# Magnetic Field Effect on the Handedness of Electrodeposited Heusler Alloy
## 3 Results  
Cyclic voltammetry on the solution containing the metal ions was performed between 0.85 V and \(-\)2.5 V with a scan rate of 50 mV/s. The results, reported in Figure 2 indicate that the deposition of the metals occurs together with the hydrogen evolution starting from \(-\)1 V. An anodic peak assigned to the oxidation of the alloy is present at \(-\)0.2 V.  
When we locate the south pole of the magnet below the electrode (i.e., the magnetic field is applied downward on the solution), both the peak related to the evolution of hydrogen and the anodic peak show higher currents (in absolute value) with respect to the measurement that was performed without the magnet. The opposite situation holds when the north pole of the magnet is placed below the electrode (i  
Figure 2: Cyclic voltammetry of the Heusler electroplating solution on the gold substrate in the absence and presence of the magnet under the electrode. Scan rate: 50 mV/s. A magnification of the anodic peach is reported in the inset. is applied upward). The variation in the current intensity on varying the magnetic field configuration suggests that the presence of a chiral species (D(+)-gluconate) in solution combined with the presence of a magnetic field may lead to the CISS effect. A confirmation of this hypothesis would require carrying out the experiment in the presence of the opposite enantiomer (I((-)-gluconate); however, this is beyond the scope of this paper. The Heusler alloy thick film samples were prepared in galvanostatic mode imposing a current density of 2.5 A/dm\({}^{2}\), which produced the best deposition according to [PERSON] and [PERSON] [14]. During the galvanostatic deposition, the applied potential varied around the value of \(-1.9\) V. The deposition process was carried out either in the absence of a magnet or in the presence of north and south magnetic fields. The value of the Lorentz force in our experimental setup is roughly \(\text{F}_{\text{L}}=125\) Nm\({}^{-3}\), considering that the magnetic field at a distance of 1 mm (the thickness of the silicon wafer) from the surface of the magnet was approximately B = 0.5 T and the current density j = 2.5 Adm\({}^{-2}\). On the samples that were deposited under magnetic field, a chiral spiral structure developed Figure 3a): a left-handed spiral was present when the north pole of the magnet was under the electrode; on the other hand, a right-handed spiral appeared in the case of the south pole. The samples were characterised morphologically and compositionally with SEM-EDS. No significative differences were detected in the three different samples. In Figure 3 SEM-EDS and XRF analysis of the sample without a magnet were reported by way of example. Figure 3: (**a**) Photos of the obtained films. The contrast was increased to make evident the opposite handedness of the samples obtained with the opposite magnetic field; (**b**) SEM, (**c**) EDS, and (**d**) XRF analysis of the deposit obtained without the magnet. The SEM analysis (Figure 3b) shows the presence of growth nuclei with dimensions between 100 nm and 200 nm. The EDS analysis (Figure 3c) provides the composition of the coating: 29.8 wt% Co, 24.5 wt% Fe, and 45.7 wt% Sn were found, which correspond to a Co:Fe:Sn stoichiometric ratio of 2.0:1.7:1.5. A cobalt deficiency was found that was relative to the expected amount 2:1:1. The composition that was found with EDS was used to obtain the thickness of the deposit from the XRF spectra (Figure 3d), following a procedure that was previously described in [35, 36, 37]. The mean thickness of the sample that was prepared without the magnet was 0.46 \(\upmu\)m; the sample on the south pole of the magnet had a thickness of 0.36 \(\upmu\)m, while the sample on the north pole was 0.34 \(\upmu\)m.  
The Au-Si substrate and the samples with the deposit were analysed with XRD (Figure 4).