Direct Observation of sp-d Exchange Interaction in Mn$^2$$^+$doped All-inorganic Perovskite Quantum Dots (CsPbX$_3$: X= Cl, Br)

The field of lead halide perovskite nanocrystal doping has witnessed notable progress in recent times, leading to the creation of innovative materials that showcase compelling physical characteristics and hold substantial technological promise. The true characteristics of these materials lie in the presence of dopant-carrier magnetic exchange interactions. This work presents the first direct observation of such exchange interactions in colloidal Mn-doped CsPbX$_3$ (X= Cl, Br) quantum dots (QDs). Here, we employ magnetic circular dichroism (MCD) spectroscopy to unambiguously demonstrate the successful doping and the presence of giant excitonic Zeeman splitting in CsPbX$_3$ (X= Cl, Br) QDs doped with Mn$^2$$^+$. The controllable tuning of effective exciton g-factors (g$_e$$_f$$_f$) within the range of 2.1 to (-)314 has been achieved through the process of doping with 6.9 % Mn in CsPbCl$_3$, which will facilitate their application towards future spintronics