Electrical control of magnetism by electric field and current-induced torques

The remanent magnetization of ferromagnets has long been studied and used to store binary information. While early magnetic memory designs relied on magnetization switching by locally generated magnetic fields, key insights in condensed matter physics later suggested the possibility of doing it by electrical means instead. In the 1990s, Slonczewski and Berger formulated the concept of current-induced spin torques in magnetic multilayers through which a spin-polarized current generated by a first ferromagnet may be used to switch the magnetization of a second one. This discovery drove the development of spin-transfer-torque magnetic random-access memories (MRAMs). More recent fundamental research revealed other types of current-induced torques named spin-orbit torques (SOTs) and will lead to a new generation of devices including SOT MRAMs and skyrmion-based devices. Parallel to these advances, multiferroics and their magnetoelectric coupling, first investigated experimentally in the 1960s, experienced a renaissance. Dozens of multiferroic compounds with new magnetoelectric coupling mechanisms were discovered and high-quality multiferroic films were synthesized (notably of BiFeO₃), also leading to novel device concepts for information and communication technology such as the magnetoelectric spin-orbit (MESO) transistor. The story of the electrical switching of magnetization, which is discussed in this review, is that of a dance between fundamental research (in spintronics, condensed matter physics, and materials science) and technology (MRAMs, MESO transistors, microwave emitters, spin diodes, skyrmion-based devices, components for neuromorphics, etc.). This pas de deux has led to major scientific and technological breakthroughs in recent decades (such as the conceptualization of pure spin currents, the observation of magnetic skyrmions, and the discovery of spin-charge interconversion effects). As a result, this field has not only propelled MRAMs into cons. Authors: Fert, Albert [Laboratoire Albert Fert, Palaiseau (France); Centre National de la Recherche Scientifique (CNRS), Palaiseau (France); Thales, Palaiseau (France); Univ. Paris-Saclay, Palaiseau (France); Univ. of the Basque Country (UPV/EHU), San Sebastian (Spain); Donostia International Physics Center (DIPC), San Sebastian (Spain)]; Ramesh, Ramamoorthy [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]; Garcia, Vincent [Laboratoire Albert Fert, Palaiseau (France); Centre National de la Recherche Scientifique (CNRS), Palaiseau (France); Thales, Palaiseau (France); Univ. Paris-Saclay, Palaiseau (France)]; Casanova, Fèlix [CIC nanoGUNE BRTA, Donostia (Spain); Basque Foundation for Science, Bilbao (Spain). IKERBASQUE] (ORCID:0000000303162163); Bibes, Manuel [Laboratoire Albert Fert, Palaiseau (France); Centre National de la Recherche Scientifique (CNRS), Palaiseau (France); Thales, Palaiseau (France); Univ. Paris-Saclay, Palaiseau (France)] (ORCID:0000000267043422). DOE Contract: AC02-05CH11231. Subjects: 36 MATERIALS SCIENCE