Effect of Post-Annealing on Magnetotransport and Magnetic Properties of TaCo2Te2 Single Crystals

The extreme magnetoresistance (XMR) of some compounds, challenging our understanding of magnetoresistance, is an interesting topic in condensed-matter and materials physics and future device applications. Here, we reported magnetotransport and magnetic properties of the as-grown and post-annealed TaCo2Te2 single crystals. The resistivity evolution with temperature in the two TaCo2Te2 single crystals shows a metallic behavior. Below 50 K, the XMR effect for the two crystals is found, and MR values at 3 K under 9 T are about 3.72 × 103% for the as-grown TaCo2Te2 and 5.71 × 102% for the annealed samples, larger than that of the previous report. The studies on the Hall effect of the two TaCo2Te2 single crystals indicate the multiband feature with high carrier mobilities from a two-band model. Electron and hole concentrations and mobilities of as-grown samples are comparable, while for the annealed sample, the hole concentration and mobility are larger than the electron concentration and mobility. The carrier mobilities for the two TaCo2Te2 single crystals have the same order of magnitude, ∼103 cm2 V-1 s-1. The XMR effect may be from high carrier mobilities. Magnetization of the as-grown TaCo2Te2 decreases with increasing temperature, and a weaker magnetic transition at ∼150 K is observed. The annealed TaCo2Te2 shows no magnetic transition and just a paramagnetic behavior with rising temperature. These results indicate that defects/deficiencies may play an important role in magnetotransport and magnetic properties of the two TaCo2Te2 single crystals. These results are helpful in deeply understanding the XMR mechanism and magnetic properties in TaCo2Te2 and offer a way to study the magnetic properties of the XMR Co-Te system.