Investigations of spin textures at small length and short timescales with neutron, x-ray, and optical methods.

The theoretical prediction, experimental discovery, and validation of the electron spin 100 years ago have provided the scientific foundation toward a fundamental understanding of magnetism. The interactions among spins and their arrangements into spin textures at the microscopic scale and their dynamical behavior across multiple timescales largely determine the properties and behavior of magnetic materials and their functionalities in technological applications. Experimental investigations of spin textures at scientifically and technologically relevant small length and ultrashort timescales, down to nanometers and femtoseconds, respectively, have stimulated and benefited from advances in developing experimental probes using neutrons, x-rays, and optical methods. On the occasion of the centennial anniversary of the electron spin, here, we review pioneering and groundbreaking scientific accomplishments with these methods, describe the current state of the art, and provide a perspective into future directions, such as quantum information systems or neuromorphic computing, which leverage the coherence and correlations between electron spins.