Anomalous spin-lattice coupling in a 2D antiferromagnetic semiconductor revealed by surface acoustic Rayleigh waves.

Surface acoustic Rayleigh waves in NiPS3 thin films exhibit a significant phase velocity decrease across the Néel temperature, indicating strong magnetoelastic effects in 2D antiferromagnets.

• Why it matters: Understanding how magnetic order influences lattice dynamics in van der Waals magnets is crucial for developing spintronic and phononic devices, but experimental access to low-energy acoustic modes in small samples is difficult.
• What they did: The study used Brillouin-Mandelstam scattering spectroscopy on exfoliated NiPS3 films to measure surface acoustic phonons, observing a single Rayleigh mode whose velocity drops markedly at the antiferromagnetic transition, supported by first-principles and finite-element modeling.
• The result: Findings demonstrate that microscopic exchange interactions significantly affect the macroscopic elastic properties, paving the way for magnetically tunable phononic and spintronic applications in two-dimensional antiferromagnetic semiconductors.