CAREER: Coherent Phonon Control in Iron-Based Superconductors

Trustees Of Boston University, Boston

Investigators

Abstract

Nontechnical Abstract: High-temperature superconductivity is a remarkable phenomenon found in quantum materials. To understand and control superconductivity is the key to next-generation devices to handle information or harvest energy. The physical properties of high-temperature superconductors are extremely sensitive to their crystal structures. Tailored laser pulses can selectively control structural features which are crucial for materials properties. In certain cases, laser excitation can create crystal structures hosting novel functionalities which are impossible to achieve by other methods. This research uses tailored laser pulses to optically engineer the structure of iron-based superconductors. The goal is to advance our knowledge on the relation between crystal structure and high-temperature superconductivity, and to identify the most efficient knob to control superconductivity. This project also includes broad education and outreach programs for female graduate students in physics, local female high school students, and K-12 students. These activities aim at inspiring excitement about experimental physics, and helping students to recognize opportunities for future education and academic careers in materials science. Technical Abstract: Controlling the physical properties of quantum materials along non-invasive and ultrafast pathways is the key for developing next-generation devices. Small structural perturbations created by laser excitation of phonons can directly and selectively modify structural parameters which are crucial to the physical properties of quantum materials. This project aims at optically investigate and manipulate superconductivity and competing orders in iron-based superconductors by modulating the iron-arsenic/selenium distance. The project uses long-wavelength laser excitation directly targets lattice modes which control the iron-arsenic/selenium distance to realize novel phases which do not exist at equilibrium. A desirable outcome of this approach is stabilizing transient superconductivity at high temperatures. This research will advance our knowledge on the relevant degrees of freedom that can be tuned, and novel and exotic phases which can be generated by coherent terahertz fields. The methods used for iron-based superconductors can be applied to a broad category of materials including cuprates, ferroelectrics and multiferroics to identify the most efficient knob to steer quantum materials to desired phases. The research also has industry impacts on the development of next-generation optoelectronic devices, such as superconducting devices which can be optically engineered using coherent terahertz radiation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.