Haiming Yu

Beihang University

Abstract: Control of spin currents in a canted antiferromagnet

Controlling the spin current lies at the heart of spintronics and its applications [1]. In ferromagnets, the sign of spin currents is fixed once the current direction is determined. However, spin currents in antiferromagnets can possess opposite polarizations, but this usually requires enormous magnetic fields to lift the degeneracy between the two modes. Therefore, controlling spin currents with opposite polarization is still a challenge.

In this talk, I will present our recent work demonstrating the control of spin currents at room temperature by magnon interference in a canted antiferromagnet hematite [2]. Magneto-optical characterization by Brillouin light scattering reveals that the spatial periodicity of the beating patterns is tunable via the microwave frequency. We further observe that the inverse spin Hall voltage changes sign as the frequency is tuned, evincing a frequency-controlled switching of polarization of pure spin currents. Our work highlights the use of antiferromagnetic magnon interference to control spin currents, which substantially extends the horizon for the emerging field of coherent antiferromagnetic spintronics [3].

Figure 1: The inverse spin-Hall voltages () probed by a Pt bar on hematite as a function of the applied magnetic field and excitation microwave frequency. The blue and red colors represent positive and negative ISHE voltages, respectively. The alternating sign of exhibit the oscillation between right-handed and left-handed spin current originated from magnon interference in the canted antiferromagnet.

References:
[1] S. Maekawa, S. O. Valenzuela, E. Saitoh, and T. Kimura, Spin Current (Oxford University Press, Oxford, 2017).
[2] L. Sheng, A. Duvakina, H. Wang, K. Yamamoto, R. Yuan, J. Wang, P. Chen, W. He, K. Yu, Y. Zhang, J. Chen, J. Hu, W. Song, S. Liu, X. Han, D. Yu, J.-Ph. Ansermet, S. Maekawa, D. Grundler and H. Yu, Control of spin currents by magnon interference in a canted antiferromagnet. Nat. Phys. 21, 740-745 (2025).
[3] J. Han, R. Cheng, L. Liu, H. Ohno and S. Fukami, Coherent antiferromagnetic spintronics. Nat. Mater. 22, 684-695 (2023).