Direct Visualization of Canted Magnetization and Topological Charges in Self-Intercalated van der Waals Magnet Cr1+δTe2 with Hidden Structural Phases.

Intercalated van der Waals (vdW) magnets have attracted growing interest owing to their rich and highly tunable magnetic properties and their promise for ultracompact spintronic applications. A remarkable example is self-intercalated chromium tellurides (Cr1+δTe2), in which spatially ordered chromium atoms occupy the vdW gaps, yielding a variety of known compounds (e.g., Cr1.25Te2, Cr1.33Te2, and Cr1.5Te2) that host distinct and intriguing magnetic states. In this work, we uncover the existence of hidden, ordered self-intercalated phases that form spontaneously along with a twisted Cr1.5Te2 phase in chromium telluride nanoflakes grown by chemical vapor deposition. Using wide-field and scanning diamond nitrogen-vacancy center (NV) magnetometry, we unveil intricate magnetic structures in the chromium telluride flakes at the nanoscale and above room temperature. In a small nanoflake, the magnetization prefers an in-plane orientation in its interior with strong anisotropy but is tilted out of plane at the edges. In a large nanoflake, we observe complex magnetic profiles indicating the possible formation of nontrivial localized topological structures. Our work demonstrates the versatility of self-intercalation beyond known phases and the rich magnetic properties in a model vdW magnet, highlighting its great potential for room-temperature spintronic applications.