Gate-controlled transport properties in dilute magnetic semiconductor (Zn, Mn)O thin films

Ionic liquid (IL) gating of functional oxides has drawn significant attention, since it can provide reversible changes in carrier concentration (10¹⁴ cm^-2) at the interface, permitting the manipulation of electrical and magnetic properties of oxide films with low voltages. In this paper, we demonstrated the electric-field manipulation of transport properties in the dilute magnetic semiconductor of Zn_0.98Mn_0.02O (MZO), using an electric-double-layer transistor geometry through the IL electrolyte gating. The MZO layer exhibited reversible control of resistance up to 33% at 230 K. Moreover, magnetoresistance (MR) measurements revealed the influence of applied gate voltage (V_g) on the magnetotransport behavior, which exhibited a positive MR in the low-field region and a negative MR in high magnetic field (up to 9 T). An increase in low-field positive MR (<1 T) upon switching V_g from-2 to 2 V implied an enhanced ferromagnetic state of MZO due to an increased electron carrier concentration. The results demonstrated that a controllable carrier concentration by electric-field effect played an important role in the manipulation of magnetism in MZO.