Yingxi Bai

1 Introduction Magnetic excitations play a pivotal role in revealing the fundamental spin dynamics and underpin the design of next-generation magnonic devices [1-5]. Compared with conventional ferromagnetic (FM) magnons [6-13], antiferromagnetic (AFM) magnons possess compensated antiparallel spins that eliminate net magnetization, thereby exhibiting ultrafast spin dynamics, robustness against external magnetic fields, and the absence of stray fields [14-22].

Abstract Click to copy section linkSection link copied! Recent advances in manipulating orbital degrees of freedom in electronic systems have sparked interest in the novel field of orbitronics, emphasizing the need to integrate it with existing spintronic paradigms in next-generation devices. Here, we outline the principle of quantum orbital-to-spin conversion, a mechanism that converts the quantized orbital Hall effect into the quantum spin Hall effect by ferroelectricity.

Magnetic topological insulators have been attracting great interest in two dimensions for both fundamental physics and applications in spintronics. Here, we put forward that the topological phase transition between a second-order topological insulator and quantum anomalous Hall insulator with a strikingly different bulk-boundary correspondence is possible in two-dimensional ferromagnets.