A joint research effort between the University of Alabama at Birmingham (UAB), Georgetown University, HZDR Dresden, and others has shown that it’s possible to switch magnetism states between ON and OFF in a new type of material that contains nitrogen by applying voltage, i.e., by connecting it to a battery. In doing so, it’s theoretically possible to generate or completely remove all magnetic features, leading to the possibility of being able to tune the magnetic strength of a material to specific applications.
The joint research team’s findings, published in the journal Nature Communications, describe how this discovery may open new avenues in applications like brain-inspired computing.
Controlling Magnetism with Current
In order to change the orientation of magnetics in electronics, it’s currently necessary to use an electrical current, the same one that powers the outlets in our homes.
The inherent problem here is that of heat generation: When a current is run through a material, it generates heat due to resistance and heats the material up. This heat is a form of energy that is lost to the environment and wasted. And as the demand for data storage increases year over year, this problem grows more pressing as devices shrink smaller in response, leading to even more energy losses.
A schematic representation of the electrolyte-gating process in the Co3O4 and CoN films. Image used courtesy of Nature Communications
In response to this problem, researchers have been racing to develop new materials and technology to control magnetism by applying voltage.
Controlling Magnetism with Voltage
Indeed, the control of magnetism using voltage is itself attracting interest and significant research activity due to its enormous potential.
It’s significant not only because it brings together contrasting elements of condensed-matter physics but also because it paves the way for new devices with unprecedented levels of performance. Indeed, progress is being made at such a pace that visions of novel spintronic applications that combine both memory and logical functionality at ultra-high processing speeds and ultra-low power consumption aren’t as farfetched as once was thought.
Magnetism in the Co-O and Co-N systems compared to Co-N formation energy. Image used courtesy of Nature Communications
While there are many approaches to the control of magnetism with voltage, one that’s particularly promising is magneto-ionics, where non-magnetic atoms are moved in and out of a magnetic material using voltage, thus altering its magnetic properties. It’s something that has established a core role in the control of magnetism with voltage among other methods like electric charge accumulation and intrinsic/extrinsic multiferroicity.
In their paper, the researchers demonstrate room-temperature voltage-driven nitrogen transport (nitrogen magneto-ionics) through the electrolyte gating of a copper-nitrogen (CoN) film, which is compared to oxygen magneto-ionics in cobalt(II,III) oxide (Co3O4).
The researchers were able to show that cobalt-nitride is non-magnetic on its own but forms a cobalt-rich magnetic structure when the nitrogen is removed with voltage. The process is both repeatable and durable, suggesting that it could be a promising system with potential uses in data writing and storage applications.
The research study also shows that the process requires less energy while also being faster than systems using alternative non-magnetic atoms like oxygen, thus increasing the possibility for energy savings.