Room-temperature ferromagnetism in boron-doped oxides: a combined first-principle and experimental study

ABSTRACT

The ferromagnetic properties of boron-doped oxides, namely ZnO, MgO, CdO and TiO₂ have been studied using first-principle calculations based on density functional theory. A boron atom, when doped at an anion site, generates a magnetic moment per dopant atom ranging from ∼1 µ_B in TiO₂ to ∼3 µ_B in ZnO. The source of magnetism in the boron-doped oxides is the 2p-orbital electrons of the dopant atom plus a small contribution coming from the oxygen atoms surrounding the dopant. A spin–spin interaction study reveals that the doping of B at O sites favours ferromagnetic spin coupling in ZnO, MgO, CdO and TiO₂. Boron-doped samples have been prepared by ion-beam irradiation with a 10 keV B⁺ beam implanting on sample pallets. Magnetic measurements have been carried out for B⁺-ion-implanted oxide samples using a SQUID magnetometer. A stable room-temperature ferromagnetic ordering is observed in boron-ion-irradiated ZnO, MgO, CdO and TiO₂ samples.

KEYWORDS:

• Magnetic semiconductors
• density functional theory
• ion-beam implantation
• boron doping
• oxides

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

PC thanks the Department of Science and Technology, Government of India (No: DST/INSPIRE Fellowship/2013/958) [IF130752] for financial support under the DST INSPIRE scheme. AT would like to thank SERB (File no. ECR/2018/000212) for financial assistance.