Near and above room temperature ferromagnetism in new self-intercalated chromium tellurides

Chromium tellurides (Cr_1+δTe₂) are one of the most versatile families of self-intercalated van der Waals (vdW) magnetic materials that offer great potential for ultracompact spintronics. The magnetic properties of the system are strongly dependent on the number and order of the intercalated chromium atoms in the vdW gap. In this work, we report on the realization of various new self-intercalated structural phases that host ferromagnetism near or well above room temperature. The new phases are realized in nanoplates grown by chemical vapor deposition, and their intercalated structures are carefully characterized by transmission electron microscopy. We will present a systematic study of their magnetic properties using a series of experimental tools, including bulk magnetization measurements, temperature- and field dependent magneto-optic Kerr effect, and direct imaging of stray field using nitrogen-vacancy (NV) magnetometry. Particularly, in the NV measurements, magnetic stray field maps of individual nanoplates show an unusual four-leaf structure, suggesting intricate local magnetic phases or domain structures that the system possesses.