The magnetic properties of nanoscale magnetic structures with at least one dimension at the nanometre level, such as ultrathin magnetic metal films (2D), strips (1D) and islands (quasi-0D) are conventionally manipulated by magnetic fields and electric currents. Much is now known about the magnetization reversal of such structures driven by magnetic field- and current-induced torques, and how it may be exploited in magnetic data storage technology or magnetic field sensors. While nanomagnetic devices have the advantages of retaining memory in the off-state and being insensitive to radiation, making technology such as Magnetic Random Access Memories (MRAM) competitive in niche markets, the main obstacle to a more widespread implementation is the large power density, as well as just overall power, required for the magnetization reversal and the subsequent incompatibility with device architectures, and associated energy wastage. In order to create more efficient devices, researchers over the last few years have investigated the effect of E-fields on
nanomagnetic structures, with pioneering studies predicting that in combination with a low level of conventional stimulus (magnetic field or electric current), or even using E-fields alone, the reversal of magnetization may be achieved at low power. This has led to spintronic circuits containing magnetic materials modified by E-fields becoming competitive with contemporary electronic integrated circuits (ICs) in terms of their switching energy, and being better in terms of implementing complex logic functions with smaller numbers of elements. The key factor towards making technologies based on nanomagnetic structures competitive with CMOS and other approaches is thus to enhance and diversify the E-field control of magnetism.
In our project we have expanded the exploration of E-field control of magnetism in nanomagnetic structures by using three different schemes: strain, gating and light. We have advanced the field of E-field control of magnetism by showing magneto-ionic gating in a variety of materials and device structures which allowed for the manipulation of key properties like magnetic anisotropy and magnetic domain wall velocity. The strain control of the magnetic response has also shown positive results with different strain configurations, planar and vertical constant strain, as well as dynamic strain in the form of surface acoustic waves. Within the light scheme great progress was made to optimise the energy efficiency of all optical switching and its integration into photonic circuits. Both theory and experiments were used to understand and test these novel schemes of control of magnetism in nanostructures. In addition, fist steps have been taken to use this knowledge and technological development in applications, for example, in the design and packaging of magnetic sensors.
Within this exciting scientific framework, our project significantly enhanced the career prospects of its ESRs through a uniquely cross-linked and research-focused training programme. The intertwining of three scientific approaches to applying E-fields to nanomagnetic structures successfully produced young researchers with a breadth of expertise that will be vital to sustaining the research and development of electronics for GreenIT in the EU in the future.
