Temperature-dependent Raman spectroscopic studies of spin-phonon (SP) coupling and magnon scattering in bulk and few-layer (FL) antiferromagnet (AFM) ${\text{FePS}}_{3}$ with N\'eel temperature (${T}_{N}$) $\ensuremath{\approx}$ 120 K were performed. Bulk and… Click to show full abstract
Temperature-dependent Raman spectroscopic studies of spin-phonon (SP) coupling and magnon scattering in bulk and few-layer (FL) antiferromagnet (AFM) ${\text{FePS}}_{3}$ with N\'eel temperature (${T}_{N}$) $\ensuremath{\approx}$ 120 K were performed. Bulk and FL (2--5 atomic layers) samples show four distinct modes at room temperature between 150 and $400 {\text{cm}}^{\ensuremath{-}1}$ and a broad peak at $\ensuremath{\approx}105 {\text{cm}}^{\ensuremath{-}1}$. On lowering the temperature, three distinct phenomena are observed. First, we see the SP coupling, identified by the deviation from the usual two- or three-phonon anharmonic behavior of the higher wave number peaks ($\ensuremath{\ge}150 {\text{cm}}^{\ensuremath{-}1}$) at or below ${T}_{N}$. The strength of SP coupling can be calculated for bulk and FL flakes considering mean-field approximations. Secondly, we see the spin ordering marked by the evolution of three peaks at lower wave numbers (around $105 {\text{cm}}^{\ensuremath{-}1}$) below ${T}_{N}$ due to incommensurate magnetic cells at low temperature. Thirdly, magnon excitation in FL pristine ${\text{FePS}}_{3}$ is detected by the emergence of a distinct peak at $120 {\text{cm}}^{\ensuremath{-}1}$ ($\ensuremath{\sim}3.6$ THz) at a temperature much lower than ${T}_{N}$ ($\ensuremath{\approx}60$ K). Tracking the magnon mode in the designed van der Waals heterostructures with ${\text{Bi}}_{2}{\text{Te}}_{3}$ and ${\text{Cr}}_{2}{\text{Ge}}_{2}{\text{Te}}_{6}$ reveal interfacial electron and hole transfer from ${\text{FePS}}_{3}$, respectively. Raman spectroscopy can thus predict the magnetic transition temperature of FL magnetic insulators via SP coupling, zone-boundary phonons, and magnons. Quasi-two-dimensional AFMs and their heterostructures involving different electronic and magnetic orders may be promising candidates for ultrafast magnon transport involving magnetoelastic waves.
               
Click one of the above tabs to view related content.