Electronic Raman scattering in the 2D antiferromagnet NiPS₃.

Abstract

Correlated-electron systems have long been an important platform for various interesting phenomena and fundamental questions in condensed matter physics. As a pivotal process in these systems, <i>d-d</i> transitions have been suggested as a key factor toward realizing optical spin control in two-dimensional (2D) magnets. However, it remains unclear how <i>d-d</i> excitations behave in quasi-2D systems with strong electronic correlation and spin-charge coupling. Here, we present a systematic electronic Raman spectroscopy investigation on <i>d-d</i> transitions in a 2D antiferromagnet—NiPS₃, from bulk to atomically thin samples. Two electronic Raman modes originating from the scattering of incident photons with <i>d</i> electrons in Ni²⁺ ions are observed at ~1.0 eV. This electronic process persists down to trilayer flakes and exhibits insensitivity to the spin ordering of NiPS₃. Our study demonstrates the utility of electronic Raman scattering in investigating the unique electronic structure and its coupling to magnetism in correlated 2D magnets.