Ab initio investigations of magnetic properties of ultrathin transition ...

66 4 Collinear magnetism of 3d-monolayers on Rh substrates
Table 4.1: Summary of Relaxations, Δd12 and Δd23, 3d and Rh(I) magnetic moments,
MCA, OMA and total energy differences results of 3d-TMs monolayers on Rh(001) substrate.
FM:
V Cr Mn Fe Co Ni
Δd12 (%) −7.4 −11.7 −7.4 −7.4 −13.3 −12.8
Δd23 (%) +6.9 +6.7 +3.0 +2.2 +2.8 −0.7
3d moments [μB] 0.23 2.98 3.76 3.01 2.01 0.73
Rh(I) moments [μB] 0.00 −0.10 +0.18 +0.26 +0.46 −0.35
MCA [meV/3d] +0.03 −0.19 +0.27 +0.75 −0.28 −0.86
OMA Δml [μB] 0.00 −0.002 +0.001 −0.001 −0.041 −0.025
AFM:
Δd12 (%) −7.4 −5.2 −9.6 −12.8 −13.5 −13.5
Δd23 (%) +6.9 +3.2 +3.8 +4.5 +2.2 +0.7
3d moments [μB] 0.00 2.94 3.63 2.93 1.73 0.00
Rh(I) moments [μB] 0.00 0.00 0.00 0.00 0.00 0.00
MCA [meV/3d atom] - +0.18 −0.11 −0.19 −0.63 -
OMA [μB] 0.00 +0.014 −0.022 −0.015 −0.056 0.00
EAF M−EFM [meV/3d] +6 −155 −346 −55 +162 +23
4.3 3d-Monolayers on Rh(111) Substrate:
Magnetic properties of V, Cr, Mn, Fe, Co and Ni monolayers on the hexagonal Rh(111)
surface will be explained in this section. We followed the same procedure as in the previous
section (4.2). By studying the magnetic properties of (111)-oriented surfaces, we will see the
effect on the magnetic properties when increasing the coordination number in the magnetic
layer from 4, in square lattices, to 6 in hexagonal lattices. The (111) results, especially
for Fe, will be helpful to investigate its magnetic ground state, especially since we have
hexagonal substrates, where frustrations may occur due to their triangular lattices. All
calculations were performed in the same way as outlined in sec. 4.2.1. The computational
parameters were also not changed, keeping in mind that we have hexagonal k-point mesh,
with 36 k�-points in the 2DIBZ.
4.3.1 Relaxations and magnetic moments:
The structural relaxations were performed for V, Cr, Mn, Fe, Co, and Ni monolayers on
Rh(111) substrate for two magnetic configurations, FM (with one atom/unit cell) and the
RW-AFM (with 2 atoms/unit cell) as illustrated in figure 4.14. For Cr (V), there was no
stable FM (AFM) collinear solution. The FM and AFM relaxations of 3d/Rh(111) are