Manipulation of chiral magnetic order by interfacial magnetic coupling

Noncollinear (NCL) and noncoplanar (NCP) antiferromagnets (AFMs) as well as altermagnets have attracted much attention for their potential to replace ferromagnets and to dramatically enhance the operating speed and energy efficiency, and to remove restrictions on the shape of the devices [1,2,3]. Recent intensive studies on NCL and NCP AFMs with macroscopically broken time reversal symmetry (BTRS) have solved the difficulty in controlling and detecting the AF order with a vanishingly small magnetization [2,4]. Mn₃Sn is a representative NCL AFM with BTRS and the manipulation of its chiral magnetic order have been demonstrated to date, including magnetic field control, spin orbit torque [5], and strain [6]. It is highly important to study the use of interfacial magnetic coupling with other magnetic materials as another means to control the magnetic texture. Indeed, interfacial magnetic coupling has been a key technique in spintronics and has been used to alter magnetic properties of ferromagnetic materials in various ways using different stacking sequences of materials, along with the electrical control of magnetic order and detection through tunneling magnetoresistance [7].

In this presentation, we report the manipulation of chiral AF order of the archetypical NCL AFM Mn₃Sn by interfacial magnetic coupling with other magnetic materials. We have succeeded in observing exchange bias effect through unidirectional magnetic anisotropy in Mn₃Sn which is coupled with conventional collinear AFMs [8]. Owing to its negligible shape anisotropy [3], the induced unidirectional anisotropy can be oriented omni-directionally without the influence of the demagnetizing field.

[1] Jungwirth et al., Nat. Nanotechnol. 11, 231 (2016).

[2] Nakatsuji and Arita, Annu. Rev. Condens. Matter Phys. 13, 119 (2022).

[3] Higo et al., Adv. Funct. Mater. 31, 2008971 (2021).

[4] Nakatsuji et al., Nature 527, 212 (2015).

[5] Tsai, Higo et al., Nature 508, 608 (2020); Higo, Kondou et al., Nature 607, 474 (2022).

[6] Ikhlas et al., Nat. Phys. 18, 1086 (2022).

[7] Chen, Higo, Tanaka et al., Nature 613, 490 (2023).

[8] MA et al., Adv. Mater. 36, 2400301 (2024).



*This work was partially supported by JST-Mirai (JPMJMI20A1), JST-CREST (JPMJCR18T3), JST-ASPIRE (JPMJAP2317). IQM was funded by DOE, Office of Science, BES under Award (DE-SC0019331).