質構造科学研究所, 准教授 (70321536)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 軌道秩序 / スピンフラストレーション / 金属-絶縁体転移 / 量子臨界点

Outline of Final Research Achievements

Critical behaviors of spin/orbital order have been investigated in geometrically frustrated system CaV2O4. CaV2O4 is a Mott insulator, and undergoes orbital order transition around 110 K with decreasing temperature. As a result, spin frustration is suppressed, and CaV2O4 shows antiferromagnetic long-range order below 50 K. The substitution of Cr with 3d3 electronic configuration for V with 3d2 causes the electron doping in this system. The Cr doping induces the disappearance of orbital order, resultantly recovers the spin frustration, and suppresses the long-range magnetic order. In the Cr-doped CaV2O4, we have succeeded in the control of orbital order and spin frustration, which are competing. In addition, the Cr doping induces the metal-insulator transition (Mott transition) as well as spin/orbital order-disorder. At the critical point of spin/orbital order near Mott transition, the non-Fermi liquid behavior by strong spin/orbital fluctuation has been observed.

Free Research Field

物性物理