Magnetic influence on phonon frequencies in two-dimensional FeOCl: Insights from spin-phonon coupling

The coupling of phonon with spin in two-dimensional (2D) materials provides valuable insights into anomalous phonon behaviors. However, studies on spin-phonon coupling (SPC) in antiferromagnetic (AFM) materials are still in their preliminary stages. In this work, based on the first-principles calculations, we investigate the influence of spin ordering on phonon properties in 2D FeOCl, considering both ferromagnetic and four AFM configurations. Results based on the Raman scattering calculations and second-order SPC analysis demonstrate a strong magnetic dependence in phonon behaviors, which has a maximum frequency shift of 7.40 cm(-1). Such a shift is considerably large when compared to other 2D materials such as graphene and MoS2, which are typically around 3-5 cm(-1). We also analyze the frequency difference between neighboring Ag Raman peaks for different magnetic configurations, which shows a distinct change of about 18.8 cm(-1). Furthermore, we explore the relationship between the frequency of Raman peaks and magnetic exchange interactions under uniaxial strains. Within the strain range from -3% to 3%, an increment in strain leads to a decrement in both phonon frequency and magnetic exchange interactions. Our findings contribute to a deeper understanding of SPC in 2D FeOCl, and establish a solid theoretical foundation for further exploration in spintronics.