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

6.3 Co atomic chain on Rh(664): 111
E θ,φ −E 0,0 [meV/Co]
Co
m [μΒ ] l
Rh
m [μΒ ]
l
0.5
0.0
−0.5
0.16
0.14
0.12
0.10
0.08
0.012
0.008
75°
(a)
(b)
(c)
Co
(θ,0)
(-90,φ)
ΣRh
60°
71°
0.004
−90 −60 −30 0 30 60 90
(degree)
Figure 6.6: Left: Energy of the relaxed Co decorated Rh step edge as a function of the
spin-quantization axis SQA calculated with the force theorem (a), Co orbital moments (b),
and the sum of all Rh orbital moments (c). Full lines correspond to a variation of the SQA
in the xz plane (perpendicular to the wire) (see Fig. 6.5), dashed lines correspond to a
variation in the xy plane (terrace plane). Right: A 3D plot of the MCA values simulated
to be proportional to a size of green (red) cone for negative (positive) energies with respect
to the terrace surface normal energy (black solid circle).
the experimental results. In our case, Co/Rh(664) was not experimentally investigated, we
can’t verify our results. Instead we compare our relaxed MCA results to the Co/Pt(664)
relaxed results to find out some connection which might lead us to a reasonable understanding
of some chemical trends and the substrate effect on the Co atomic chain MCA,
as we did for the two dimensional case in last section (6.2).
From our MCA calculations at the high symmetry points, (0, 0), (90, 0), and (90, 90), we
retrieved the spin and orbital moments of Co atoms and their Rh neighboring atoms, then
we compare them to Co/Pt(664) results from Ref. [151], as shown in table 6.2. As expected,
Co spin moments increased from 1.97 μB on Rh to 2.10 μB on Pt, with increasing the d-band
filling. We find larger Rh surface induced spin moments than of Pt, although Rh has smaller
magnetic susceptibility (+102 × 10 −6 cm 3 mol −1 ) than Pt (+193 × 10 −6 cm 3 mol −1 )[155].
Additionally, the large induced Rh spin and orbital moments did not compensate Co spin
and orbital moments, as Pt spin and orbital moments did. Furthermore, we see that the