Antiferromagnetic spintronics is an emerging research field which aims to utilize antiferromagnets as core elements in spintronic devices^1,2. A central motivation towards this direction is that antiferromagnetic spin dynamics is expected to be much faster than its ferromagnetic counterpart³. Recent theories indeed predicted faster dynamics of antiferromagnetic domain walls (DWs) than ferromagnetic DWs^4,5,6. However, experimental investigations of antiferromagnetic spin dynamics have remained unexplored, mainly because of the magnetic field immunity of antiferromagnets⁷. Here we show that fast field-driven antiferromagnetic spin dynamics is realized in ferrimagnets at the angular momentum compensation point T_A. Using rare earth–3d-transition metal ferrimagnetic compounds where net magnetic moment is nonzero at T_A, the field-driven DW mobility is remarkably enhanced up to 20 km s⁻¹ T⁻¹. The collective coordinate approach generalized for ferrimagnets⁸ and atomistic spin model simulations^6,9 show that this remarkable enhancement is a consequence of antiferromagnetic spin dynamics at T_A. Our finding allows us to investigate the physics of antiferromagnetic spin dynamics and highlights the importance of tuning of the angular momentum compensation point of ferrimagnets, which could be a key towards ferrimagnetic spintronics.

反铁磁自旋电子学是一个新兴的研究领域，旨在利用反铁磁作为自旋电子器件^1,2的核心元素。朝这个方向发展的主要动机是，反铁磁自旋动力学有望比其铁磁自旋动力学更快³。最近的理论确实预测比铁磁DW ^4,5,6更快的反铁磁畴壁（DWs）动力学。然而，反铁磁自旋动力学的实验研究仍未探索，主要是因为反铁磁⁷的磁场抗扰性。在这里，我们表明，在角动量补偿点T处，在ferrimagnets中实现了快速的场驱动反铁磁自旋动力学_一。使用在T _A处净磁矩不为零的稀土3d过渡金属亚铁化合物，在高达20 km s ^-1  T ^{-1的范围内}，场驱动的DW迁移率显着提高。对于铁氧体⁸和原子自旋模型仿真^6,9的通用集合坐标方法表明，这种显着增强是在T _A时反铁磁自旋动力学的结果。我们的发现使我们能够研究反铁磁自旋动力学的物理原理，并强调了调整铁氧体的角动量补偿点的重要性，这可能是通向铁磁自旋电子学的关键。