Antiferromagnetic FeMn alloys electrodeposited from chloride-based electrolytes

Abstract

The capability of synthesizing Fe-based antiferromagnetic metal alloys would fuel the use of electrodeposition in the design of new magnetic devices such as high-aspect-ratio spin valves or new nanostructured hard magnetic composites.

Analysis of the electrodeposition process of Fe–Mn films from sulfate electrolytes

“…The inclusion of MnSO 4 drastically reduces the current in the range from about −1.30 V up to −1.56 V. Only for potentials more negative than −1.56 V the current presents significant values, which can be attributed to Mn reduction. This value is below the theoretical value for Mn 2+ reduction expected from the Pourbaix diagram [24], but close to the normally observed experimentally [7,14,15]. A light gray deposit with metallic aspect is clear seen when the applied potential is below −1.56 V. It should be noted that the amount of MnSO 4 included in the solution (C Mn =0.6 M) is of the same order of magnitude of the amount of (NH 4 ) 2 SO 4 , in a way that its addition changes significantly the solution viscosity affecting the diffusion.…”

“…Due to the great importance of metallic alloys in a wide range of applications, the electrodeposition of alloys has been the focus of many publications for decades [1][2][3][4][5][6][7]. The process of electrodeposition has many advantages in specific applications as compared with other methods as fusion or vapor deposition, and furthermore it is usually less expensive.…”

“…Fe-Mn, in particular, is an alloy used in several applications from galvanic sacrificial protection of steel [1,12] to spintronics devices [13], but lacks better methods to be electrochemically deposited in the appropriated composition and structure. Fe-Mn codeposition is very susceptible to changes in the electrolytic baths and is hard to be properly controlled due to the very low potential for the reduction of Mn [7,14,15].…”

“…The addition of (NH 4 ) 2 SO 4 has been pointed out in the literature to benefit of the efficiency and uniformity of Fe-Mn deposit [1,7]. We have also investigated the effects of this additive at different concentrations.…”

“…The process of electrodeposition has many advantages in specific applications as compared with other methods as fusion or vapor deposition, and furthermore it is usually less expensive. However, many difficulties remain not completely overcome, as the precise control of the alloy composition [1,2,7] and a better understanding of the kinetics of the process [8][9][10][11]. Fe-Mn, in particular, is an alloy used in several applications from galvanic sacrificial protection of steel [1,12] to spintronics devices [13], but lacks better methods to be electrochemically deposited in the appropriated composition and structure.…”