*3.2.1 SEM image of Mn-doped ZnO nanowires*

The ZnO nanowires were synthesized by a thermal evaporation method with 1 atom % Mn doping [44]. **Figure 4a** is a SEM image of Mn/ZnO nanowires of several micrometer lengths and 70 nm diameters. The reported work given TC to be 437 K

#### **Figure 4.**

*(a) Scanning electron microscopy (SEM) pattern for ZnO/Mn nanowires. (b) HRTEM for Zn0.92Fe0.05La0.03O nanoparticles. (c) TEM pattern for Zn0.91Ni0.05Ce0.04O nanoparticles. (d) AFM pattern for pure ZnO (adapted from [21, 27, 44, 45]).*

from SQUID measurements. The difference of ΔMR is up to 2.5% as the gate voltage changes from 40 to +40 V at T = 1.9 K, which suggests the electric field control of ferromagnetism for realizing spin logic devices.
