[Co/Pd]–NiFe exchange springs with tunable magnetization tilt angle

Abstract

We investigate exchange coupled [Co/Pd]5–NiFe thin films. Due to competition between the in-plane shape anisotropy of the NiFe and strong perpendicular magnetic anisotropy of the [Co/Pd]5 multilayer, unique magnetic configurations are achievable. In particular, we explore the out-of-plane magnetization tilt angle of the NiFe layer. Experimental results, based on conventional magnetometry, ferromagnetic resonance, and magnetic force microscopy, agree well with one-dimensional micromagnetic simulations. We find that the tilt angle is highly tunable (0°–60°) over a small range of NiFe thicknesses (4.8–8 nm). Potential applications for high power, zero-field operation spin torque oscillators are discussed.

Magnetic structure and anisotropy of[Co/Pd]5/NiFemultilayers

“…The plane-normal loops in Fig.1(d, e) reveal a significant remanence and the samples with NiFe thickness of 0 nm to 5 nm could be saturated below 100 kA/m. The remanence shows a clear decreasing trend for samples with NiFe layer of 5 nm to 15 nm thickness, which is in an agreement with our previous studies 16 . Fig.…”

“…In this work, we investigate the role of the soft layer on the magnetic anisotropy, domain structure and damping in exchange-coupled [Co/Pd] 5 /NiFe films. The results are extended to a wider range of NiFe layer thicknesses, from 3 nm to 80 nm, compared with previous studies 16,17,19 . Also we characterize damping and anisotropy by ferromagnetic resonance measurements, and domain structure by magnetic imaging and simulation.…”

“…1(a)). The thin amorphous Ta seed layer allows for greater mobility of the deposited atoms and an improved fcc-(111) orientation of the Pd layer deposited upon it, thus improving the perpendicular anisotropy of the [Co/Pd] multilayers 16,27 . Samples were characterized by vibrating sample magnetometry (VSM), magnetic force microscopy (MFM) and ferromagnetic resonance spectroscopy (FMR).…”

“…In prior modeling 16 , the NiFe magnetization tilted towards the film plane with increasing distance from the interface. The tilt reached 60…”

Interlayer interaction in multilayer [Co/Pt]n/Pt/Co structures

“…Over the last few years certain attention has been focused on the properties of exchange coupled systems with distinct anisotropy directions [9][10][11][12][13][14][15][16][17][18][19][20] . In particular, CoPt/F structures that consist of CoPt multilayer film with "easy axis" anisotropy and ferromagnetic layer (F) with "easy plane" anisotropy have been proposed to control hysteresis loop shift (exchange bias) of magnetic system [12][13][14] .…”