Driving spin chirality by electron dynamics in laser-excited antiferromagnets

Control of spin textures and stabilisation of chiral magnetic states is typically approached using external electrical and magnetic fields but optical manipulation offers another exciting avenue to explore. Here, the authors theoretically investigate the underlying physics of laser-driven chiral magnetism highlighting the connection between the quantum evolution of electronic states and the classical spin dynamics. Despite recent successes in the area of ultrafast manipulation of magnetic order, optical generation and manipulation of complex spin textures is hindered by an insufficient theoretical understanding of underlying processes. In particular an important aspect of subtle connection between the electronic and magnetic degrees of freedom is not properly accounted for in existing theories. Here, we uncover a distinct physical mechanism for imprinting spin chirality into collinear magnets with short laser pulses. By simultaneously treating the laser-ignited evolution of electronic structure and magnetic order, we show that their intertwined dynamics can result in an emergence of quasi-stable chiral states. We find that laser-driven chirality does not require any auxiliary external fields or intrinsic spin-orbit interaction to exist, and it can survive on the time scale of nanoseconds even in the presence of thermal fluctuations, which makes the uncovered mechanism relevant for understanding various optical experiments on magnetic materials. Our findings provide a more detailed perspective of the complex interactions which occur between chiral magnetism and light.

Automated summary

The authors investigate the theoretical physics of laser-driven chiral magnetism, highlighting the connection between the quantum evolution of electronic states and the classical spin dynamics. They find that laser-driven chirality can exist and be stable on the nanosecond timescale without the need for external fields or intrinsic spin-orbit interaction.