2019/07/23 by Christopher M. Pasco, Ismail El Baggari, Elisabeth Bianco +2 · 1 citation
Physics and Astronomy · #cond-mat.mtrl-sci
paper · pdf · doi:10.1021/acsnano.9b04392
published as ACS Nano 2019
arxiv created 2019/07/23 · arxiv updated 2019/07/25
Incorporating magnetism into two dimensional (2D) van der Waals (VdW) heterostrutures is crucial for the development of functional electronic and magnetic devices. Here we show that Nb3X8 (X = Cl, Br) is a family of 2D layered trimerized kagomé magnets that are paramagnetic at high temperatures and undergo a first order phase transition on cooling to a singlet magnetic state. X-ray diffraction shows that a rearrangement of the VdW stacking accompanies the magnetic transition, with high and low temperature phases consistent with STEM images of the end members α-Nb3Cl8 and \beta-Nb3Br8. The temperature of this transition is systematically varied across the solid solution Nb3Cl8-xBrx (x = 0-8), with x = 6 having transitions near room temperature. The solid solution also varies the optical properties, which are further modulated by the phase transition. As such, they provide a platform on which to understand and exploit the interplay between dimensionality, magnetism, and optoelectronic behavior in VdW materials.