Scientists discover a novel, light-induced magnetic state
Scientists discover a novel, light-induced magnetic state
Magnetism arises from diverse patterns of electron spin, which refers to the property of electrons that essentially causes them to act as tiny magnets. A material’s magnetic properties are classified depending on the alignment of these spins and net magnetization. To name a couple, there are ferromagnets with aligned spins and non-zero net magnetization, and antiferromagnets with anti-aligned spins that cancel out and give zero net magnetization. Exploring novel ways to control electron spin is a major objective in the innovation of technologies like memory devices.
A recent study from MIT demonstrated a new way to tune magnets. Unlike traditional methods of controlling spin with external current, this study utilizes a terahertz light pulse to change the patterns of spin alignment inside the material. According to the study, the light pulse results in non-zero magnetization in an iron-based semiconductor, FePS3, which is otherwise an antiferromagnet with zero net magnetization. The light pulse magnetizes the material by changing the energy states of particles, causing them to vibrate in a crystal-like grid, changing the distances between atoms. The change in atomic distance changes how spins nearby interact with each other, or spin-spin interaction, changing the antiparallel alignment of the original antiferromagnetic state.
The lifetime for which this emergent magnetic state is stable substantially exceeds the timescale of usual spin-spin interactions, unlike previous studies that showed light-induced magnetism for only about a few hundred picoseconds. This implies that the newly discovered magnetic state might be stable enough to be implemented in new technologies and other conventional experimental techniques with long timescales. This novel strategy for light-induced magnetism may open the doors to next-generation memory devices.
This study was led by Batyr Ilyas, Nuh Gedik et al. from MIT, US.
Managing Correspondent: Seunghyun (Elizabeth) Park
Press Article: MIT’s light-activated antiferromagnetic memory could replace today’s ferromagnets (Techspot)
Original Journal Articles: Terahertz field-induced metastable magnetization near criticality in FePS3 (Nature)
Image Credit: pixabay/Placidplace