High-resolution angle-resolved photoemission spectroscopy with tunable magnetic field.

The control and perturbation of quantum phenomena with magnetic fields is an indispensable tool in materials research. Recently, in situ field tuning was implemented into angle-resolved photoemission spectroscopy (magneto-ARPES), which provides direct momentum and energy-resolved information of the field-dependent electronic structure. However, aberrations of the electron trajectories were shown to be substantial, leading to significant spectral distortions and broadening even in small fields. Here, we show that the electronic structure can be recovered from magneto-ARPES spectra with high accuracy while maintaining high momentum resolution even when strong trajectory aberrations are present. We studied Bi2Se3 in a dipole field of a coil using a laser-based ARPES system. The electronic structure was reconstructed in post-processing using detailed electron trajectory simulations. We identify two-dimensional momentum mapping, a micron beam spot size, and precise numerical field simulations as critical technical requirements for high-resolution magneto-ARPES. We show how circular dichroism can provide additional information about the coupling of the magnetic field to the spin. The experimental achievements and the scaling laws from our simulations provide a road map toward magneto-ARPES in larger fields.