Bi1.9Mn0.1Te3 nanocrystal functionalized diamagnetic glasses: optical, luminescence, magnetic and Faraday rotation

Abstract Mn doped Bi2Te3 nanocrystal, both as topological insulator and diluted magnetic semiconductor, has gained significant interest due to its interesting magnetic performance roused by the sp-d exchange interaction and unique time-reversal symmetry protected surface states. In this paper, for the first time, Bi1.9Mn0.1Te3 nanocrystal doped diamagnetic TeO2–PbO–B2O3 glass was studied. Pure 50nm hexagonal Bi1.9Mn0.1Te3 nanocrystals were synthesized with a specific surface area of 64.28 m2/g using the optimized PEG as surfactant. Due to the complex spin-orbit interactions between sp band of Bi2Te3 and d band of Mn, the prepared Bi1.9Mn0.1Te3 displayed characteristic luminescence, A11g, E2g, A21g Raman modes, good photocatalytic (70.2%) and ferromagnetic/paramagnetic co-existence behavior. Bi1.9Mn0.1Te3 doped diamagnetic glasses were prepared by melting-quenching technique and the influence of different doping amount to glass structure and properties was evaluated through X-ray diffraction, Fourier transforms infrared, Raman, Ultraviolet-visible, photoluminescence spectra and Verdet constant measurement. The glasses structure and properties were doping amount dependent. X-ray diffraction, Fourier transforms infrared and Raman spectra revealed the evolution of structure units of TeO4, TeO3, BO3 etc under the modification of Bi1.9Mn0.1Te3. SEM revealed the homogeneity and growth of nanocrystals in matrix. X-ray photoelectron spectroscopy displayed the chemical states changes of Mn2p, Bi4f, Te3d and O1s under different doping amounts. Both the optical absorption band at 540nm and cutoff wavelength increased with the dopant amount. The luminescence in visible range revealed the tetrahedral coordination state of paramagnetic Mn ions which also influenced the magnetization and Faraday rotation accordingly. Experimental results showed that glass with 2%Bi1.9Mn0.1Te3 exhibited good optical, luminescence, magnetic, significant high Verdet constant (0.2522min/G.cm) and good thermal stability as well. Such good quality diamagnetic glass is attractive for magneto-optical devices applications in isolator and current transducer etc.