Stable canted magnetization in Co thin films on highly oriented pyrolytic graphite induced by template defects

Abstract

Co thin films were grown on planar highly oriented pyrolytic graphite (p-HOPG) and Ar þ sputtered HOPG (s-HOPG) for comparison. Measurement of Auger ratio Co/C suggested the more uniform nucleation for Co on s-HOPG. Co/p-HOPG exhibited only in-plane magnetization, whereas Co/s-HOPG revealed the coexistence of in-plane and perpendicular MOKE hysteresis loops, indicating stable canted magnetization. The canted magnetization of Co/s-HOPG, which persisted at least up to 50 ML, could be attributed to volume-contributed perpendicular anisotropy. These observations will be valuable for future applications in the combination of metallic magnetic materials and carbon-based templates. V

Extrinsic Spin–Orbit Coupling-Induced Large Modulation of Gilbert Damping Coefficient in CoFeB Thin Film on the Graphene Stack with Different Defect Density

“…A similar value of intrinsic SOC for few-layer graphene and graphite is deduced, which is an order of magnitude higher than that of single-layer graphene . In this situation, their extrinsic SOC strength can play a crucial role in controlling the magnetization dynamics at graphene stack/FM system. ,− The spin injection and transport has been achieved in both graphene and graphite. − ,,− The experimental spin-relaxation length (∼2 μm) in single-layer graphene at room temperature , is still one order of magnitude below theoretical predictions. , Because the spin relaxation is believed to be caused mostly by extrinsic scatters in the substrate and on the graphene surface, , reduction of the effect of these scatters should lead to an increase in the spin-relaxation length . In a stack of graphene layers, the scattering potentials are screened by the outer layers with a screening length of about five layers, depending on the stacking order.…”

Magnetic patterning through graphene protection against oxidation and interlayer diffusion

“…CoPd alloy films were deposited on SiO 2 /Si(001) substrates through electron-beam (e-beam)-heated coevaporation in an ultrahigh vacuum (UHV) with a base pressure of 5×10 −9 mbar [20][21][22][23][24][25]. The evaporation rates were controlled through the adjustment of the emission currents applied to the sources, and a high accelerating voltage of 1 kV was applied.…”

“…This can be interpreted according to the different growth modes of Fe on the two surfaces. Fe deposition on bare CoPd forms a continuous two-dimensional (2D) film, whereas Fe growth on Gr/CoPd is more three-dimensional (3D) with assemblies of nanoparticles [24,25]. Therefore, the Curie temperature and magnetization are relatively low because of the finite-size effect.…”

Oxygen surfactant-assisted growth and dewetting of Co films on O-3 × 3/W(111)

“…The consistence between the Co 776eV /W 170eV AES signal ratio of RT and LT-grown Co films also supports the 2-D growth mode of 300-200 K grown Co films on O-3 Â 3/W(111). 28,29 For comparison, our recent study of Ni/O-3 Â 3/W(111) shows the Ni 776eV /W 170eV Auger ratio increased more and more slowly with increasing Ni deposition (curvature < 0). 30 This suggests, in contrast to the 2D growth of Co, Ni preferred the 3-dimensional (3D) growth behavior on O-3 Â 3/W(111), which might be due to the large mismatch between Ni and W. Fig.…”