Electronic Structure Using Powder XRD and Its Correlation with the Origin of Room-Temperature Magnetism in Cr³⁺ Doped SnO₂

The maximum entropy method-based electronic structure of co-precipitated dilute magnetic semiconducting (DMS) material Cr_xSn_1−xO₂: x = 0.025, 0.05, and 0.075 showed interstitial charge buildup of 5.52%, 16.04%, and 10.56%, respectively, which explains room-temperature magnetism. For the strongest magnetization, there must be pure, strong, polar covalent apical and mild equatorial (Cr/Sn)-O bonding without interstitial charge buildup between the atoms. Doping of Cr3+ causes antiferromagnetism due to non-collinear magnetic spin moments between regular lattice ions and interstitial ions. The sample with 2.5% dopant showed fluctuation in d^o magnetism in SnO₂, reaching a maximum magnetization of 1.427 emu/g, making it suitable for low-field dilute magnetic semiconducting applications. All the compositions show exchange anisotropy due to the ferromagnetic and antiferromagnetic interactions in the local magnetic domains of interstitial charges. Optical absorption measurements show a minimum direct allowed band gap of 1.963 eV and a direct forbidden band gap of 1.594 eV in 5% composition, useful for photo-activated semiconductor applications. The new empirical relationship between magnetism and MEM-based electronic structure is the study's highlight.