The photoelectron momentum microscope—a hybrid system comprising a photoelectron emission microscope, an energy analyzer, and a projection-type two-dimensional detector—represents a paradigm shift in materials characterization. This system facilitates the simultaneous acquisition of constant-energy two-dimensional photoelectron intensity distributions, permitting high-resolution visualization of real-space microscopic images with elemental, chemical, and structural selectivity. Concurrently, it provides access to reciprocal-space electronic structures, such as Fermi surfaces and valence band dispersions, from selected localized regions. A key advantage of this methodology lies in the snapshot acquisition of spin-polarized two-dimensional distributions, owing to the seamless integration of the projection-type analyzer with a spin filter. Originating in Germany, this technology has seen increasing adoption worldwide in recent years. In Japan, systems have been introduced at several institutions, where characteristic research is beginning to unfold. This article reviews the current capabilities and future challenges of spin measurements using this advanced instrumentation.
Matsui et al. (Thu,) studied this question.