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The relatively low Curie temperature (Tc) in recently discovered two-dimensional ferromagnetic (FM) materials has limited their potential applications in designing next generation electronics. Searching for new low-dimensional layered materials with room-temperature Tc is highly needed. Here, we report the study of layered FM materials Cr5+xTe8 (x = −0.10, 0.11, 0.56, 1) in which Tc can be well manipulated by the Cr content. Single crystalline Cr5+xTe8 samples have been synthesized and characterized by energy dispersive x-ray spectroscopy, x-ray diffraction, and magnetization measurements. We have found that Tc increases monotonically with Cr content and reaches 313 K at x = 1. While the FM coupling is enhanced with an increase in the Cr content, the antiferromagnetic (AFM) phase at low temperatures is suppressed. Due to the competition of FM and AFM phases, a wasp-waist loop is observed on isothermal magnetization curves. A magnetic flip occurs by changing the temperature and magnetic field to overcome the flipping energy barrier. Our results indicate that the Cr5+xTe8 system serves as a promising platform to tune the 2D ferromagnetism in layered materials.

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Transition metal tellurides have been widely studied for their diverse crystal structures and exotic physical properties such as large magnetoresistance, charge density waves, superconductivity, ferromagnetic and topological properties. NiTe2 has recently been found to be a Dirac semimetal, allowing it to achieve exotic properties by pressure and doping. A series of Ni1−xCoxTe2−δ single crystals are synthesized by the standard solid‐state reaction method. The energy‐dispersive X‐ray spectroscopy and X‐ray diffraction tests confirm Co is successfully doped into the crystal structure. The electrical transport measurements show typical metallic behaviors for all the samples. Magnetization measurements reveal that, in the doping range of x = 0.12–0.62, the samples exhibit a coexistence of antiferromagnetic and paramagnetic phases above the characteristic temperature Tt. By using the combined Curie–Weiss and spin‐wave model, the antiferromagnetic to ferromagnetic transition is found to occur as the temperature drops below Tt. The magnetic transition is attributed to the Te vacancies, which can be explained using the bound magnetic polaritons model. A magnetic phase diagram for Ni1−xCoxTe2−δ system is constructed.