Magnetic Amplification at Yb3+ "Designer Defects" in the van der Waals Ferromagnet CrI3

Kimo Pressler; Thom J Snoeren; Kelly M Walsh; Daniel R Gamelin

doi:10.1021/acs.nanolett.2c04533

Magnetic Amplification at Yb³⁺ "Designer Defects" in the van der Waals Ferromagnet CrI₃

Nano Lett. 2023 Feb 22;23(4):1320-1326. doi: 10.1021/acs.nanolett.2c04533. Epub 2023 Feb 1.

Authors

Kimo Pressler¹, Thom J Snoeren¹, Kelly M Walsh¹, Daniel R Gamelin¹

Affiliation

¹ Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.

PMID: 36724213
DOI: 10.1021/acs.nanolett.2c04533

Abstract

The two-dimensional (2D) van der Waals ferromagnet CrI₃ has been doped with the magnetic optical impurity Yb³⁺ to yield materials that display sharp multiline Yb³⁺ photoluminescence (PL) controlled by the magnetism of CrI₃. Magneto-PL shows that Yb³⁺ magnetization is pinned to the magnetization of CrI₃. An effective internal field of ∼10 T at Yb³⁺ is estimated, attributed to strong in-plane Yb³⁺-Cr³⁺ superexchange coupling. The anomalously low energy of Yb³⁺ PL in CrI₃ reflects relatively high Yb³⁺-I^- covalency, contributing to Yb³⁺-Cr³⁺ superexchange coupling. The Yb³⁺ PL energy and line width both reveal the effects of spontaneous zero-field CrI₃ magnetic ordering within 2D layers below T_C, despite the absence of net magnetization in multilayer samples. These results illustrate the use of optical impurities as "designer defects" to introduce unique functionality to 2D magnets.

Keywords: 2D ferromagnet; chromium triiodide; lanthanide doping; molecular field; photoluminescence.