TITLE: Experimental Magnetic Imaging Study of Novel States in Artificial Spin Ice Systems
ABSTRACT: Artificial spin ice systems are two dimensional arrays of magnetic nanoislands that are designed to study the collective behavior of frustrated systems. Each nanoisland possesses a discrete magnetic moment and the interactions between moments can be controlled by modifying the nanoislands’ shape, lateral dimensions, and geometrical arrangement. This thesis focuses on the novel states of different artificial spin ice systems and experimental studies of the magnetic configurations in those states using a variety of imaging techniques. We optimized the annealing protocol for accessing the collective artificial spin ice ground states, using the square ice lattice. The annealing study was then extended to examine the ground state of Santa Fe Ice, whose magnetic configuration can be described under an emergent string framework. We also measured the thermally active Santa Fe Ice system and analyzed the dynamics through string kinetics. Finally, we utilized the annealing protocol to study the low energy state of the triangular tripole ice lattice, in which each nano-island has three equilateral arms and six degrees of freedom in its moment. All these studies demonstrate the existence of novel states and complex cooperative emergent behavior in artificial spin ice systems.