High field study of quantum magnets through measurements of magnetoelectric effects

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K05413
• 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: The University of Tokyo
• Principal Investigator: Tokunaga Masashi 東京大学, 物性研究所, 准教授 (50300885)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: マルチフェロイクス / 磁性

Outline of Final Research Achievements

Multiferroic materials have attracted considerable attentions due to their possible application for magnetoelectric memory devices. BiFeO3 is perhaps the most extensively studied multiferroic material because it exhibits prominent mutiferroic properties at room temperature, In this study, we developed study about non-volatile memory effects in this material, and realized this phenomenon in the ferromagnetic and ferroelectric state. We also clarified microscopic origin for this effect.
In the study of Ba2CuGe2O7, we studied magnetoelectric effects and ultrasound transmission in high magnetic fields. Through these experiments, we clarified field control of hybridization between Cu 3d and O 2p orbitals plays a key role in the magnetoeectric effect even in this quantum spin magnet.

Free Research Field

強磁場物性

Academic Significance and Societal Importance of the Research Achievements

マルチフェロイック物質における電気磁気効果は、物質の新しい可能性を開くテーマとしてこの２０年ほど盛んに研究されてきた。本研究ではこの分野で長年追い求められてきた強磁性と強誘電性の共存状態における電気磁気メモリー効果の実証に成功した。またこの現象の微視的起源である磁性イオンと周囲の配位子イオンとの軌道混成の磁場制御は、単純な理論予測に反してスピンの短い量子スピン系でも観測されている。この現象の代表的物質に対して強磁場下の電気磁気効果と超音波伝導の実験を行うことで、その微視的起源を明らかにした。