MRI: Development of a system for low temperature optical measurement of 3D magnon, plasmon and spin torque transfer dynamics.

Over the past 15 years scientists and engineers have realized that integrating logic and information storage functions could dramatically improve the energy efficiency of computing devices and enable new and more powerful computing paradigms. Promising materials for creating such a device include those materials in which electrical current strongly interacts with the spin of electrons. The spin of an electron can be thought of as a tiny bar magnet attached to the electron in which the north pole of the magnet can be oriented up, down, or in any other direction. To develop new computing platforms that integrate charge and spin functionality, it is necessary to study how these spins change direction in response to external stimuli such as electrical current or pulses of light. These changes occur very quickly in about one billionth of one second. This award supports the development of an instrument to study spin reorientation by measuring the spin direction with extremely short pulses of light that arrive at the sample at precisely controlled times relative to external stimuli such as an electrical current or a beam of light. Measurements will be carried out at very low temperatures to isolate and understand the fundamental physical processes. This knowledge will provide the scientific foundation for engineering appropriate materials for application in future computing devices. The work is being coordinated with a new graduate-level course on the materials under investigation and support the training of one postdoctoral researcher and two undergraduate researchers.

Spin-based phenomena in topological insulators and magnetic heterostructures have attracted a great deal of attention from the perspective of both fundamental science and device development. However, the underlying physical origin of many of these phenomena remains vague. Moreover, the dynamics of these phenomena, which are critical for device applications, remain poorly understood. This award supports the development of an instrument that will enable ultrafast optical measurements of collective magnetic and charge excitations and spin transfer dynamics at low temperatures and in three-dimensional magnetic fields. The new instrument will allow scientists to answer fundamental scientific questions about quantum materials, magnetic heterostructures, and other 'quantum engineered' heterogeneous materials and identify routes to tailor these heterogeneous materials for spintronic, optoelectronic, and quantum device applications. The new instrument will enable the first ultrafast measurements of the dynamics of spin transfer torque. The three dimensional resolution and integrated optical, magnetic, and electrical control will allow scientists to separate, understand, and ultimately control competing processes. The instrument will also provide unprecedented measurement of magnon and plasmon dynamics in topological insulators and heterogeneous materials designed to control the emergence of interfacial phenomena with unique quantum mechanical properties. Successful development of the instrument will enable new interactions between fundamental science, applied science, and device engineering fields. It will enable the breakthroughs required for widespread adoption of 'exotic' materials in device technologies. Conceptual aspects of the research enabled by this instrument will be integrated into new graduate and undergraduate courses and science education outreach programs. Members of underrepresented groups will be actively recruited for both the postdoctoral and undergraduate researcher positions supported by the award.