Evolution of ferromagnetism and electrical resistivity in Sb-doped Cr₄PtGa₁₇

We describe the doping effects on a metallic breathing pyrochlore compound, Cr₄PtGa₁₇. Upon doping with Sb, i.e., Cr₄Pt(Ga_1-xSb_x)₁₇, it was found that a selective doping on one of the seven Ga sites occurs. With increasing dopant level, the ferromagnetism in the parent compound is gradually suppressed, along with a decrease in fitted Curie-Weiss temperature (from 61 (1) K to −1.8 (1) K) and effective moment (from ∼2.26 μ_B/f.u. to ∼0.68 μ_B/f.u.). Low-temperature heat capacity measurements confirm the absence of magnetic ordering above 0.4 K for the three most doped samples. Meanwhile, electrical resistivity measurements display a metal-semiconductor transition with increasing Sb contents, which is attributed to an increase of Fermi energy based on the calculations of electronic band structure and density of states. Moreover, we have speculated that the ferromagnetism in Cr₄PtGa₁₇ is governed by itinerant electrons according to our observations. This study of Sb-doping effect on Cr₄PtGa₁₇ provides deeper understanding of magnetism of this system and possibilities for future modifications.