Photoluminescence and Raman Enhancement by Edge Plasmons in MnPS3

Unconventional plasmonic materials beyond traditional noble metals extend applications of nanotechnology to novel optical, electrical, and magnetic devices. For example, the low photoluminescence (PL) efficiency of two-dimensional (2D) magnetic materials hinders their effective utilization in magnetooptical studies and practical applications, despite their significant role in information storage and spintronic devices. Plasmon-enhanced PL is a promising route toward efficient magneto-optical applications. Here, we report the first observations of enhanced PL and Raman signals in a multilayered 2D antiferromagnet MnPS3, which are attributed to the near-field edge plasmon antenna enhancement in few hundred nm thick flakes. We observed two in-gap near-infrared emission signals and studied their thickness dependence. For the first time, we performed tip-enhanced photoluminescence (TEPL) imaging of MnPS3 in classical (tapping mode) and quantum plasmonic (contact mode) regimes. Classical TEPL showed signal enhancement via plasmonic gap-mode and surface guided waves. Quantum plasmonic TEPL showed evidence for edge plasmons in MnPS3 via tunneling-induced PL suppression, revealing a 300 nm wide edge plasmon size. Our work opens new possibilities for plasmonic applications of MnPS3, while quantum plasmonic imaging may be used to discover novel plasmonic materials.