Nanomagnetic devices are non-volatile, energy efficient, and can accommodate non-linear magnetization dynamics that are tunable by various external stimuli. These characteristics make them ideal to meet the requirements for future computing. Our aim is to bring significant innovations in the field of nanomagnetism and spintronics by exploring new magnetic materials, nanostructures, novel switching schemes and complex magnetization dynamics which could ultimately lead to successful implementation of energy efficient nanomagnetic devices to be integrated into next generation computing platforms. To achieve this, our experiments will span growth, nanofabrication, and advanced structural and magnetic characterization techniques including magnetometry, spin-transport, and magnetic imaging.
Some current projects are briefly described below.
Magneto-ionics
Magneto-ionics relies on electric field induced ion migration towards or away from a magnetic layer. My research focus is to optimize magneto-ionic systems with existing materials as well as explore new materials towards faster and reversible control. I also investgate magneto-ionic devices for reservoir computing applications. Our preliminary work on integration of MTJs and magneto-ionics has also shown promising signs towards controlling tunneling magnetoresistance (TMR).
Magnetic Skyrmions
Magnetic skyrmions have attracted interest for racetrack memory as they need orders of magnitude smaller current density to move compared to domain walls. However, I have demonstrated that switching skyrmions fixed in space with an electric field can lead to more energy-efficient and scalable memory devices. Voltage control of skyrmions can also be utilized for neuromorphic devices such as resonate and fire neurons.
3D Nanowire Network
Extending the nanomagnetic structure in the third dimension can expand the functionalities manifold by stabilizing more intricate spin textures and unlocking complex magnetization dynamics. The 3D nature also allows fabrication of devices that mimic the real brain structure. Hence, 3D nanomagnetic systems are an ideal platform to implement real brain-like functionalities. My previous work has already demonstrated the potential of a 3D nanomagnetic framework—interconnected nanowire (NW) networks—for neuromorphic applications. I am currently exploring detailed spin textures and magnetization dynamics in 3D and curved geometries.
3D Curved Geometry
Designing curvature in three-dimensional (3D) magnetic nanostructures enables controlled manipulation of local energy landscapes, allowing for the modification of noncollinear spin textures relevant for next-generation spintronic devices. We experimentally investigate 3D spin textures in a in magnetic systems exhibiting strong perpendicular magnetic anisotropy (PMA). Our findings demonstrate that introducing curvature into magnetic nanostructures provides a powerful strategy for tailoring complex magnetic behaviors, paving the way for the design of advanced 3D racetrack memory and neuromorphic computing devices.
Straintronics
One method of electric field control of magnetization is to generate a strain in a piezoelectric layer by applying an electric field to it, transfer this strain to the magnetostrictive nanoscale magnet or magnetostrictive soft layer of a magnetic tunnel junction (MTJ) deposited on the piezoelectric, thus controlling its magnetization state through inverse magnetostriction (Villari effect). Such strain mediated electric field control of magnetization offers an extremely energy-efficient method of writing the magnetic state (~100 aJ/bit).
Surface Acoustic Waves
SAW generates time varying strain. When multiple nanomagnets are delineated on a piezoelectric substrate or film, cumbersome lithography with challenging alignment capability is required to address each nanomagnet separately by local electrodes. Furthermore, this approach would increase the device footprint. Using SAW to clock magnetostrictive nanomagnets sequentially (one by one), on the other hand, could eliminate the need for high resolution lithography, thus offering a more practical and cost effective solution.