Controlling phase transition in monolayer metal diiodides XI\(_{2}\) (X: Fe, Co, and Ni) by carrier doping

• Published in: arXiv.org
• Main Author: Prayitno, Teguh Budi
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 28.07.2021
• Subjects: Antiferromagnetism; Cobalt; Doping; Electron spin; Ferromagnetism; First principles; Ground state; Iron; Monolayers; Multiferroic materials; Nickel; Phase transitions; Physics - Materials Science; Physics - Strongly Correlated Electrons; Unit cell
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2107.13287

We applied the generalized Bloch theorem to verify the ground state (most stable state) in monolayer metal diiodides 1T-XI\(_{2}\) (X: Fe, Co, and Ni), a family of metal dihalides, using the first-principles calculations. The ground state, which can be ferromagnetic, antiferromagnetic, or spiral state, was specified by a wavevector in the primitive unit cell. While the ground state of FeI\(_{2}\) is ferromagnetic, the spiral state becomes the ground state for CoI\(_{2}\) and NiI\(_{2}\). Since the multiferroic behavior in the metal dihalide can be preserved by the spiral structure, we believe that CoI\(_{2}\) and NiI\(_{2}\) are promising multiferroic materials in the most stable state. When the lattice parameter increases, we also show that the ground state of NiI\(_{2}\) changes to a ferromagnetic state while others still keep their initial ground states. For the last discussion, we revealed the phase transition manipulated by hole-electron doping due to the spin-spin competition between the ferromagnetic superexchange and the antiferromagnetic direct exchange. These results convince us that metal diiodides have many benefits for future spintronic devices.