Figure 1.

Timeline of developments in 2D magnets. Since early 2016, a few results on monolayer phosphides MPX₃ (M = Fe, Mn, Ni, Cd; X = S, Se)^1,2 and CrSiTe₃³ appeared in the literature, with results on electron tunneling in MnPS₃ also being reported.⁴ The conclusive measurements in 2017 of magnetism on CrI₃⁵ and Cr₂Ge₂Te₆⁶ sparked an increasing interest in several subjects involving magnetism in 2D. Results on spin–lattice coupling collected from CrCl₃⁷ also provided different mechanisms involving vibrations and spins in 2D. In 2018, the electric control of magnetism,⁸⁻¹² giant magnetoresistance,¹³⁻¹⁶ and a potential 2D magnet (i.e., VSe₂) displaying room-temperature magnetism¹⁷⁻¹⁹ attracted substantial interest in the community. In 2019, experimental evidence of stacking-dependent magnetic properties,^20,21 pressure effects,^22,23 and giant second-harmonic generation (SHG)²⁴ drove the field toward intriguing magnetic properties. In 2020, spin-textures²⁵⁻²⁷ such as skyrmions, spirals, and spin-waves²⁸ indicate that topologically nontrivial spins are a reality on 2D magnets. In 2021, a few reports on twisted magnetic layers,^29,30 together with the hybrid character of narrow domain-walls³¹ on CrI₃, raised possibilities for the angular control of magnetic features and domain-wall based applications (i.e., racetrack). All images adapted from the references cited above with permission as follows. Panels from (2016) reprinted with permission from ref (32), copyright 2016 American Chemical Society; ref (3), copyright 2016 Royal Society of Chemistry; ref (1), copyright 2016 American Chemical Society; and ref (4), copyright 2016 AIP Publishing and reprinted with permission under a Creative Commons Attribution (CC BY) license. Panels from (2017) reprinted with permission from ref (5), copyright 2017 Springer Nature; ref (6), copyright 2017 Springer Nature; and ref (7), copyright 2017 American Physical Society. Panels from (2018) reprinted with permission from ref (8), copyright 2018 Springer Nature; ref (9), copyright 2018 Springer Nature; ref (13), copyright 2018 AAAS; with permission under a Creative Commons CC by 4.0 license from ref (15), copyright 2018 Springer Nature; and ref (17), copyright 2018 American Chemical Society. Panels from (2019) reprinted with permission from ref (22), copyright 2019 Springer Nature; ref (23), copyright 2019 Springer Nature; ref (20), copyright 2019 AAAS; ref (21), copyright 2019 AAAS; and ref (24), copyright 2019 Springer Nature. Panels from (2020) reprinted with permission from ref (25), copyright 2020 American Chemical Society; and ref (28), copyright 2020 Springer Nature. Panels from (2021) reprinted with permission from ref (29), copyright 2021 Springer Nature; ref (30), copyright 2021 Springer Nature; and ref (31), copyright 2021 John Wiley and Sons.