Study of interplay between magnetic/electric fields and Cr-doped effect in Mo_1-xCr_xSe₂ (x=0, 0.5) nanosheet

This study investigated the effects of Cr-doping on 2D MoSe ₂ nanosheets and the interplay between external magnetic and electric fields. The introduction of Cr ions as substitutes for Mo ions causes a transition from diamagnetism to paramagnetism in MoSe ₂ , and vacancies at the Mo site in pure MoSe ₂ also result in paramagnetism below 10 K. The A _1g mode of Raman spectra shows two characteristic temperatures, T _a and T _b at 150 K and 210 K, respectively, for x=0, and T _a ’ and T _b ’ at 180 K and 260 K, respectively, for x=0.5. These anomalies disappear when an external magnetic field is applied, indicating that the vibration mode along the c -axis is magnetic sensitive. In contrast, the subjection of an external electric field does not display a similar effect in the Cr-doped sample. However, the peak width of pure MoSe ₂ gradually broadens as the external electric field increases and does not narrow again upon removal of the field. These observations suggest that smaller Cr ions reduce the interplane distance and enhance the coupling strength along the c -axis, which resists the influence of an external electric field and increases the characteristic temperatures in the A _1g mode.