Effect of N⁺ irradiation on the microstructural and magnetic properties of Co/Pd multilayers

¹ ISM – CNR, Area della Ricerca di Roma, P.B. 10, 00016 Monterotondo Stazione, Rome, Italy
² Instituto de Microelectrónica de Madrid, IMM (CNM-CSIC) C/Isaac Newton, 8 (PTM) 28760 - Tres Cantos, Madrid, Spain
³ Institut de Microelectrònica Barcelona, Campus Universitat Autònoma Barcelona, 08193, Bellaterra, Spain
⁴ UNAXIS Data Storage, 9496 Balzers, Liechtenstein

Corresponding author: albertomaria.testa@ism.cnr.it

Received: 14 November 2006
Accepted: 23 March 2007
Published online: 30 May 2007

Abstract

Microstructural and magnetic properties of ¹⁴N⁺ irradiated Co/Pd multilayers, deposited on ultra-flat large (2.5 in) glass substrates by a special hard disk industrial manufacturing system, are discussed. Upon irradiation with ¹⁴N⁺ ions at different energies (20–30 keV) and doses (10¹⁴–10¹⁵ ions/cm²), both the coercive and nucleation fields were found to change with respect to as deposited multilayer. Results indicate that the irradiation process leads to a lowering of the magnetic anisotropy due to the induced disorder and degradation of the interface quality: for an energy of 30 keV, at an irradiation level of 10¹⁵ ions/cm², H_c reduces from H_c ≈ 5.4 kOe for the as deposited multilayer down to 300 Oe, being the easy axis still perpendicular to the multilayer plane; at the highest dose (10¹⁶ ions/cm²), the coercivity vanishes and the perpendicular anisotropy is suppressed.