Giant enhancement of interlayer exchange in an ultrathin 2D magnet

• Published in: arXiv.org
• Main Authors: Klein, Dahlia R, MacNeill, David, Song, Qian, Larson, Daniel T, Shiang Fang, Xu, Mingyu, Ribeiro, R A, Canfield, Paul C, Kaxiras, Efthimios, Comin, Riccardo, Jarillo-Herrero, Pablo
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 28.02.2019
• Subjects: Antiferromagnetism; Crystallography; Crystals; Deformation; Electron tunneling; Exchanging; Exfoliation; Ground state; Heterostructures; Interlayers; Magnetic materials; Magnetism; Magnets; Phase transitions; Physics - Materials Science; Physics - Mesoscale and Nanoscale Physics; Raman spectroscopy; Ruthenium trichloride; Spintronics; Stacking faults; Temperature dependence
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1903.00002

Following the recent isolation of monolayer CrI3, there has been a surge of new two-dimensional van der Waals magnetic materials, whose incorporation in van der Waals heterostructures offers a new platform for spintronics, proximity magnetism, and quantum spin liquids. A primary question in this burgeoning field is how exfoliating crystals to the few-layer limit influences their magnetism. Studies on CrI3 have shown a different magnetic ground state for ultrathin exfoliated films but the origin is not yet understood. Here, we use electron tunneling through few-layer crystals of the layered antiferromagnetic insulator CrCl3 to probe its magnetic order, finding a ten-fold enhancement in the interlayer exchange compared to bulk crystals. Moreover, temperature- and polarization-dependent Raman spectroscopy reveal that the crystallographic phase transition of bulk crystals does not occur in exfoliated films. This results in a different low temperature stacking order and, we hypothesize, increased interlayer exchange. Our study provides new insight into the connection between stacking order and interlayer interactions in novel two-dimensional magnets, which may be relevant for correlating stacking faults and mechanical deformations with the magnetic ground states of other more exotic layered magnets, such as RuCl3.