Harnessing Topological Materials for Energy-Efficient Spintronics and Terahertz Devices

Abstract

Topological quantum materials have emerged as pivotal components in high-speed spintronic devices, operating from gigahertz (GHz) to terahertz (THz) frequencies. Their nontrivial topological electronic state exhibits the exotic spin-momentum locking property, which can facilitate highly efficient interconversion between spin and charge currents. This capability is central to two primary and promising applications. Firstly, it enables the deterministic and energy-efficient switching of magnetization in adjacent magnetic layers with remarkably low current densities. This mechanism is important for developing next-generation, low-power magnetic memory, and ultrafast logic devices. Secondly, heterostructures integrating topological materials with magnetic layers have demonstrated exceptional performance in THz photonics. These systems function as efficient emitters of broadband THz radiation driven by ultrafast spin current generation and subsequent conversion into charge currents upon photoexcitation using femtosecond lasers. Conversely, their pronounced inverse spin Hall effect and sensitivity to spin currents also make them compelling candidates for novel solid-state THz detection. Together, these capabilities position topological materials as a unified platform that simultaneously lowers the energy cost of memory and logic devices, as well as enables broadband THz generation and detection, opening new avenues for spintronics. This Review emphasizes experimentally demonstrated spintronic and THz functionalities, device-relevant operating conditions, and representative mechanisms.