“…CMR effect has been observed in chromium-based chalcogenide materials with spinel structures, ACr 2 Q 4 (A = transition metal, Q = S, Se) [3,7], e.g., Cu-and Cr-based systems, CuCr 2 S 4 , CuCr 2 Se 4 and CuCr 2 Te 4 , which are metallic and ferromagnetic with Curie temperatures (T C ) of ~380, ~420, and ~300 K, respectively [8][9][10]. The magnetism in these compounds can be attributed to the double exchange between Cr 3+ and Cr 4+ [8].…”