title: Electric-field control of ferromagnetism in Mn-doped ZnO nanowires.
abstract: In this Letter, the electric-field control of ferromagnetism was demonstrated in a back-gated Mn-doped ZnO (Mn-ZnO) nanowire (NW) field-effect transistor (FET). The ZnO NWs were synthesized by a thermal evaporation method, and the Mn doping of 1 atom % was subsequently carried out in a MBE system using a gas-phase surface diffusion process. Detailed structural analysis confirmed the single crystallinity of Mn-ZnO NWs and excluded the presence of any precipitates or secondary phases. For the transistor, the field-effect mobility and n-type carrier concentration were estimated to be 0.65 cm(2)/V·s and 6.82 × 10(18) cm(-3), respectively. The magnetic hysteresis curves measured under different temperatures (T = 10-350 K) clearly demonstrate the presence of ferromagnetism above room temperature. It suggests that the effect of quantum confinements in NWs improves Tc, and meanwhile minimizes crystalline defects. The magnetoresistace (MR) of a single Mn-ZnO NW was observed up to 50 K. Most importantly, the gate modulation of the MR ratio was up to 2.5 % at 1.9 K, which implies the electric-field control of ferromagnetism in a single Mn-ZnO NW.
authors.affiliation: Device Research Laboratory, Department of Electrical Engineering, University of California , Los Angeles, California 90095, United States.
authors.forename: Li-Te
authors.initials: LT
authors.lastname: Chang
authors.forename: Chiu-Yen
authors.initials: CY
authors.lastname: Wang
authors.forename: Jianshi
authors.initials: J
authors.lastname: Tang
authors.forename: Tianxiao
authors.initials: T
authors.lastname: Nie
authors.forename: Wanjun
authors.initials: W
authors.lastname: Jiang
authors.forename: Chia-Pu
authors.initials: CP
authors.lastname: Chu
authors.forename: Shamsul
authors.initials: S
authors.lastname: Arafin
authors.forename: Liang
authors.initials: L
authors.lastname: He
authors.forename: Manekkathodi
authors.initials: M
authors.lastname: Afsal
authors.forename: Lih-Juann
authors.initials: LJ
authors.lastname: Chen
authors.forename: Kang L
authors.initials: KL
authors.lastname: Wang