magnetoARPES: Angle Resolved Photoemission Spectroscopy with Magnetic Field Control

Abstract: Angle-Resolved Photoemission Spectroscopy (ARPES) is a premier technique for understanding the electronic excitations in conductive, crystalline matter, in which the induced photocurrent is collected and dispersed in energy and angle of emission to reveal the energy- and momentum-dependent single particle spectral function $A(\mathbf{k},\omega)$. So far, ARPES in a magnetic field has been precluded due to the need to preserve the electron paths between the sample and detector. In this paper we report progress towards "magnetoARPES", a variant of ARPES that can be conducted in a magnetic field. It is achieved by applying a microscopic probe beam ($\lesssim$ 10 $\mu$m ) to a thinned sample mounted upon a special sample holder that generates magnetic field confined to a thin layer near the sample surface. In this geometry we could produce ARPES in magnetic fields up to around $\pm$ 100 mT. The magnetic fields can be varied from purely in-plane to nearly purely out-of-plane, by scanning the probe beam across different parts of the device. We present experimental and simulated data for graphene to explore the aberrations induced by the magnetic field. These results demonstrate the viability of the magnetoARPES technique for exploring symmetry breaking effects in weak magnetic fields.