Artificial Spin Ice
Artificial spin ice, known for its geometrical frustration behavior which refers to the disordered magnetization states found in topologically well-ordered structures, has been extensively investigated. This unique property, resulting from the competition between neighboring interactions, is essential in the development of a wide range of potential applications such as information storage, signal propagation and logic devices.
We mainly focus on the design of new artificial spin ice structures and characterization of their static and dynamic magnetic properties.
Spin waves, representing a phase-coherent precession of microscopic vectors of magnetization in magnetic medium, can be considered as a magnetic analogue of a sound or light wave. Interest in propagating spin-wave based devices has grown in the last few years largely due to the concurrent advances in nanofabrication and characterization techniques. The wavelength of spin waves is several orders of magnitude, shorter than that of electromagnetic waves. Therefore, spin-wave based devices offer better prospects for miniaturization in the gigahertz to terahertz range. In addition, spin-wave devices are made from non-volatile memory elements, and hence, their integration will enable programmable devices with ultrafast re-programming at the sub-nanosecond time scale.
A clear reinvigoration of interest has been seen in the study of static and dynamic phenomena of magnetic vortices and other topologies, ever since its first experimental evidence was reported in 1999 during the study of nanodisks with varying diameters and thicknesses. These topologies present potential application in the field of magnetic data storage, logic devices and sensors. With improvements in fabrication techniques, the scope of study involving magnetic vortices is expanding to nanodisks which were difficult to examine before. In our ongoing research, we examine stepped nanodisks and nanodisks with high thickness to diameter aspect ratio.
Resistance switching (RS), which refers to the alternation of conductance in solids triggered by an external electrical field, is a very fundamental physical phenomena observed since the 1960s. Also termed as electroresistance, it is a hot topic of research over the past decade due to its enormous potential as an ultra-high density and high speed nonvolatile memory.
We demonstrate co-sputtering as a new route of interface engineering to enhance resistive switching characteristics and investigate electroresistance in the OFF state in detail. We also study the change in the surface temperature of the oxide layer to understand the role of thermochemical reactions initiated by Joule heating during SET-RESET process.