Supplementary Information
Figure S1. (a) & (b) are reciprocal space mapping (RSM) scans on PZT/SRO/STO
and PZT/LSCO/STO showing that fully c-oriented PZT has been attained in both
heterostructure systems.
Figure S2. High-resolution XRD performed on PZT/SRO/STO & PZT/LSCO/STO.
The sole presence of (00l)-type peaks indicate that the films are fully c-oriented.
Figure S3. (a) & (b) are histograms for Ag particle size distributions on
PZT/SRO/STO and PZT/LSCO/STO, respectively. The median particle size on
PZT/SRO/STO is 12% larger than the median particle size on PZT/LSCO/STO.
S4. Numerical calculation for the temperature rise in SRO & LSCO
electrodes cause by UV absorption.
In order to estimate the heating caused by photon absorption at the
PZT/electrode interface, first one needs to calculate the intensity profiles of the
incident laser energy. Figure 1 compares the UV intensity profile as a function of
penetration depth for the PZT/LSCO/STO (red) and PZT/SRO/STO (blue)
heterostructures used in this paper.
The UV intensity drop within each respective layer is calculated using1:
I = (1-R)I0 e-αz
(1)
where I is the UV intensity at depth 𝑧, R is the reflectivity at an interface, I0 is the
laser intensity at an interface before the occurrence of reflection and 𝛼 is the
absorption coefficient.
The absorption coefficient of PZT2 has been reported to be 3.8x105cm-1. The
absorption coefficient for SRO is estimated as 1.2×105 cm-1 using the data
provided in Koster et al.3, For LSCO we used the closest perovskite compound
(CMR manganites)4 ~3.8×105cm-1. The reflectance values of PZT, SRO and LSCO
and STO5 at 248 nm obtained from literature are given in Table 1.
Figure S4. UV intensity profile as a function of penetration depth for the
heterostructures used in this paper.
To calculate the respective temperature rise cause by photon absorption at the
electrode, we first calculated the heat diffusivity, D = k / Cp r 6 ,which governs the
heat dissipation rate in a solid6.
Following the model developed by Bharadwaja et al.,6 the characteristic heat
diffusion length, (x) = (2Dτ)0.5, per laser shot is then determined.
The temperature rise induced by each electrode can then be calculated using:
DT =
(1- R)I t
C p r (2Dt )0.5
(2)
where R, I, τ, Cp, ρ and D are the reflectivity, laser intensity, pules width (20ns),
specific heat, material density and heat diffusivity, respectively.
SRO
LSCO
Incident Laser Intensity (I0)
on the
PZT Layer
4.55 W/cm-2
4.55 W/cm-2
Laser Intensity (I1) Entering
The PZT after reflection at
air/PZT interface. The
reflectance(R) of PZT is 19%6.
3.68 W/cm-2
3.68 W/cm-2
2.51 W/cm-2
2.51 W/cm-2
25%
7%
I1= I0(1-RPZT)
Incident Laser Intensity (I2)
on Electrode (after PZT
absorption)
I2= I1 e-αz
Where a is the absorption
coefficient of PZT2 and z is the
PZT thickness [10 nm]
Reflectance7,8 (Relectrode)
Laser Intensity (I3) Entering
the Electrode (after reflection
at PZT/electrode interface)
1.88x104 Wm-2
2.33x104 Wm-2
Theoretical Density of
Electrode Material 9
6.489×103 kg m-3
6.55×103 kg m-3
Thermal Conductivity10,11
5.72 Wm-1 K-1
3.75 Wm-1 K-1
Heat Diffusivity
1.115×10-6 m2s-1
1.145×10-6 m2s-1
Specific Heat
Capacitance(Cp )10,12
790J kg-1 K-1
449J kg-1 K-1
Characteristic Heat Diffusion
Length (2Dτ)0.5
211nm
214nm
ΔT (calculated from equation
2)
3.47×10-4 K
7.4×10-4 K
I3= I2(1-Relectrode)
D = k / Cp r
Table 1. Calculations of the temperature rise within each respective
electrode.
It is found that the temperature rise caused by both electrodes is negligible. This
is primarily because the majority of the laser energy is absorbed by the PZT layer.
Moreover, both electrode materials have similar optical and thermal parameters.
In conclusion, the thermal contribution from the electrodes is unlikely to be the
cause of the observed difference in reaction rate of Ag+ ion reduction.
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