Effect of Adatoms on Magnetic Anisotropy Energy
and Curie Temperature of SmCo5 Surface Slabs
Using First Principles Approach
S Selva Chandrasekaran1, P Murugan1*, P Saravanan2 and S V Kamat2
1
CSIR-Central Electrochemical Research Institute, Kraikkudi-630 006, India
2
Defence Metallurgical Research Laboratory, Hyderabad-500 058, India
*
e-mail: murugan@cecri.res.in
Abstract
Deposition of different adatoms such as Co, Fe, Ni, Cr
and Cu on ultra thin layer of (0001) SmCo5 surfaces were
modeled and investigated. Electronic structure, exchange
coupling energy (J), and spin-orbit coupling (λ) of adatoms
deposited thin films were calculated using first principles
approach to understand the improvement in magnetic
anisotropy energy and Curie temperature (Tc).
explained in detail. Spin-orbit coupling of each atom is
calculated for (0001) SmCo5 slab and Sm atoms show
high λ (~1 eV) which contributes towards set high
magnetic anisotropy in SmCo5 slabs. Moreover, λ is
calculated for adatoms deposited slabs and the results
will also be discussed.
Keywords: SmCo5; Exchange coupling; Spin-orbit coupling;
Electronic structure; Density functional theory.
Introduction
Layered hexagonal SmCo5 is cleaved through
(0001) plane in order to get SmCo5 surface1. There are
two different possibilities of terminations at the surface
of the slab due to the presence of Co3 and SmCo2 atomic
layers, which are referred as A and B sub-layers and
their corresponding surfaces are named as A- and Bsurfaces, respectively. Optimized A(B)-surface is found
to be inwardly (outwardly) relaxed with higher (lower)
binding energy2. In the present work, the focus was on
the calculations of electronic structure, exchange
coupling, and spin-orbit coupling of surface modified
(0001) SmCo5 slabs by first principles density
functional theory using VASP package3 to determine
the effect of adatoms on magnetic anisotropic energy
(MAE) and Curie temperature (T c).
Fig. 1:(0001) surface of SmCo5 with Fe adatoms.
Conclusions
Electronic structure, exchange coupling, and
spin-orbit coupling of adatoms deposited on the (0001)
SmCo5 surface slabs were calculated. These results
showed that proper engineering of J and λ by adatoms
can led to significant improvement in MAE and Tc of
(0001) SmCo5 slabs.
Acknowledgment
Authors acknowledge DRDO for funding and
CSIR labs (CECRI and NCL) for HPC facility.
Results and discussions
Relaxations of surface slabs can be explained
by charge spill-over and layer resolved electronic
structure. Further, electronic structures were mapped for
the adatoms deposited surfaces and it was used to
explain the spin interactions and exchange coupling
between the surface and adatoms. Subsequently,
calculations of layer resolved J and site resolved λ of
surface modified (0001) SmCo5 slabs were carried out.
Calculated J values show that the A-surface has higher J
than B-surface. This is due to the transition metal atom
or Co-rich atoms at the A-surface. However, J value can
improve at B-surface when Co or Fe adatom is
deposited on B-surface and these results will be
References
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(1977).
[2] S. Selva Chandrasekaran, P. Murugan, P. Saravanan
and S. V. Kamat, "Surface termination dependent
structural and magnetic properties of (0001) SmCo5
slabs", Phys. Status Solidi (b) 250, 9, (2013), 18831887.
[3]G. Kresse and J. Furthmüller, "Efficient iterative
schemes for ab initio total-energy calculations using a
plane-wave basis set", Phys. Rev. B 54, 16, (1996),
11169-11186.