Quantum-Confined Tunable Ferromagnetism on the Surface of a Van der Waals Antiferromagnet NaCrTe<sub>2</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 39101565.
- Also identified by DOI 10.1021/acs.nanolett.4c01542.
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Abstract
The surface of three-dimensional materials provides an ideal and versatile platform to explore quantum-confined physics. Here, we systematically investigate the electronic structure of Na-intercalated CrTe<sub>2</sub>, a van der Waals antiferromagnet, using angle-resolved photoemission spectroscopy and <i>ab initio</i> calculations. The measured band structure deviates from the calculation of bulk NaCrTe<sub>2</sub> but agrees with that of ferromagnetic monolayer CrTe<sub>2</sub>. Consistently, we observe unexpected exchange splitting of the band dispersions, persisting well above the Néel temperature of bulk NaCrTe<sub>2</sub>. We argue that NaCrTe<sub>2</sub> features a quantum-confined 2D ferromagnetic state in the topmost surface layer due to strong ferromagnetic correlation in the CrTe<sub>2</sub> layer. Moreover, the exchange splitting and the critical temperature can be controlled by surface doping of alkali-metal atoms, suggesting the feasibility of tuning the surface ferromagnetism. Our work not only presents a simple platform for exploring tunable 2D ferromagnetism but also provides important insights into the quantum-confined low-dimensional magnetic states.