Magnetic Interactions and Lattice Distortions in Boron-Doped Cr₂O₃: A First-Principles Perspective

Magnetoelectric Cr₂O₃ is a promising candidate for electrically controlled spintronic applications. In this work, we investigate the structural, electronic, and magnetic properties of boron-doped Cr₂O₃ using first-principles calculations within the LDA+U framework. Various doping configurations – substitutional (on Cr and O sites) and interstitial – as well as multiple charge states (B⁰, B⁺¹, and B⁻¹), are systematically explored. Among these, Cr-site substitution exhibits the lowest formation energy, although O-site substitution is also thermodynamically viable under typical experimental conditions. We analyze the impact of boron incorporation on Cr spin-flip energy and magnetic anisotropy, alongside local lattice distortions induced by doping. Our results reveal the microscopic mechanisms underlying experimentally observed phenomena such as Néel temperature enhancement, transient electric polarization, spin canting, and voltage-controlled 90° Néel vector rotation in doped Cr₂O₃.