The anticipated end of Moore’s Law scaling necessitates fundamental research that can lead to devices governed by state variables beyond the charge state variables used in the vast majority of current high performance computing devices. Almost all modern memory and logic devices manipulate the electric charge of electrons. However, as devices get smaller to hold more transistors to process and store ever more data, the amount of power needed to operate these devices increases exponentially and will soon outstrip the world’s ability to operate such computers.

Furthermore, physical limitations on size, speed, and endurance of charge-state devices necessitate entirely new paradigms for computing devices that will allow for necessary growth in computing performance. High risk, high reward applied research leading to novel device designs is essential to mitigate technological surprise and advance the mission of the future. Precise control of magnetic ordering as an alternative state variable, where devices are no longer limited to charge manipulation, has the potential to vastly increase memory efficiency, thereby enabling a new paradigm in ultra-low power electronics.

• Previous attempts to employ the low-power control of magnetism by both commercial and academic researchers have focused on piezoelectric strain mediated control of magnetism (The VCMA effect). However, in all of these cases control has been limited to affecting magnetostriction, carrier charge density, ferromagnetic resonance, or magnetocrystalline anisotropy. Although this offers possible advantages for certain types of devices, it does not accomplish the goal of using intrinsic magnetism as a state variable, and will not lead to devices that offer the orders of magnitude improvements necessary to overcome current device limitations.
• Recently, it was shown that certain materials, for example FeRh, can be controllably toggled from an antiferromagnetic state to a ferromagnetic state using external stimuli. This transitionable magnetic material has been termed “metamagnetic.” It was demonstrated that the transition temperature can be precisely controlled using strain, leading to proposals of heterostructure devices of metamagnetic materials on piezoelectric films, whereby the magnetic ordering is controlled by an ultra-low power gate. This is an entirely new and novel device paradigm ideally suited for future high performance computing applications. Creating a logic or memory device that utilizes magnetism as a state variable, such as a metamagnetic device, has the potential for orders of magnitude lower power operation and orders of magnitude higher speed than the state-of-the-art, while offering non-volatility, high endurance, and inherent radiation hardness.
• The NRC Postdoctoral Fellow in this role will identify, fabricate, characterize, and fully understand devices that use magnetism as a state variable through the control and triggering of metamagnetic transitions for future high performance computing electronics and optical applications.

 Example Approaches:

• Research on the fabrication of uniform, device quality metamagnetic materials under three dimensions of quantum confinement
• Research to determine how to precisely control magnetism with external stimuli in a computing device (for example with temperature, ion implantation, electric field, light, disorder, etc.)
• Investigate the physics of these control mechanisms using world class analysis techniques at world class Neutron, Muon and ultra-bright photon source facilities
• Research on fabricating memory and logic devices that utilize magnetism as a state variable
• Research on the nanoscale properties and effects of nanoscale patterning on metamagnetic transitions
• Research to characterize and optimize the performance of novel metamagnetic devices
• Research to identify new metamagnetic materials that are ideally suited to magnetic state variable device integration using theoretical modeling or experimental measurements

 

key words

Metamagnetism; Nanofabrication; FeRh; Neutron Scattering; Polarized Neutron Scattering; Thin Film Growth; Magnetotransport; X-ray differaction; Muon Spin Resonance; Ion Irradiation

Citizenship:  Open to U.S. citizens and permanent residents

Level:  Open to Postdoctoral applicants