Quantum Materials
Quantum materials include materials where electronic or magnetic properties originate from nontrivial quantum mechanics. They are significant to the second quantum evolution that is related to future technologies, like quantum computers and quantum networks. The Gui lab is mainly working on design and synthesis of NEW quantum materials, such as superconductors, magnetic topological materials, quantum spin liquids etc., starting from chemical perspectives (crystal structure, chemical bonding etc.). Moreover, connecting these new quantum materials with real-life applications (quantum computers, memory chips, heterogeneous catalysis etc.) is another major direction of our research. We utilize a variety of experimental techniques, such as solid-state synthesis, crystal growth, powder/single crystal X-ray diffraction, powder/single crystal neutron diffraction, magnetic properties/electrical transport/heat capacity measurements etc. together with density-functional theory (DFT) calculations to achieve our research goals. Meanwhile, we aim to translate the physics of quantum materials into chemical language and bridge solid-state chemistry with other related fields.
Our research is strongly interdisciplinary between chemistry, physics, materials science and electrical engineering. Anyone who is interested in making novel quantum materials and applying them into our life is welcomed to join the group.
New Superconductors and Their Applications to Future Quantum Computers
Superconductors produce zero electrical resistance and magnetic flux expulsion. Various alloys, intermetallics and oxides were found to be superconducting since the first discovery of superconductivity in Hg over a century ago. Regardless of differences in their formulas, a prominent similarity of them is their layered crystal structures. On the other hand, superconducting qubits for quantum computers have become the leading candidate for scalable quantum computers due to its high designability and scalability, and high feasibility to couple and control. Current superconducting materials used for qubits are simple elemental superconductors, such as Al and Nb. Recently, it was found that by replacing superconducting Nb into Ta in superconducting transmon qubits, which is one of the leading platforms for quantum computing, the lifetime, a time that quantum states persist, dramatically increases. Therefore, it is promising that novel superconductors with appropriate properties can pave the way for better multi-qubit processors.
New Material Systems for Quantum Spin Liquid Candidates
In solid-state materials, crystal structures are always relevant to their physical properties that can provide possibilities for real-life applications. Magnetic materials with magnetic atoms in one-dimensional (1-D) or two-dimensional (2-D) sublattices are of great interests to date. With 1-D or special 2-D lattices, i.e., linear chain, honeycomb, triangular and Kagome lattices, materials can exhibit frustrated magnetism which can potentially host quantum spin liquid state, a type of special quantum state that can never be magnetically ordered and has potential to be applied to quantum communication. Besides, some three-dimensional (3-D) lattices hold the same potential as its 1-D and 2-D counterparts in terms of hosting quantum spin liquid state, i.e., pyrochlore lattice. These special structural motifs bring infinite opportunities for us to design/synthesize novel frustrated magnets/quantum spin liquids.
New Magnetic Topological Materials for Spintronic Devices
Topological materials are those where the properties on the surface are different than in the bulk. Because of the special properties, they can be extensively applied, such spintronic devices. Spintronic devices can store/process information by manipulating spins and electrons. Traditionally, they are based on ferromagnetic (FM) semiconductors. In the recent decade, people found that instead of looking for good ferromagnetic semiconductors, which is a hard task so far, antiferromagnetic (AFM) materials can be another great choice. Because for spintronic devices, bandgap is not a necessary part for AFM materials, i.e., AFM spintronic materials can be metals, semimetals, semiconductors and insulators. Moreover, they are even more stable and faster than FM spintronic materials. On the other hand, another new emerging direction is spin-orbit torque on topological semimetals due to the fact that its Dirac quasiparticles observed at Fermi energy can lead to highly efficient spintronic devices. Thus, looking for novel AFM topological semimetals for future spintronic devices are of great interests and this is a field where solid-state chemists can contribute to.
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