Widely Tunable Berry Curvature in the Magnetic Semimetal Cr_1+δTe₂

Abstract

Magnetic semimetals have increasingly emerged as lucrative platforms hosting spin‐based topological phenomena in real and momentum spaces. Cr1+δTe2 is a self‐intercalated magnetic transition metal dichalcogenide (TMD), which exhibits topological magnetism and tunable electron filling. While recent studies have explored real‐space Berry curvature effects, similar considerations of momentum‐space Berry curvature are lacking. Here, the electronic structure and transport properties of epitaxial Cr1+δTe2 thin films are systematically investigated over a range of doping, δ (0.33 – 0.71). Spectroscopic experiments reveal the presence of a characteristic semi‐metallic band region, which shows a rigid like energy shift with δ. Transport experiments show that the intrinsic component of the anomalous Hall effect (AHE) is sizable and undergoes a sign flip across δ. Finally, density functional theory calculations establish a link between the doping evolution of the band structure and AHE: the AHE sign flip is shown to emerge from the sign change of the Berry curvature, as the semi‐metallic band region crosses the Fermi energy. These findings underscore the increasing relevance of momentum‐space Berry curvature in magnetic TMDs and provide a unique platform for intertwining topological physics in real and momentum spaces.

Above-Room-Temperature Ferromagnetism in Copper-Doped Two-Dimensional Chromium-Based Nanosheets

“…Besides, the extracted H c gradually vanishes, approaching zero at a transition temperature T S ∼ 120 K, where the rectangular hysteresis loop basically disappears, and then keeps a relatively small value until the T c of ∼315 K to once more zero. Because we did not collect more detailed temperature points at 90−120 K, it dropped sharply at 120 K. Notably, as the temperature increased, the sign of R AHE changes at T S ∼ 120 K, indicating a transition temperature T S at ∼120 K. Moreover, such sign reversal behavior of the AHE has also been observed in various Cr 1+δ Te 2 compounds 58,60,63 and Pd/Co multilayers. 59 Likewise, with the rising temperature, remnant Hall resistance R r xy changes from negative to zero when T ≈ T S , where the hysteresis loop disappears.…”

Hole‐Mediated RKKY Interaction in 2D Ferromagnetic CrTe2 Ultra‐Thin Films

“…The positive slope of R xy observed at high magnetic fields suggests that the majority of carriers in the film are holes. [30,31] The relationship between R xy and the magnetic field can be described by the empirical equation R xy = R 0 H + R a M, where the first term represents the ordinary Hall effect, and the second term represents the Anomalous Hall effect (AHE). The empirical formula is used to study the formation mechanism of the Anomalous Hall resistance ( R AHE = R xy − R 0 H = R a M).…”

Amorphous Ferromagnetic Metal in van der Waals Materials

“…Hence, the decrease in the Cr─Te bond length and the change to a local structure close to the Cr─Te alloys potentially give rise to a ferromagnetic metallic state with a high T C . Moreover, the sign of anomalous Hall resistivity for Cr─Te crystalline alloys changes sensitively depending on their composition [ 32 ] and strain. [ 33 ] This could explain the two anomalous Hall components observed in the heavily irradiated CrGeTe 3 .…”