Enhanced anisotropy and study of magnetization reversal in Co/C60 bilayer thin film

Abstract

The interface between the organic semiconductor (OSC)/ferromagnetic (FM) material can exhibit ferromagnetism due to their orbital hybridization. Charge/spin transfer may occur from the FM to OSC layer leading to the formation of “spinterface,” i.e., the interface exhibiting a finite magnetic moment. In this work, the magnetic properties of the Co/C60 bilayer thin film have been studied to probe the interface between the Co and C60 layer. Polarized neutron reflectivity (PNR) measurement indicates that the thickness and moment of the spinterface are ∼2 ± 0.18 nm and 0.8 ± 0.2 μB/cage, respectively. The comparison of the magnetization reversal between the Co/C60 bilayer and the parent single layer Co thin film reveals that spinterface modifies the domain microstructure. Further, the anisotropy of the bilayer system shows a significant enhancement (∼two times) in comparison to its single layer counterpart which is probably due to an additional interfacial anisotropy arising from the orbital hybridization at the Co/C60 interface.

Effect of Fullerene on domain size and relaxation in a perpendicularly magnetized Pt/Co/C60/Pt system

“…This in-dicates the hardening the pinning of out-of-plane magnetization due to strong adsorption of C 60 on Co-substrate. In our previous study on Co-C 60 in-plane system, we have also seen that introducing a C 60 layer anisotropy of system has been increased [23].…”

“…Similarly, for C 60 deposited on a polycrystalline Fe films also exhibited spinterface and domain size was reduced [22]. Further in another study we have shown that the spinterface in a Co/C 60 system has similar effect, however the anisotropy increased due to the spinterface [23]. Although there have been a few works on in-plane magnetized films however the study of such spinterface on domains in a perpendicularly magnetized films are scarce.…”

“…There is a high chance of formation of a spinterface due to spin polarized charge transfer and orbital hybridization at the OSC-FM interface [16,17]. Because of this the density of states of the OSC get modified and the OSC can exhibit ferromagnetism [10,[18][19][20][21][22][23][24][25]. The effect of spinterface has been shown in many in-plane magnetized systems.…”

Evidence of a C60 /Co interface reconstruction and its influence on magnetic properties

“…Surprisingly, not only the spin polarization but also the magnetic anisotropy has been found deeply modified at the molecule/ferromagnet interface. For example, the C p z -Co d z 2 hybridization has been demonstrated to be at the origin of an enhanced perpendicular anisotropy at the C 60 /Co(0001) interface [7,8], which induces a magnetic hardening in either out-of-plane [9] or in-plane magnetized samples [10]. The link between magnetic properties and the fine details of the interface structure has not been studied extensively up to now for such samples even if few experimental evidences have been reported, either on the magnetic [11] or the transport properties [12].…”

Spin pumping and inverse spin Hall effect in CoFeB/C$_{60}$ bilayers

“…C 60 can exhibit ferromagnetism at the interface (known as spinterface) when it is deposited on any ferromagnet 21,22 . Presence of C 60 can modify the magnetic property of the ferromagnetic materials as well as nonmagnetic metal [23][24][25][26][27][28] . However, the low value of SOC in OSC limits them for efficient spin to charge conversion.…”