AbstractThe growth of SrRuO$$_3$$
3
(SRO) thin film with high-crystallinity and low residual resistivity (RR) is essential to explore its intrinsic properties. Here, utilizing the adsorption-controlled growth technique, the growth condition of initial SrO layer on TiO$$_2$$
2
-terminated SrTiO$$_3$$
3
(STO) (001) substrate was found to be crucial for achieving a low RR in the resulting SRO film grown afterward. The optimized initial SrO layer shows a c(2 $$\times $$
×
2) superstructure that was characterized by electron diffraction, and a series of SRO films with different thicknesses (ts) were then grown. The resulting SRO films exhibit excellent crystallinity with orthorhombic-phase down to $$t \approx $$
t
≈
4.3 nm, which was confirmed by high resolution X-ray measurements. From X-ray azimuthal scan across SRO orthorhombic (02 ± 1) reflections, we uncover four structural domains with a dominant domain of orthorhombic SRO [001] along cubic STO [010] direction. The dominant domain population depends on t, STO miscut angle ($$\alpha $$
α
), and miscut direction ($$\beta $$
β
), giving a volume fraction of about 92 $$\%$$
%
for $$t \approx $$
t
≈
26.6 nm and $$(\alpha , \beta ) \approx $$
(
α
,
β
)
≈
(0.14$$^{\mathrm{o}}$$
o
, 5$$^{\mathrm{o}}$$
o
). On the other hand, metallic and ferromagnetic properties were well preserved down to t$$\approx $$
≈
1.2 nm. Residual resistivity ratio (RRR = $$\rho ({\mathrm{300 K}})$$
ρ
(
300
K
)
/$$\rho ({\mathrm{5K}})$$
ρ
(
5
K
)
) reduces from 77.1 for t$$\approx $$
≈
28.5 nm to 2.5 for t$$\approx $$
≈
1.2 nm, while $$\rho ({\mathrm{5K}})$$
ρ
(
5
K
)
increases from 2.5 $$\upmu \Omega $$
μ
Ω
cm for t$$\approx $$
≈
28.5 nm to 131.0 $$\upmu \Omega $$
μ
Ω
cm for t$$\approx $$
≈
1.2 nm. The ferromagnetic onset temperature ($$T'_{\mathrm{c}}$$
T
c
′
) of around 151 K remains nearly unchanged down to t$$\approx $$
≈
9.0 nm and decreases to 90 K for t$$\approx $$
≈
1.2 nm. Our finding thus provides a practical guideline to achieve high crystallinity and low RR in ultra-thin SRO films by simply adjusting the growth of initial SrO layer.
A Comparison of Methods for Computing the Residual Resistivity Ratio of High-Purity Niobium
