Tuning magnetic and optical properties in Mn_xZn_1−xPS₃ single crystals by the alloying composition

The exploration of two-dimensional (2D) antiferromagnetic (AFM) materials has shown great promise and interest in tuning the magnetic and electronic properties as well as studying magneto-optical effects. The current work investigates the control of magneto-optical interactions in alloyed Mn _x Zn_1−xPS₃ lamellar semiconductor single crystals, with the Mn/Zn ratio regulating the coupling strength. Magnetic susceptibility results show a retention of AFM order followed by a decrease in Néel temperatures down to ∼40% Mn concentration, below which a paramagnetic behavior is observed. Absorption measurements reveal an increase in bandgap energy with higher Zn(II) concentration, and the presence of Mn(II) d-d transition below the absorption edge. DFT + U approach qualitatively explained the origin and the position of the experimentally observed mid band-gap states in pure MnPS₃, and corresponding peaks visible in the alloyed systems Mn _x Zn_1‒xPS₃. Accordingly, emission at 1.3 eV in all alloyed compounds results from recombination from a ⁴T_1g Mn(II) excited state to a hybrid p-d state at the valence band. Most significant, temperature-dependent photoluminescence (PL) intensity trends demonstrate strong magneto-optical coupling in compositions with x > 0.65. This study underscores the potential of tailored alloy compositions as a means to control magnetic and optical properties in 2D materials, paving the way for advances in spin-based technologies.