This award supports research in condensed matter physics and materials theory that focuses on understanding the coupling between spin and other internal degrees of freedom and environmental factors in spin-orbit coupled molecular nanostructures. Both quantum-mechanical computer simulations based on first-principles computations and model Hamiltonian approaches will be employed to achieve this goal. Spin degrees of freedom in nanostructures provide both complexity and control knobs of properties of nanostructures. They can be coupled to other internal degrees of freedom, and are very susceptible to external perturbations such as temperature, pressure, mechanical stretching, current, or magnetic field, at the nanometer scale. This coupling and response to perturbations can be used to manipulate properties of nanostructures for effective, efficient nanoscale devices.
To study physical properties of nanostructures, it is customary to rely on either large-scale computer simulations or theoretical models. However, the coupling and response to perturbations in nanostructures turn out to be so subtle that either quantum-mechanical simulations or a model Hamiltonian approach with arbitrary parameter values alone cannot provide a comprehensive picture of the coupling and its consequences in properties of nanostructures. The specific objectives of the research to be carried out are as follows:
(1) To clarify coupling mechanisms and to quantify the strengths of coupling of spin to other degrees of freedom and external environmental factors such as substrate and current, using quantum-mechanical simulations (density-functional theory including spin-orbit coupling).
(2) To investigate responses of spin degrees of freedom and its coupling to the environmental factors using a model Hamiltonian approach with parameter values obtained from the quantum-mechanical simulations.
The results of the proposed research will be compared with experiments via international and national collaborations. The outcomes of the research will shed light on new ways to greatly increase spin transfer/transport and spin polarization in molecular nanostructures, and to build energy-saving new spin-based devices.
This award also supports education of undergraduate and graduate students and a postdoctoral researcher by engaging them in research at the forefront of nanoscience and high-performance computing. To integrate the proposed research efforts into education, the PI will incorporate the outcomes of the proposed research into a new 4000-level course, "Nanomaterials and Devices", designed for a new Nanoscience undergraduate degree program in the College of Science.
NON-TECHNICAL SUMMARY
This award supports research in condensed matter physics and materials theory that focuses on understanding the coupling between different quantum-mechanical degrees of freedom and its consequences in molecular nano-structures that are approximately one millionth the size of the human hair. Among those degrees of freedom, the electron "spin" is of particular interest because it provides both complexity and control knobs to manipulate various properties of molecular nano-structures. Spin degrees of freedom can interact with other internal degrees of freedom, and they are very susceptible to environmental factors such as temperature, pressure, mechanical stretching, current, or magnetic field, at the nanometer scale. This coupling and response to environmental factors can be used to manipulate properties of nanostructures to build new energy-saving tiny devices.
To study physical properties of nanostructures, it is customary to rely on either large-scale computer simulations or theoretical models. However, the coupling and response to environmental factors in nanostructures turn out to be so subtle that either computer simulations or mathematical models alone cannot provide a comprehensive picture of the coupling and its consequences in properties of nano-structures. In this research, the PI will use both approaches to achieve the following objectives:
(1) Using large-scale computer simulations, the mechanisms through which spin couples to other degrees of freedom and external environmental factors will be clarified and the relevant coupling strengths will be quantified.
(2) Using mathematical models with parameter values obtained from the simulations, the response of spin degrees of freedom to various environmental factors will be investigated.
The results of the proposed research will be compared with experiments via international and national collaborations. The outcomes of the research will shed light on new ways to greatly increase spin transport in molecular nanostructures, and to build new energy-saving devices at the nanoscale.
This award also supports education of undergraduate and graduate students and a postdoctoral researcher by engaging them in research at the forefront of nanoscience and high-performance computing. To integrate the proposed research efforts into education, the PI will incorporate the outcomes of the proposed research into a new 4000-level course, "Nanomaterials and Devices", designed for a new Nanoscience undergraduate degree program in the College of Science.
