Layer-Number-Independent Two-Dimensional Ferromagnetism in Cr 3 Te 4 .

In a conventional magnetic material, a long-range magnetic order develops in three dimensions, and reducing a layer number weakens its magnetism. Here we demonstrate anomalous layer-number-independent ferromagnetism down to the two-dimensional (2D) limit in a metastable phase of Cr 3 Te 4 . We fabricated Cr 3 Te 4 thin films by molecular-beam epitaxy and found that Cr 3 Te 4 could host two distinct ferromagnetic phases characterized with different Curie temperatures ( T C ). One is the bulk-like "high- T C phase" showing room-temperature ferromagnetism, which is consistent with previous studies. The other is the metastable "low- T C phase" with T C ≈ 160 K, which exhibits a layer-number-independent T C down to the 2D limit in marked contrast with the conventional high- T C phase, demonstrating a purely 2D nature of its ferromagnetism. Such significant differences between two distinct phases could be attributed to a small variation in the doping level, making this material attractive for future ultracompact spintronics applications with potential gate-tunable room-temperature 2D ferromagnetism.