Intercalation-Induced Near Room-Temperature Ferromagnetism in CrI3 via Synergistic Exchange Pathways

TL;DR

This paper demonstrates that atom intercalation, especially lithium, can significantly enhance the magnetic transition temperature of CrI3 to near room temperature through synergistic exchange interactions, supported by first-principles calculations and experimental data.

Contribution

It introduces a novel intercalation strategy to achieve near room-temperature ferromagnetism in CrI3, combining theoretical predictions with experimental validation.

Findings

Intercalation increases Tc of CrI3 to 286 K, close to experimental 420 K.

Synergistic superexchange and double-exchange interactions are key mechanisms.

Other intercalants like Cu and Na also raise Tc to over 240 K.

Abstract

The development of room-temperature magnetic semiconductors is critical for advancing spintronic technologies, yet van der Waals magnets like CrI3 exhibit intrinsically low Curie temperatures (Tc = 45 K). This study employs first-principles calculations to demonstrate that atom intercalation, particularly lithium (Li), dramatically enhances magnetic exchange couplings in CrI3, achieving near room-temperature ferromagnetism with a predicted Tc of 286 K-aligning with experimental reports of 420 K. The underlying mechanism involves synergistic superexchange and double-exchange interactions: intercalation reduces the |Ep-Ed| energy difference between iodine p-orbitals and chromium d-orbitals, strengthening superexchange pathways, while charge transfer induces valence mixing (e.g., Cr3+ to Cr2+, as confirmed by experimental X-ray photoelectron spectrometry data), promoting double-exchange. Theoretical predictions extend to other intercalants including Cu and Na, with Cu0.25CrI3 and Na0.25CrI3 exhibiting Tc of 267 K and 247 K, respectively, establishing a versatile strategy for designing high-Tc magnetic semiconductors. This work bridges theoretical insights with experimental validation, offering a transferable framework for intercalation-driven material design and accelerating practical spintronic device realization.