Effect of ion irradiation on the characteristics of magnetic tunnel junctions

¹ MESA Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands
² Francis Bitter Magnet Lab, MIT, 170 Albany Street, Cambridge, MA02139, USA
³ Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, Orissa, India
⁴ Nuclear Science Centre, Aruna Asaf Ali Marg, New Delhi 110 067, India

Corresponding author: T.Banerjee@ewi.utwente.nl

Received: 5 May 2005
Revised: 19 July 2005
Accepted: 20 July 2005
Published online: 26 October 2005

Abstract

The effect of disorder caused by MeV heavy ion irradiation on the tunnel magnetoresistance (TMR) of magnetic tunnel junctions is investigated. Two types of tunnel junctions, viz. Co/Al₂O₃/Ni₈₀Fe₂₀ and Co/Gd-doped Al₂O₃/Ni₈₀Fe₂₀ are studied. Upon 70 MeV Si ion irradiation at a fluence of  ions/cm², the undoped junctions show relatively small but irreversible change, while the Gd-doped junctions show a huge reduction, in TMR. In both cases junctions were completely destroyed by 200 MeV Ag ion irradiation at a fluence of ions/cm². The results are attributed to the modification of the barrier and the neighboring interfaces caused by the high energy density deposited by incident ions.