Two-dimensional transitional metal halides have recently attracted significant attention due to their thickness-dependent and electrostatically tunable magnetic properties. However, this class of materials is highly reactive chemically, which leads to irreversible degradation and catastrophic dissolution within seconds in ambient conditions, severely limiting subsequent characterization, processing, and applications. Here, we impart long-term ambient stability to the prototypical transition metal halide CrI3 by assembling a noncovalent organic buffer layer, perylenetetracarboxylic dianhydride (PTCDA), which templates subsequent atomic layer deposition (ALD) of alumina. X-ray photoelectron spectroscopy demonstrates the necessity of the noncovalent organic buffer layer since the CrI3 undergoes deleterious surface reactions with the ALD precursors in the absence of PTCDA. This organic-inorganic encapsulation scheme preserves the long-range magnetic ordering in CrI3 down to the monolayer limit as confirmed by magneto-optical Kerr effect measurements. Furthermore, we demonstrate field-effect transistors, photodetectors, and optothermal measurements of CrI3 thermal conductivity in ambient conditions.

Department of Chemistry Northwestern University Evanston Illinois 60208 United States

Department of Electrical and Computer Engineering Northwestern University Evanston Illinois 60208 United States

Department of Inorganic Chemistry University of Chemistry and Technology Prague Technicka 5 166 28 Prague 6 Czech Republic

Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 United States

Department of Mechanical Engineering Northwestern University Evanston Illinois 60208 United States

Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 United States

References provided by Crossref.org

Magnetic Correlation Spectroscopy in CrSBr