Photoluminescence and Raman Enhancement by Edge Plasmons in MnPS₃

Abstract

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 MnPS 3 , which are attributed to the near-field edge plasmon antenna enhancement in few hundred nm thick flakes. We observed two in-gap nearinfrared emission signals and studied their thickness dependence. For the first time, we performed tip-enhanced photoluminescence (TEPL) imaging of MnPS 3 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 MnPS 3 via tunneling-induced PL suppression, revealing a 300 nm wide edge plasmon size. Our work opens new possibilities for plasmonic applications of MnPS 3 , while quantum plasmonic imaging may be used to discover novel plasmonic materials.