Crystal Growth and Physical Properties Evolution in Co‐Doped NiTe2 System

Abstract

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.