Mode‐Selective Spin–Phonon Coupling in van der Waals Antiferromagnets

Abstract

Abstract 2D magnetic materials offer the opportunity to study and manipulate emergent collective excitations. Among these, spin–phonon coupling is one of the most important interactions correlating charge, spin and lattice vibrations. Understanding and controlling this coupling is important for spintronics applications, control of magnons and phonon by THz radiation, and for strain‐driven magnetoelastic applications. Here, a resonant mode‐selective spin–phonon coupling in several magnetic 2D metal thiophosphates (NiPS3, FePS3, CoPS3 and MnPS3) through multi‐excitation and temperature‐dependent Raman scattering measurements is uncovered. The phonon mode, which is a Raman‐active out‐of‐plane vibrational mode (∼250 cm−1 or 7.5 THz), exhibits an asymmetric Fano lineshape where its asymmetry is proportional to the spin–phonon coupling. The measurements reveal the coupling to be the highest in NiPS3, followed by FePS3 and CoPS3, and least in MnPS3. These differences are attributed to the metal–sulfur interatomic distances, which are the lowest in NiPS3, followed by CoPS3, FePS3 and MnPS3. Finally, the spin–phonon coupling is also observed in exfoliated materials, with a slight reduction between 20 and 30% in the thinnest flakes compared to the bulk crystals.

Keywords

• 2D materials
• antiferromagnet
• spin–phonon coupling
• Raman spectroscopy