MFM and first order reversal curve (FORC) study of switching mechanism in Co25Pd75 films

Abstract

Recent research on CoPd alloys with perpendicular magnetic anisotropy (PMA) has suggested that they might be useful as the pinning layer in CoFeB/MgO-based perpendicular magnetic tunnel junctions (pMTJ's) for various spintronic applications such as spin-torque transfer random access memory (STT-RAM). We have previously studied the effect of seed layer and composition on the structure (by XRD, SEM, AFM and TEM) and performance (coercivity) of these CoPd films. These films do not switch coherently, so the coercivity is determined by the details of the switching mechanism, which was not studied in our previous paper. In the present paper, we show that information can be obtained about the switching mechanism from magnetic force microscopy (MFM) together with first order reversal curves (FORC), despite the fact that MFM can only be used at zero field. We find that these films switch by a mechanism of domain nucleation and dendritic growth into a labyrinthine structure, after which the unreversed domains gradually shrink to small dots and then disappear.

Multiple Nonvolatile Skyrmion States in Nanostructured Synthetic Antiferromagnetic Multilayers

“…To improve the feasibility of skyrmion-based spintronic devices, material systems that can host skyrmions at room temperature have been successively studied [31][32][33][34][35][36]. Ferromagnet-heavy-metal (FM-HM) multilayers are the mainstream skyrmion platform because of its compatibility with complementary metal oxide semiconductor manufacturing technology [37][38][39][40][41]. However, the stable existence of a skyrmion in FM-HM multilayers usually needs a large interfacial Dzyaloshinskii-Moriya interaction (DMI) and the assistance of an external field [42].…”

Interwire and Intrawire Magnetostatic Interactions in Fe‐Au Barcode Nanowires with Alternating Ferromagnetically Strong and Weak Segments

“…The elemental composition of each segment was studied by dispersive X-ray analysis (energy dispersive X-ray spectroscopy, EDX), which showed that in both Au and Fe segments, a ferromagnetic alloy was formed with a different ratio of elements depending on the deposition conditions. A first-order reversal curve (FORC) diagram analysis [17][18][19][20][21][22] showed a nontrivial distribution of interaction fields in the samples, heavily dependent on the geometrical parameters of magnetic segments. We implemented a micromagnetic model using the MuMax 3 software [23] to explain such behavior and determine the magnetization configuration in the Fe-Au BNWs.…”

Role of film thickness and disorder in tuning perpendicular magnetic anisotropy in GdTb-FeCo alloy films

“…There are several amorphous systems like CoFeB [12], FeTaC [13], and CoSiB/Pt [14] multi-layers (MLs) etc and structured systems like L1 0 ordered Co/Pt- [15,16], and Co/Pd-MLs showing PMA [17][18][19]. These systems are mostly investigated by inserting an under-layer or repeating several MLs to achieve the enhancement in the magnetic and microscopic properties.…”