Orbital-Selective Pauli Spin Paramagnetic Susceptibility and Doping-Tunable Magnetic Response in Monolayer Honeycomb Borophene Oxide (h-B ₂ O)

The two-dimensional (2D) monolayer honeycomb borophene oxide (h-B2O), renowned for its exceptional stability, has attracted considerable attention due to its unique topological features and potential superconducting properties. In this work, we construct a tight-binding (TB) Hamiltonian based on the Py and Pz orbitals of boron atoms and, through detailed analysis of the corresponding band structure (BS) and density of states (DOS), demonstrate the metallic nature of monolayer h-B2O. Furthermore, we report for the first time the Pauli spin paramagnetic susceptibility (PSPS) of monolayer h-B2O. At room temperature (300 K), the susceptibilities χPauliPy and χPauliPz are found to be 5.3 × 10–9 and 9.5 × 10–9 (D.L.), respectively, with χPauliPz≈1.8×χPauliPy. The observed orbital anisotropy arises from differences in the DOS of the two orbitals near the Fermi level, which govern the susceptibility. Moreover, our results show that the PSPS exhibits Pauli-type behavior at low temperatures, while at higher temperatures it follows a Curie-like dependence (χ = C/T). Furthermore, we systematically examine the influence of impurity-induced disorder on PSPS in h-B2O under both n-type and p-type doping within the T-matrix approximation. In the 0–10% doping range at 300 K, the PSPS exhibits no uniform trend but displays pronounced orbital-dependent variations. For p-type doping, the total χPauli is strongly modulated by the Pz orbital, reaching a maximum at 9% doping (88.8% increase) and a minimum at 10% (25.4% decrease). In contrast, under n-type doping, the total χPauli closely follows the Py contribution, attaining its peak at 1% doping (14.3% increase) and lowest value at 10% (24.7% decrease). This tunable, doping-dependent modulation of PSPS underscores the potential of h-B2O for diverse applications, including high-sensitivity sensors, medical imaging, and data storage (via enhanced χ), as well as electromagnetic interference shielding and magnetic-field–insensitive devices (via suppressed χ).