Semiconductor-insulator transition in a YbB₆ nanowire with boron vacancy

In this paper, we report the study of transport and magnetic properties of ytterbium hexaboride (YbB₆) nanowires grown by a low trigger-temperature (200–240 °C) solid state method. The temperature dependence of resistivity shows that the YbB₆ nanowire undergoes a semiconductor-insulator transition (SIT) below 20 K with an activation energy ΔE of 1 meV. The value of ρ at 2 K reaches 49 times the value of ρ at 300 K (ρ_{2 K}/ρ_{300 K} = 49). The observed non-saturating magnetoresistance (MR) has a linear relationship with B². The anomalous electronic transport in the YbB₆ nanowire can be explained by the mixed valence of Yb ions due to the boron deficiency supporting by the X-ray photoelectron spectroscopy (XPS) and paramagnetic magnetization.