Control of Magnetism with Electrochemical Potential

Magnetic ultrathin films (thickness of only a few atomic plane)s are of special interest because their magnetic anisotropy, i.e. the direction of magnetization at rest, is controlled by interfaces with substrate and capping layer [1]. Such films are involved in GMR and TMR junctions which are the building blocks to design memories and logic circuits [2]. Device operation relies on ability to reverse the magnetization within one component at a time. The best method is currently Spin Torque Transfer, STT, by injection of spin polarized current. The method allows addressing magnetization reversal in one single component but requires high current density (1010 A/m2) that leads to Joule heating [3]. Physical electrochemistry and electrodeposition have a role to play in above context because electrochemical growth of epitaxial films is almost routine technique. In situ STM and in situ SXRD showed that nucleation and growth is now well controlled [4] [5] [6]. Moreover, the development of in situ magnetic properties (magnetooptical Kerr Effect, MOKE) [7] has been a decisive step forward to correlate structure / morphology with magnetic anisotropy (MA). This presentation will focus on the use of electrochemical interface to tailor MA with applied voltage [8] [9] [10] which is most promising approach to design ultralow power consumption devices [11]. Newest results will be discussed. References: [1] B. Dieny and M. Chshiev, Perpendicular magnetic anisotropy at transition metal/oxide interfaces and applications, Rev. Mod. Phys. in press (2017). [2] C. Chappert et al., The emergence of spin electronics in data storage, Nat Mater 6 (11), 813 (2007). [3] L. Robert et al., The 2014 Magnetism Roadmap, Journal of Physics D: Applied Physics 47 (33), 333001 (2014). [4] L. Cagnon et al. Enhanced interface perpendicular magnetic anisotropy in electrodeposited Co/Au(111) layers, Phys. Rev. B 63 (10), 104419 (2001). [5] C. A. Lucas et al., Film and Interface Atomic Structures of Electrodeposited Co/Au(111) Layers: An in Situ X-ray Scattering Study as a Function of the Surface Chemistry and the Electrochemical Potential, The Journal of Physical Chemistry C 120 (6), 3360 (2016). [6] H. F. Jurca et al., Epitaxial Electrodeposition of Fe on Au(111): Structure, Nucleation, and Growth Mechanisms, The Journal of Physical Chemistry C 120 (29), 16080 (2016). [7] P. Allongue and Fouad Maroun, Electrodeposited magnetic layers in the ultrathin limit, MR Bulletin 35 (10), 761 (2010). [8] N. Tournerie et al., Influence of the surface chemistry on the electric-field control of the magnetization of ultrathin films, Phys. Rev. B 86 (10), 104434 (2012). [9] N. Tournerie et al., Probing the electrochemical interface with in situ magnetic characterizations: A case study of Co/Au(111) layers, Surf. Sci. 631 (0), 88 (2015). [10] N. Di et al., Influence of controlled surface oxidation on the magnetic anisotropy of Co ultrathin films, Applied Physics Letters 106 (12), 122405 (2015). [11] F. Matsukura et al., Control of magnetism by electric fields, Nat Nano 10 (3), 209 (2015).