Relation between crystal structure and optical properties in the correlated blue pigment YIn1-xMnxO3

A material's properties and functionalities are determined by its chemical constituents and the atomic arrangement in which they crystallize. For the recently discovered pigment YIn1-xMnxO3, for instance, it had been surmised that its bright blue color owes to an unusual, trigonal bipyramidal, oxygen coordination of the manganese impurities. Here, we demonstrate that, indeed, a direct correspondence between details of the local Mn environment and the pigment's blue color holds: Combining realistic many-body calculations (dynamical mean-field theory to treat the quasi-atomic Mn-multiplets at low doping x=8%) with an effective medium description (Kubelka-Munk model to describe scattering in a milled pigment sample), we find that only a Mn-coordination polyhedra consisting of two distorted oxygen pyramids results in a diffuse reflectance commensurate with the experimental blue color. We motivate that the distortion of the bipyramid helps circumventing atomic selection rules, allowing for dipolar d-d transitions and creating the desired two-peak absorption profile.