Characterization of morphological, electronic and magnetic properties of α−Mn surfaces*

The α-manganese phase has one of the most complex and unique crystal structures among all metals in the periodic table with a 58 atom basis and a non-collinear antiferromagnetic bulk spin-structure. Manganese is a cornerstone magnetic material for a variety of applications: in dilute magnetic semiconductors, as a rare-earth free magnet, and in magnetic topological insulators to name a few. Despite its prevalence in applied materials as an alloy, little real-space investigations of α-Mn have been performed. We performed a thorough analysis of the surface structures of α-Mn via first principles and scanning tunneling microscopy (STM). We present the most stable surface reconstructions and a description of the atomic arrangements at the surface as showcased by both theoretical and experimental STM images. Analysis of real-space and Fourier transformed STM images help match candidate Terrsoff-Hamann simulation surfaces with experimental STM images. Analysis of electronic band structure and magnetic spin-structures reveals a non-collinear spin structure. Finally, a discussion of the mechanisms that lead to the difference in bulk and surface properties is presented.