The last several decades have seen the development of electronic devices that have relied heavily on the downsizing of the transistor. This has helped to facilitate the technology for the small, powerful computers that are the basis of our modern information society.
Moore’s Law describes the growth of the number of transistors per unit area (and computing power) and predicts a doubling of transistors on a chip every two years. However, as we appear to be rapidly approaching the end of this trend where transistors are as small as atoms, and therefore cannot be shrunk any further, researchers are seeking other ways to continue progress in high-speed information processing.
To meet the ever-growing demands of computational power for electronic devices, we need to explore and identify radically new computing concepts. The concept of spintronics that creates a “spin”-based electronic technology which holds the potential to replace the current semiconductor technologies.
At the heart of the development of spintronic technologies are new discoveries and understanding of magnetic materials at the nanoscale. Hard disk drives exploit the nature of magnets and can store digital data reliably and cheaply. Spintronics has adopted this key advantage for data processing technologies. In this development, discoveries of new materials, together with an understanding of their materials properties, can bring about the breakthrough for energy-efficient new electronic devices.
In a paper recently published in Nature Electronics, Hidekazu Kurebayashi and colleagues explore a new class of materials, so-called the 2D layered van der Waals ferromagnets. These are a magnetic version of graphene and can potentially display novel properties which do not appear in their 3D forms.
Chromium germanium telluride (Cr2Ge2Te6) is a ferromagnetic insulator. Kurebayashi and colleagues applied electric fields on thin Cr2Ge2Te6 to study the role of the electric field. Cr2Ge2Te6 was successfully be made to be conductive by an electric field, similar to a field-effect-transistor function. They studied magnetism during the transition and discovered that the ferromagnetic transition temperature could be controlled by more than 100 K, meaning that it could electrically be switch on and off by applying electric fields. This was a major breakthrough for the project.
The background physics is rich and they continue to work on understanding the driving mechanism of 2D layered van der Waals ferromagnets and their role in future electrically switchable spintronic devices. This project could potentially lead to the production of a radically new class of nano-electronic devices which can store information as cheaply and reliably as hard-disc drives and at the same time process information by an electric field in a very energy-efficient manner.
This work has been carried out in collaboration with teams in National University of Singapore (Drs Ivan Verzhbitskiy and Goki Eda) and is supported by EPSRC grant “Spin Physics in Two-Dimensional Layered Ferromagnets” (EP/T006749/1).
Other relevant Links
UCL Electronic & Electrical Engineering
Other contributors: Schematic image of a 2D van der Waals magnet. Courtesy of Dr Ivan Verzhbitskiy.
