  Magnetic tunnel junction-based molecular spintronics devices (MTJMSDs) are
designed by covalently connecting the paramagnetic molecules across two
ferromagnets (FM) electrodes of a magnetic tunnel junction (MTJ). MTJMSD
provides opportunities to connect FM electrodes of a vast range of anisotropy
properties to a variety of molecules of length scale. Our prior studies showed
that the paramagnetic molecules can produce strong antiferromagnetic coupling
with FM electrodes. The device properties of MTJMSD depend upon various factors
such as anisotropy, spin fluctuation, thermal energy, etc. In this paper, we
report a theoretical Monte Carlo Simulation (MCS) study to explain the impact
of anisotropy on the MTJMSD equilibrium properties. We studied the energy
variation of the MTJMSD system with time as a function of FM electrode
anisotropy. Experimentally designed FM electrodes of MTJMSD contain
multi-layers of different ferromagnetic materials. These materials possess
in-plane and out-of-plane magnetic anisotropy characteristics. To understand
the competing effect of in-plane and out-of-plane anisotropy, we have
computationally applied anisotropies on the left FM electrode. For the MCS
study, the orientation of the device was kept along YZ plane. As a result, the
applied anisotropy along the X-direction (\mathbit{A}_{\mathbit{Lx}}) and
Y-direction (\mathbit{A}_{\mathbit{Ly}}) represent out-of-plane and in-plane
anisotropy, respectively. We found that increasing anisotropy strength starts
exhibiting diverse domain structures within an FM electrode. Increasing the
magnitude of anisotropy was found to create stripe-shaped domains with opposite
spins. These domains represent the different magnetic phases. However, the
application of equal magnitude of in-plane and out-of-plane cancels the strip
domain formation and lowers the magnetic moment of overall MTJMSD.
