Coupling of Magnetic and Optical Properties in Transition Metal Phosphorous Trichalcogenide

In recent years, van der Waals magnetic materials gained a renascence of interest due to their potential implementation in modern quantum technologies. The current study focuses on the study of <i>the transition metal phosphorous tri-chalcogenides semiconductors,</i> having a general chemical formula MPX₃ (M=1^st row transition metals, X=chalcogenides). A single MPX₃ (M=transition metal, X-chalcogenide) layer comprises a honeycomb arrangement (Neel, stripe, or zigzag) of the metal ions, producing an anti-ferromagnetism (AFM). The study tackled a few scientific questions: (1) What mechanism sustains the long-range AFM, and whether the type of magnetic arrangement can be manipulated? Previous work proposed a dominancy of spin-exchange coupling among next metal neighbors. To examine this assumption, we examined the magnetic and magneto-optical properties of a benchmark compound, MnPS₃, embedded with different diamagnetic cations (e.g., Zn²⁺). The results designated a sustain of AFM, however, with a reduction of the Neel temperature with the increase of the dopant concentration, followed by a switch of a magnetic arrangement from Neel to Zigzag in layers at Mn: Zn ratio of 1:1, and a complete loss of AFM arrangement with the dominancy of Zn ions. The gradual transitions with the increase of Zn content were reflected in shifts and polarization of the magneto-PL spectrum, exposing a magnetic-optical solid correlation. (2) Do other moments (e.g., spin-orbit) dictate spin arrangement? To address this question comparison of magneto-optical properties among a few different compounds (MnPS₃, FePS₃) has been explored. The study designated a unique behavior in FePS₃ compared to the two others, exposing new magnetic phenomena that have not been demonstrated before, supposedly related to strong spin-orbit and an inversion of symmetry breaking (see attached a representative emission spectrum). A full description of the observations will be discussed at the meeting. The experimental observations were corroboration by considering the electronic properties in the framework of DFT+U studies.