(Invited) Manipulating the Exotic Excitons of Van Der Waals Correlated Antiferromagnet with Impurities and Size

Abstract

A Van der Waals correlated antiferromagnet, metal phosphorus trichalcogenides (MPX3, M = Mn, Fe, Ni; X = S, Se), have emerged as promising candidates for next generation spintronics, and quantum information technologies. Nickel phosphorus trisulfide (NiPS3) is a most notable member of this family and has been extensively studied for its unique properties, including the emergence of an ultra-sharp photoluminescence (PL) peak at ~1.476 eV below Néel temperature of 150 Kelvin. While the highly anisotropic, linearly polarized emission of this PL peak has been shown to be directly correlated to the long-range spin order of NiPS3, its ultra-narrow linewidth of a few hundred meV has led to the speculation that it is originated from a coherent many-body exciton state. Observations of multiple phonon bounds states and formation of exciton-polaritons also creates more excitement as they present new possibilities for design and control of correlated electron systems.Aiming to achieve understanding and control of this spin-correlated exciton, we conduct temperature dependent, polarization resolved, PL studies on compounds of NiPS3 doped with different concentration of Mn (Ni1-xMnxPS3) and Se (NiPS3(1-x)Se3x). We observed systematic variation in characteristics of the spin-correlated exciton revealing their sensitive dependence on disturbance in the magnetic order of NiPS3.Next, to explore the effect of nanostructuring, we developed a novel chemical synthesis for highly crystalline NiPS3 nano flakes. We observed an activation of a new exciton state that share many exciting properties of bulk spin-correlated exciton.