Study of metal-insulator transition in the 5d transition metal pyrochlore oxide Cd2Os2O7

2014 Fiscal Year Final Research Report

• Project/Area Number: 24540360
• 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: Tokyo Institute of Technology
• Principal Investigator: YAMAURA Jun-ichi 東京工業大学, 元素戦略研究センター, 特任准教授 (80292762)
• Co-Investigator(Renkei-kenkyūsha): 廣井 善二 東京大学, 物性研究所, 教授 (30192719) ; 筒井 智嗣 高輝度光科学研究センター, 利用研究促進部門, 研究員 (30192719) ; 長谷川 巧 広島大学, 総合科学研究科, 助教 (20508171) ; 堀場 律子 岡山大学, 自然科学研究科, 助教 (50415098) ; 大串 研也 東北大学, 理学部, 教授 (30455331)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 金属絶縁体転移 / 反強磁性転移 / 磁気構造 / 共鳴X線散乱 / リフシッツ転移

Outline of Final Research Achievements

5d-transition metal pyrochlore oxide Cd2Os2O7 shows a metal-insulator transition at 227 K with magnetic ordering. The pyrochlore lattice is composed of the corner-shared tetrahedral Os network, in which the Os atoms have functions as the electric conduction and/or the magnetic moment. Since a geometrical frustration between localized spins prevents a long-range magnetic ordering, a peculiar magnetic structure is expected in the ordered state. We observed a commensurate magnetic peak of q = (0, 0, 0) by resonant x-ray scattering in a high-quality single crystal. We propose a noncollinear all-in/all-out spin arrangement on the pyrochlore lattice of Os atoms, in which all the spins point to (all-in) or away (all-out) from the centers of the tetrahedron. The magnetostriction, magnetocapacitance, Voigt magnetooptic effect, and magnetic susceptibility are expected to have a term linear to the external magnetic field.

Free Research Field

構造物性