CoRuTiGe: A possible spin gapless semiconductor

We report experimental and theoretical investigations on the quaternary Heusler alloy CoRuTiGe, synthesized using the arc melting technique. Crystal structure analysis reveals a tetragonal structure at room temperature. Magnetization measurements as a function of temperature and magnetic field indicate a ferromagnetic nature with a saturation magnetization of $\ensuremath{\sim}0.681\phantom{\rule{0.28em}{0ex}}{\textmu{}}_{\mathrm{B}}/\mathrm{f}.\mathrm{u}.$ at 5 K. The temperature dependence of electrical resistivity shows a nearly linear decrease in the high-temperature range, indicating the spin gapless semiconductor (SGS) like behavior of the material. This SGS nature is further supported by the weak temperature-dependent carrier concentration and mobility. Hall effect analysis reveals that the anomalous Hall effect in CoRuTiGe arises from both intrinsic and extrinsic mechanisms. Additionally, a well-defined symmetric negative magnetoresistance is observed at low temperatures. These results offer insights that could aid in designing new spin gapless semiconductors with enhanced Curie temperatures for spintronic applications.