Magneto-ionic control of magnetism through voltage-driven carbon transport

Control of magnetism through voltage-driven ionic processes (i.e., magneto-ionics) holds potential for next-generation memories and computing. This stems from its non-volatility, flexibility in adjusting the magnitude and speed of magnetic modulation, and energy efficiency. Since magneto-ionics depends on factors like ionic radius and electronegativity, identifying alternative mobile ions is crucial to embrace new phenomena and applications. Here, the feasibility of C as a prospective magneto-ionic ion is investigated in a Fe-C system by electrolyte gating. In contrast to most magneto-ionic systems, Fe-C presents a reversible dual-ion mechanism: Fe and C act as cation and anion, respectively, moving uniformly in opposite directions under an applied electric field. This leads to a significant increase in saturation magnetization ( > 5-fold) with magneto-ionic rates larger than 1 emu·cm−3·s−1, and a 25-fold increase in coercivity. Since carbides exhibit minimal cytotoxicity, this introduces a biocompatible dimension to magneto-ionics, paving the way for the convergence of spintronics and biotechnology. There has been a recent interest in control of magnetism via ionic transport. The appeal of such magneto-ionic control lies in its extent, non-volatility and potential energy-efficiency, however, the number of systems showing such behaviour is limited. Here, Tan, Ma, and coauthors demonstrate magneto-ionic control through Carbon transport.