Effect of magnetic fullerene on magnetization reversal created at the Fe/C60 interface

Abstract

Probing the hybridized magnetic interface between organic semiconductor (OSC) and ferromagnetic (FM) layers has drawn significant attention in recent years because of their potential in spintronic applications. Recent studies demonstrate various aspects of organic spintronics such as magnetoresistance, induced interface moment etc. However, not much work has been performed to investigate the implications of such OSC/FM interfaces on the magnetization reversal and domain structure which are the utmost requirements for any applications. Here, we show that non-magnetic Fullerene can obtain non-negligible magnetic moment at the interface of Fe(15 nm)/C60(40 nm) bilayer. This leads to substantial effect on both the magnetic domain structure as well as the magnetization reversal when compared to a single layer of Fe(15 nm). This is corroborated by the polarized neutron reflectivity (PNR) data which indicates presence of hybridization at the interface by the reduction of magnetic moment in Fe. Afterwards, upto 1.9 nm of C60 near the interface exhibits magnetic moment. From the PNR measurements it was found that the magnetic C60 layer prefers to be aligned anti-parallel with the Fe layer at the remanant state. The later observation has been confirmed by domain imaging via magneto-optic Kerr microscopy.

Encoding Information on the Excited State of a Molecular Spin Chain

“…This hard unit comprises the bottom FM layer that is coupled across the spinterface to a molecular spin chain through exchange bias. [ 15,30,40–45 ] In the spin chain's ground state, they represent one magnetic unit (thick green arrow in Figure 1d). However, in the experimental conditions of the data of Figure 1c, the AF spin chain is in the electrically excited state (Figure 1b) and can act as a distinct steady‐state magnetic unit (yellow/green arrow and box of Figure 1d).…”

“…It has a very low magnetic anisotropy and is exchange‐coupled with energy J 12 MSC to the bottom FM layer (Figure 1d). Due to exchange bias, [ 15,30,40–45 ] the excited spin chain can switch its magnetic orientation at H ≈ 1.1 T (yellow/green arrow in Figure 1c). The bottom magnetic unit, comprising the FM layer and spinterface, eventually switches at higher H (bottom green arrow in Figure 1c).…”

“…To conclude, although a standalone chain of paramagnetic centers has no intrinsic magnetic orientation and its quantum excited states are short‐lived, [ 14 ] these shortcomings can be overcome by coupling [ 15,41,42 ] it to a ferromagnetic layer. Using a novel resist‐and solvent‐free nanotechnological process, we demonstrated how this enables information to be encoded at magnetic remanence in the magnetic orientation of the spin chain's excited quantum state in a solid‐state device.…”

Study of the magnetic interface and its effect in Fe/NiFe bilayers of alternating order

“…We plotted the experimental data of reectivity vs. perpendicular scattering vector Q Z ¼ 4p sin q/l where Q Z is the component of momentum transfer perpendicular to the sample surface, thus, giving sample's layer-by-layer information. 19,20 We always applied positive saturation eld and then reverse the eld to the measurement elds. The guiding eld was À1 mT.…”

“…We measured two non-spin ipped scattering cross sections namely R ++ and R ÀÀ . 19,20 In R ++ , the rst + sign is for the incident neutron with up-spin polarization and the second + sign is for the reected neutron with up-spin polarization. Similarly, we can explain R ÀÀ (down-down).…”