らせん磁性金属の隠れた電子的極性を測り、操る～金属のマルチフェロイクス機能を実現～

2025-04-25 東京大学

らせんの巻きの向き（時計回り・反時計回り）、電子的極性、トロイダルモーメントの方向を電流で制御

＜関連情報＞

• https://www.t.u-tokyo.ac.jp/press/pr2025-04-25-002
• https://www.t.u-tokyo.ac.jp/hubfs/press-release/2025/0425/002/text01.pdf
• https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202420614

マルチフェロイック導体におけるスピンヘリシティと非相反的電荷輸送の電流制御 Current Control of Spin Helicity and Nonreciprocal Charge Transport in a Multiferroic Conductor

Daiki Yamaguchi, Aki Kitaori, Naoto Nagaosa, Yoshinori Tokura
Advanced Materials  Published: 07 April 2025
DOI:https://doi.org/10.1002/adma.202420614

Abstract

A multiferroic state with both electronic polarity (P) and magnetization (M) shows the inherently strong P–M coupling when P is induced by cycloidal (Néel-wall like) spin modulation. The sign of P is determined by the clockwise or counterclockwise rotation of spin, termed the spin helicity. Such a multiferroic state is not limited to magnetic insulators but can be broadly observed in conductors. Here, the current control of the multiferroics is reported in a helimagnetic metal YMn₆Sn₆ and its detection through nonreciprocal resistivity (NRR). The underlying concept is the coupling of the current with the toroidal moment T∼P×M∼(q̂×χv)×M as well as with the magneto-chirality χ_v · M, whereq̂ and χ_v are the unit modulation wave vector and the vector spin chirality, respectively. An enhancement of NRR is furthermore observed by the spin-cluster scattering via χ_v and its fluctuation. These findings may pave the way to an exploration of multiferroic conductors and the application of the spin-helicity degree of freedom as a state variable.