Absence of ferromagnetism in V-implanted ZnO single crystals

TL;DR

This study investigates V-implanted ZnO single crystals and finds no evidence of ferromagnetism, despite successful V incorporation and structural integrity, challenging previous assumptions about magnetic doping in ZnO.

Contribution

It provides detailed analysis of V doping effects in ZnO, showing the absence of ferromagnetism and clarifying the role of V ions and structural stability.

Findings

No ferromagnetism observed down to 5 K

V ions successfully incorporated into ZnO lattice

Structural integrity maintained after implantation and annealing

Abstract

The structural and magnetic properties of V doped ZnO are presented. V ions were introduced into hydrothermal ZnO single crystals by ion implantation with fluences of 1.2*10^16 to 6*10^16 cm^-2. Post-implantation annealing was performed in high vacuum from 823 K to 1023 K. The ZnO host material still partly remains in a crystalline state after irradiation, and is partly recovered by annealing. The V ions show a thermal mobility as revealed by depth profile Auger electron spectroscopy. Synchrotron radiation x-ray diffraction revealed no secondary phase formation which indicates the substitution of V onto Zn site. However in all samples no pronounced ferromagnetism was observed down to 5 K by a superconducting quantum interference device magnetometer.