This award from the Condensed Matter Physics program of the Division of Materials Research supports a project to create artificial magnetic structure called spin ice/vortex ice hybrid systems. Spin ice is the magnetic analog of the atomic ordering in the (H2O) ice. In addition to creating the structure the project includes tuning the degree of magnetic ordering or "crystallinity" of the spin ices and vortex ices. The project provides novel platforms to explore new properties controlled by the degree of crystallinity. The research provides a foundation for understanding and manipulating the new complex and collective effects that are expected in these artificial ices in a controllable way. This project also supports the training of graduate students, enhancing their academic knowledge and improving their likelihood to succeed in future careers in academia, industry, or government.
Spin ice systems are magnetic analogues of the old problem of how hydrogen atoms order in the ice (H2O) lattice and have been intensively investigated. This project examines both square and kagome vortex ice systems created by patterning superconducting MoGe thin films with desired configurations of nanoscale hole arrays. The scientists seek to obtain direct images via magnetic force microscopy (MFM) of vortex ices; conduct transport measurements in a cross-bar shaped setup to reveal their dynamic properties; and couple simulations with tailored experiments to divulge information on the vortex phases in a driven vortex system. In addition to fabricating vortex ices through a pinning array of nanoscale holes, the scientists also control the phases and crystallinity of the vortex ices by utilizing pinning effect of the stray field of a spin ice consisting of ferromagnetic islands, which can be conveniently tuned in-situ to different states through an applied in-plane magnetic field. The objective is to open and showcase a new direction by achieving a rarely accessible ground state of a square spin ice with vortices. The experiments promise to yield new physical phenomena that can establish the foundation of hybrid artificial ice systems. Graduate students will carry out the experimental work. Thus, this project contributes directly to the training of the future workforce and to the national competitiveness in the important area of nanotechnology.
