Dose dependence of ferromagnetism in Co-implanted ZnO

Abstract

We have studied the structural, magnetic, and electronic properties of Co-implanted ZnO͑0001͒ films grown on Al 2 O 3 ͑1120͒ substrates for different implantation doses and over a wide temperature range. Strong room temperature ferromagnetism is observed with magnetic parameters depending on the cobalt implantation dose. A detailed analysis of the structural and magnetic properties indicates that there are two magnetic phases in Co-implanted ZnO films. One is a ferromagnetic phase due to the formation of long range ferromagnetic ordering between implanted magnetic cobalt ions in the ZnO layer and the second one is a superparamagnetic phase, which occurs due to the formation of metallic cobalt clusters in the Al 2 O 3 substrate. Using x-ray resonant magnetic scattering, the element specific magnetization of cobalt, oxygen, and Zn was investigated. Magnetic dichroism was observed at the Co L 2,3 edges as well as at the O K edge. In addition, the anomalous Hall effect is also observed, supporting the intrinsic nature of ferromagnetism in Co-implanted ZnO films.

EPR study of Mn-implanted single crystal plates of TiO2 rutile

“…A number of experimental works report on the room temperature ferromagnetism observed in various oxides [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Despite of essential progress achieved in this field, there is still an open issue: whether intrinsic or extrinsic ferromagnetism is realized in these materials.…”

Deep level transient spectroscopic study of oxygen implanted melt grown ZnO single crystal

“…Other than introducing electrical doping into the ZnO material, 'magnetic doping' of ZnO could also be achieved by transition metal implantation. Room temperature ferromagnetism was reported in ZnO after ion implantation of Co, Ni, C and Fe [16][17][18][19][20][21], though the mechanism was not yet well understood. Hong et al [22] and Liu et al [23] have pointed out the influence of intrinsic defects on the magnetic property of transition metal doped ZnO.…”

Anisotropic magnetism and spin-dependent transport in Co nanoparticle embedded ZnO thin films

“…11 Thus, finding a good magnetoelectric response may pave the way to develop ZnO-based spintronics. Various methods have been used to fabricate ZnO-based MSs, including pulsed laser deposition (PLD), 12 sputtering, 13 ion implantation, [14][15][16] and electrochemical deposition. 17 In terms of applications ion implantation offers a convenient way to control dopant species and concentration.…”