The influence of an ultra-high resistivity Ta underlayer on perpendicular magnetic anisotropy in Ta/Pt/Co/Pt heterostructures

Chan

J. Phys. D: Appl. Phys.

et al. 2023

Second-harmonic Hall voltage (SHV) measurement method has been widely used to characterize the strengths of spin-orbit torques (SOTs) in heavy metal/ferromagnet (HM/FM) thin films saturated in the single-domain regime. Here, we show that the magnetic anisotropy of a W/Pt/Co trilayer can be robustly tuned from in-plane to out-of-plane by varying W, Pt, or Co thicknesses. Moreover, in samples with easy-cone anisotropy, SHV measurements exhibit anomalous “humps” in the multidomain regime accessed by applying a nearly out-of-plane external magnetic field. These hump features can only be explained as a result of the formation of Néel-type domain walls, efficiently driven by nevertheless small SOTs in this double heavy metal heterostructure with canceling spin Hall angles.

Section: Tuning Magnetic Anisotropy In W/pt/cosupporting

confidence: 88%

Second-harmonic signature of chiral spin structures in W/Pt/Co heterostructures with tunable magnetic anisotropy

Chan

J. Phys. D: Appl. Phys.

et al. 2023

“…[8][9][10], L10 ordered tetragonal structures (CoPt,FePt) [11,12], HM/FM/HM (Pt/Co/Pt, Ir/Co/Pt etc.) trilayers [13][14][15] and rare earth-transition metal alloy films(TbFeCo, GdFeCo etc.) [16,17]can be used as a strong PMA structure.…”

Section: Introductionmentioning

confidence: 99%

“…), [8][9][10] L 10 ordered tetragonal structures (CoPt, FePt), 11,12) HM/FM/HM (Pt/Co/Pt, Ir/Co/Pt etc.) trilayers [13][14][15] and rare earth-transition metal alloy films (TbFeCo, GdFeCo etc) 16,17) can be used as a strong PMA structure. Among these materials, the magnetic multilayer films with PMA are of great interest because of their properties such as strong thermal stability, low critical current density, and strong out-of-plane magnetization for nanoscale spintronic applications (e.g.…”

Section: Introductionmentioning

confidence: 99%

Structural and morphological effect of Ti underlayer on Pt/Co/Pt magnetic ultra-thin film

Öcal¹,

Sakar²,

Öztoprak³

et al. 2021

Jpn. J. Appl. Phys.

Pt(xÅ)/Co(5Å)/Pt(10Å) trilayer films were deposited on naturally oxidized Si(111) substrate to investigate Ti underlayer effect on PMA. A small amount of Ti underlayer promoted the magnetic anisotropy to a perpendicular direction for x=8Å and 10Å. Both GI XRD and STM results showed that the Ti underlayer manipulated the growth of trilayer film. The Pt particles preferably grow the neighborhood of the Ti cluster, giving rise to a relatively smooth layer with a fiber texture fcc (111) structure. By contrast, the absence of Ti underlayer leads to clustered, relatively rough, and randomly oriented nano-crystalline growth. Differences in the growth mode, especially roughness, also appeared as intensity loss in XPS spectra due to shadowing effects. Our results indicate that a traceable amount of underlayer can change the magnetic anisotropy of the film by manipulating film growth.

“…This surface deposition energy is a common limiting factor when considering Pt growth on Si and is typically mitigated by the use of a refractory metal buffer layer, e.g. Ta 59 , to seed layer-by-layer growth. Here we see that the Nb(15) underlayer acts as an effective seed to Pt growth and so the combined stack provides an effective source of PMA, e.g., for mixed anisotropy spin valves, even at the low values required for superspintronic applications.…”

Section: Resultsmentioning

confidence: 99%

Electron beam evaporation of superconductor-ferromagnet heterostructures

Bromley

Wright

Jones

et al. 2022

Sci Rep

We report on the electronic and magnetic properties of superconductor-ferromagnet heterostructures fabricated by electron beam evaporation on to unheated thermally oxidised Si substrates. Polycrystalline Nb thin films (5 to 50 nm thick) were shown to possess reliably high superconducting critical temperatures ($$T_{c}$$ T c ), which correlate well with the residual resistivity ratio (RRR) of the film. These properties improved during ex-situ annealing, resulting in $${\Delta }T_{c}$$ Δ T c and $${\Delta }$$ Δ RRR increases of up 2.2 K ($$\sim$$ ∼ 40% of the pre-annealed $$T_{c}$$ T c ) and 0.8 ($$\sim$$ ∼ 60% of the pre-annealed RRR) respectively. Nb/Pt/Co/Pt heterostructures showed substantial perpendicular anisotropy in the ultrathin limit (≤ 2.5 nm), even in the extreme limit of Pt(0.8 nm)/Co(1 nm)/Pt(0.6 nm). These results point to the use of electron beam evaporation as route to line-of-sight deposited, low-thickness, high quality Nb-based superspintronic multilayers.