Doping and Nanostructuring Two-Dimensional Magnets
Daniel Gamelin a, Kimo Pressler a, Thom Snoeren a, Kelly Walsh a
a Department of Chemistry, University of Washington, Seattle, WA, 98195-1700, USA
Proceedings of International Conference on Emerging Light Emitting Materials (EMLEM23)
Peyia, Cyprus, 2023 November 13th - 15th
Organizers: Grigorios Itskos, Maksym Kovalenko and Maryna Bodnarchuk
Invited Speaker, Daniel Gamelin, presentation 035
Publication date: 18th August 2023

This talk will describe our group's recent work on controlling the spin-photonic properties of magnetic van der Waals materials through synthesis, doping, and dimensional reduction. In one approach, the CrX3 (X = Cl, Br, I) family of two-dimensional (2D) ferromagnets have each been doped with the optical impurity Yb3+ to yield new, narrow-line lanthanide photoluminescence (PL) sensitized by CrX3. Magneto-PL is used to probe Yb3+ magnetization and its relationship to that of the host CrX3, and reveals extremely large exchange fields arising from strong in-plane Yb3+-Cr3+ superexchange coupling. Spectral analysis indicates anomalously high covalency in Yb3+-doped CrI3, providing insight into the microscopic origins of the strong Yb3+-Cr3+ superexchange coupling. In a second approach, CrX3 is prepared as colloidal nanoplatelets to probe the effects of dimensional reduction on TC and magneto-optical response, revealing robust single-domain ferromagnetism down to domain diameters of ca. 20 nm x 3 nm, along with dramatically enhanced coercivity relative to bulk. These results illustrate the use of optical impurities and dimensional reduction as tools for manipulating the spin-photonic properties of metal-halide 2D magnets.

Support of this project by the US NSF (DMR-1807394) is gratefully acknowledged. Additional support was received from the UW Clean Energy Institute (graduate fellowships). Part of this work was conducted at the Molecular Analysis Facility, a National Nanotechnology Coordinated Infrastructure (NNCI) site at the University of Washington that is supported in part by the National Science Foundation (NNCI-1542101 and NNCI-2025489), the University of Washington, the Molecular Engineering & Sciences Institute, the Clean Energy Institute, and the National Institutes of Health. EXAFS measurements were supported by the UW Molecular Engineering Materials Center, an NSF Materials Research Science and Engineering Center (Grant No. DMR-1719797). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

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