Strain-induced magnetoresistance and magnetic anisotropy properties of Co/Cu multilayers

Abstract

[Co (tCo) nm/Cu 1.5 nm]50 multilayers were grown onto 15-nm Cu/polyimide buffer layers. The relationship between stress, σ, and strain, ɛ, for the [Co 1.0 nm/Cu 1.5 nm]50 multilayers has been presented. The effects of induced strain on the magnetoresistance (MR) and magnetic anisotropy have been examined. The [Co 1.0 nm/Cu 1.5 nm]50 multilayer exhibited a maximum MR ratio of 3.4% at a Co layer thickness of 1.0 nm, β of 0.1, and a strain of 1.5%. The multilayers exhibited a remarkable magnetic anisotropy with the easy axis of magnetization always lying in a plane perpendicular to the direction of the induced strain.

Ferromagnetic Multilayers: Magnetoresistance, Magnetic Anisotropy, and Beyond

“…Our paper that was published earlier, describes about this technique in detail [40]. In this review, we show several examples of real and potential applications of materials with perpendicular magnetic anisotropy, PMA: ultra-sensitive sensors, ultra-low power STT-based magnetic random access memory, magnetic switches and logic structures, and detection and therapy.…”

“…In Figure 1c-ii [40], the white big arrows outside the sample show the direction of mechanical force, and the correspondingly induced MA is shown by dark black arrows inside the sample. As shown in this Figure, the easy axis of M is along the perpendicular direction to the direction of .…”

“…As shown in this Figure, the easy axis of M is along the perpendicular direction to the direction of . Our recent experimental observations have shown that obliquely deposited as well as externally -induced metals and multilayered films of FM exhibit strong in-plane or perpendicular-to-plane uniaxial MA, depending on FM layer thickness [7,40].…”

“…The inset shows M-H curves when the is changed in the range of 1.5%. Adapted from [40], Copyright AIP Publishing LLC, 2012.…”

“…The anisotropy constant for pure Co, K u1 = 5 × 10 6 erg/cc (20 μ eV/atom) [39]. (b) structure showing magnetic alignment from antiparallel to parallel due to H field; (c) Schematic of inducing strain, in the sample: In (c-i), position of the multilayer films, the direction of the applied mechanical force, and the position of the electromagnets; and (c-ii), directions of the applied mechanical and magnetic forces, and the direction of correspondingly the induced magnetic easy axis, Adapted from [40], Copyright AIP Publishing LLC, 2012; (d) The peak of the GMR corresponding to H c ; (e) FM Multilayers for = 0 and = 0 case; (f) A relationship between the magnetic anisotropy constant, K u , and the induced . The inset shows M-H curves when the is changed in the range of 1.5%.…”