Chemical Vapor Deposition and Raman Spectroscopy of Two-Dimensional Antiferromagnetic FeOCl Crystals
Ziyue Qian, Zhigang Song, Juanxia Wu, Dongwei Wang, Wen Wen, Xinsheng Wang, Ying Liu, Liming Xie
Abstract
Chemical vapor deposition (CVD) and probing magnetic properties of atomically thin two-dimensional (2D) materials are of great interest for future information devices. Here, we report a CVD growth of 2D FeOCl crystals and a Raman spectroscopic study of the magnetic phase transition. 2D FeOCl crystals with different thicknesses have been grown on mechanically exfoliated h -BN by using KMnO 4 and FeCl 3 as precursors. Raman scattering has been conducted on the chemically grown FeOCl thin crystals, which can probe the magnetic orderings in various ways, such as quasi-particle scattering, quasi-elastic scattering (QES), magneto-optical effect, and so on. Under an external magnetic field, the A g phonon modes have shown a linear relationship of B /ρ to B 2 ( B is the external magnetic field and ρ is the degree of Raman circular polarization), which supports the calculated magnetic point group of m ′ m ′ m in FeOCl thin crystals below T N . Other magnetic Raman features, including quasi-elastic scattering and two-magnon scattering, have been observed, which gives information about the magnetic specific heat and magnetic excitations, respectively. At last, temperature-dependent and thickness-dependent Raman spectroscopic measurements have shown a robust paramagnetic–antiferromagnetic (PM–AFM) phase transition in FeOCl thin crystals.