SUPPORTING INFORMATION
Non-magnetic organic/inorganic spin injector at room temperature
Shinto P Mathew1, Prakash Chandra Mondal,1 Hagay Moshe2, Yitzhak Mastai,2 and Ron
Naaman1*
1) Department of Chemical Physics, Weizmann Institute, Rehovot 76100, Israel
2) Department of Chemistry and the Institute of Nanotechnology, Bar-Ilan University,
Ramat-Gan 52900, Israel
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Device fabrication and characterization:
The device is based on a vertical structure in which the bottom electrode is made from gold
and coated with a self-assembled monolayer (SAM) of chiral molecules on top of which an
Al2O3 layer is deposited, followed by a layer of nickel. The devices (Figure S1) were
prepared by photolithography, followed by e-beam evaporation, on a silicon substrate with
thermally grown 300 nm SiO2 (<100>, >400Ω per cm2). The 1 µm-wide, 2 mm-long and 60
nm-thick Au line was evaporated on an 8 nm-thick Cr adhesion layer. SAM of oligopeptide
or L and D cysteine were adsorbed on the Au electrode. An Al2O3 layer with a thickness of
about 2 nm was deposited on top of the SAM at 100oC by atomic layer deposition (Fiji F200,
Cambridge Nanotech.). The top 150 nm-thick, 50 µm-wide Ni line was evaporated without
any adhesion layer. 150 nm-thick gold contact pads for wire-bonding were evaporated. A
high-resolution scanning electron microscopic (SEM) SE2-detector image was produced with
LEO-Supra-55VP.
Figure S1: SEM image of the device. The thin line is the gold line and the wide one is the
nickel.
2
Polarization modulation-infrared reflection-absorption spectroscopy (PMIRRAS)
Formation of the monolayer and the Al2O3 layer was confirmed by PMIRRAS spectra.
Infrared spectra were recorded in PM-IRRAS mode using a Nicolet 6700 FTIR, at an 80º
incidence angle, equipped with a PEM-90 photoelastic modulator (Hinds Instruments,
Hillsboro, OR). Figure S2 shows the spectra recorded on SAM of oligopeptide on gold and
for Al2O3-coated SAM. The spectrum of the SAM alone shows all the characteristic peaks of
the oligopeptides and the spectrum of the Al2O3-coated SAM shows the peak corresponding
to the Al2O3 and that of the intact SAM. For example, the spectrum of the oligopeptide
exhibits a stretching frequency at 1668 cm-1, which is related to the amide I band, whereas the
peak at 1543 cm-1 is due to the amide II band. This result confirms the formation of the
oligopeptide monolayer on the Au surface. A stretching frequency with high intensity is
observed at 931 cm-1 due to Al2O3. Figure S3 shows the spectrum recorded with SAM made
from L-cysteine on gold. The strong peaks at 2917 and 2849 cm-1 are assigned to the
asymmetric and symmetric C–H stretching frequency of the –CH2 group present in the
cysteine. The peaks at 1713 and 1643 cm-1 are due to the carbonyl (C=O) stretching
frequency in the carboxylic group and N-H bending in NH2, respectively.
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SAM of oligopeptide on Au
Al2O3 coated SAM on Au
3
2
Al2O3
4
Amide 2
Amide 1
Intensity (Arb. unit)
5
1
0
1800
1600
1400
1200
1000
800
-1
Wave number (cm )
Figure S2: The PM-IRRAS spectra of the SAM made from the oligopeptide on Au (blue)
and the Al2O3-coated SAM on Au (red).
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Intensity (arbb. unit)
L-Cysteine
3000
2950
2900
2850
2800 1800
1700
1600
1500
Wave number (cm-1)
Figure S3: The PM-IRRAS spectra of SAM of L-cysteine on Au.
Static Contact Angle (CA) measurements
Static contact angle measurements were performed with a goniometer (Rame-Hart) and micro
syringe droplets with ca. 4 μL deionized water (Millipore, Inc.). The measurements were
performed immediately after the gold was functionalized with cysteine. The contact angle
measured was 22±5⁰, which confirms the formation of a hydrophilic layer.
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