Magnetic Amplification at Yb<sup>3+</sup> "Designer Defects" in the van der Waals Ferromagnet CrI<sub>3</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 36724213.
- Also identified by DOI 10.1021/acs.nanolett.2c04533.
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Abstract
The two-dimensional (2D) van der Waals ferromagnet CrI<sub>3</sub> has been doped with the magnetic optical impurity Yb<sup>3+</sup> to yield materials that display sharp multiline Yb<sup>3+</sup> photoluminescence (PL) controlled by the magnetism of CrI<sub>3</sub>. Magneto-PL shows that Yb<sup>3+</sup> magnetization is pinned to the magnetization of CrI<sub>3</sub>. An effective internal field of ∼10 T at Yb<sup>3+</sup> is estimated, attributed to strong in-plane Yb<sup>3+</sup>-Cr<sup>3+</sup> superexchange coupling. The anomalously low energy of Yb<sup>3+</sup> PL in CrI<sub>3</sub> reflects relatively high Yb<sup>3+</sup>-I<sup>-</sup> covalency, contributing to Yb<sup>3+</sup>-Cr<sup>3+</sup> superexchange coupling. The Yb<sup>3+</sup> PL energy and line width both reveal the effects of spontaneous zero-field CrI<sub>3</sub> magnetic ordering <i>within</i> 2D layers below <i>T</i><sub>C</sub>, 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.