Atomic Assembly of Giant Magnetoresistive Multilayers

Abstract

The emergence of metal multilayers that exhibit giant magnetoresistance (GMR) has led to new magnetic field sensors, and approaches for nonvolatile random access memories. Controlling the atomic scale structure across the many interfaces within these multilayers is central to improve the performance of these devices. However, the ability to manipulate atomic arrangements at this scale requires an understanding of the mechanisms that control heterometal film growth during vapor deposition. It is important to develop methods that enable prediction of the effects of deposition conditions upon this structure. Atomistic simulation approaches have been combined with deposition reactor models to achieve this. We have applied these approaches to analyze the atomic scale structure of sputter deposited CoFe/Cu/CoFe giant magnetoresistive multilayers similar to those used for magnetic field sensing. Significant intermixing is revealed at the CoFe-on-Cu interface, but not at the Cu-on-CoFe interface. Recent experiments verified these predictions. The insights provide a basis for the development of processes that inhibit thermally activated atomic diffusion while allowing the controlled use of the metal atom impact energy and inert gas ions to manipulate the structure of interfaces.

Molecular dynamics simulations of argon cluster impacts on a nickel film surface

“…The interactions between metal thin film atoms were modeled using the embedded-atom method (EAM), which was originally developed by Daw and Baskes [12]. The analytical EAM function of Ni atoms determined by Wadley et al [13] was utilized to calculate the interactions between the metal atoms. The Lennard-Jones potential was applied for Ni-Ar and Ar-Ar interaction [14].…”

Atomic Investigation of Al/Ni(001) by Molecular Dynamics Simulation

“…5) The thin-film quality is generally known to be influenced by the substrate temperature and the deposition rate of adatoms. [6][7][8] Therefore, an understanding of the proper quantitative relation between the morphologies of growing thin films and different sputtering process parameters is an essential issue for film quality control in device manufacturing.…”