## 3 Electrodeposition
### Properties Relevant to Applications
#### 3.3.4. Magnetic Properties  
The magnetic properties of high-entropy alloys (Table 4) have also attracted attention due to their tunability through compositional design and potential applications such as non-volatile memory, magnetic sensors, and nano-transformers [16; 26; 43; 47; 43].  
[PERSON] et al. [16] reported the magnetic properties of the first electrodeposited HEA coating. The single-phase BiFeCoNiMn alloy, produced potentiostatically from an organic bath, exhibited soft magnetic and paramagnetic behavior, while annealed alloys demonstrated hard magnetic properties. This change in magnetic properties was attributed to the variation in inter-granular distance between nanocrystals; when the grains are well separated (beyond the exchange correlation length), magnetic hardening is favored, whereas increased grain density reduces the inter-granular spacing, leading to magnetic softening. Other changes in magnetic properties caused by annealing were also observed by [PERSON] et al. [26] for FeNiWMoMn alloys. They found variable coercivity in alloys deposited for different times (30-90 min), with the hysteresis loop for the as-deposited alloy being much wider than for the annealed alloy, indicating lower coercivity and hard magnetic properties in the non-annealed state. These changes during heat treatment (200 \({}^{\circ}\)C) were attributed to the relaxation of internal stresses and a decrease in defect density.  
[PERSON] et al. [43] investigated Co20 Cu21 Fe19 Ni17 Zn23 alloys electrodeposited using pulse plating from an aqueous solution. The dual-phase (FCC + BCC) alloy with nanocrystalline grains (5-20 nm) exhibited high saturation magnetization (82 emu/g) and relatively low coercivity (19 Oe), indicating soft magnetic behavior. The relatively high saturation magnetization of these HEA thin films was primarily attributed to their composition of ferromagnetic elements (Fe, Co, Ni), even with the addition of diamagnetic elements such as Cu and Zn, as well as their two-phase crystalline structure. In contrast, a single-phase crystalline structure, due to its symmetry, can potentially reduce saturation magnetization by neutralizing some atomic magnetic moments. Additionally, soft magnetic properties are generally enhanced in nanocrystalline materials compared to their microcrystalline counterparts.  
In turn, [PERSON] et al. [47] investigated the effect of pulsed current parameters (duty cycle, frequency) on the properties of FeCoNiMoW alloys produced from a sulfate-citrate bath. They observed that increasing the frequency from 10 to 100 Hz and decreasing the duty cycle from 80% to 10% resulted in higher Mo and W content and a greater amorphous phase in the HEA deposits. Additionally, as frequency increased and duty cycle decreased, the surface of the coatings became more compact. All coatings exhibited soft magnetic properties. The highest magnetic saturation (107 emu/g) was observed at a frequency of 10 Hz and a duty cycle of 10%, with the alloy showing the highest iron and cobalt content (Fe33 Co30 Ni15 Mo13W9), while the lowest coercivity (7 Oe) was obtained at a frequency of 100 Hz and a duty cycle of 40%, with the alloy showing the lowest cobalt content (Fe29 Co25 Ni22 Mo14W9).