Molecular beam epitaxy growth and structure of self-assembled Bi2Se3/Bi2MnSe4 multilayer heterostructures

Abstract

We demonstrate that the introduction of an elemental beam of Mn during the molecular beam epitaxial growth of Bi _2 Se _3 results in the formation of layers of Bi _2 MnSe _4 that intersperse between layers of pure Bi _2 Se _3 . This study revises the assumption held by many who study magnetic topological insulators (TIs) that Mn incorporates randomly at Bi-substitutional sites during epitaxial growth of Mn:Bi _2 Se _3 . Here, we report the formation of thin film magnetic TI Bi _2 MnSe _4 with stoichiometric composition that grows in a self-assembled multilayer heterostructure with layers of Bi _2 Se _3 , where the number of Bi _2 Se _3 layers separating the single Bi _2 MnSe _4 layers is approximately defined by the relative arrival rate of Mn ions to Bi and Se ions during growth, and we present its compositional, structural, and electronic properties. We support a model for the epitaxial growth of Bi _2 MnSe _4 in a near-periodic self-assembled layered heterostructure with Bi _2 Se _3 with corresponding theoretical calculations of the energetics of this material and those of similar compositions. Computationally derived electronic structure of these heterostructures demonstrates the existence of topologically nontrivial surface states at sufficient thickness.

Keywords

• topological insulator
• magnetism
• band structure
• molecular beam epitaxy
• heterostructure
• quantum matter