Angle-resolved photoemission spectroscopy and its application to topological materials

Angle-resolved photoemission spectroscopy (ARPES) - an experimental technique based on the photoelectric effect - is arguably the most powerful method for probing the electronic structure of solids. The past decade has witnessed notable progress in ARPES, including the rapid development of soft-X-ray ARPES, time-resolved ARPES, spin-resolved ARPES and spatially resolved ARPES, as well as considerable improvements in energy and momentum resolution. Consequently, ARPES has emerged as an indispensable experimental probe in the study of topological materials, which have characteristic non-trivial bulk and surface electronic structures that can be directly detected by ARPES. Over the past few years, ARPES has had a crucial role in several landmark discoveries in topological materials, including the identification of topological insulators and topological Dirac and Weyl semimetals. In this Technical Review, we assess the latest developments in different ARPES techniques and illustrate the capabilities of these techniques with applications in the study of topological materials. Angle-resolved photoemission spectroscopy (ARPES) is a tool for directly probing the electronic structure of solids and has had a crucial role in studying topological materials. In this Technical Review, we discuss the latest developments of various ARPES techniques and their applications to topological materials Key pointsTopological materials are characterized by non-trivial bulk and surface electronic states, which can be detected and distinguished by angle-resolved photoemission spectroscopy (ARPES).Synchrotron-based vacuum ultraviolet and soft-X-ray light make it possible to distinguish surface and bulk states through photon-energy-dependent ARPES measurements.The integration of spin detectors into ARPES photoelectron spectrometers enables the detection and quantification of spin polarization in band structures.Time-resolved ARPES with femtosecond laser pulses facilitates the study of ultrafast electronic dynamics and states above the chemical potential.Spatially resolved ARPES with sub-micrometre spatial resolution can be used to probe the electronic structure of microscale and nanoscale materials as well as materials with phase separation or multiple domains.