Project Name:
Novel Quantum Physical Properties Caused by Strong Spin-orbit Coupling and Multi-Field Regulation under Integrated Extreme Conditions
Project leader:
Xu Gang
Reporting unit:
Huazhong University of Science and Technology
Project funding:
4.47 million yuan
Project period:
2018.5.1-2023.4.30
Project Description:
The exploration and application of new physical materials and new materials have played an important role in promoting scientific and technological progress and social development. Strong spin-orbit coupling (SOC), as a new form of electronic association, can lead to many novel physical phenomena. It is a frontier research field that is important in both basic physics and technology applications, and can meet future electronic devices. Low cost, fast response, and large-scale regulation. In view of its important scientific significance and application value, this project will combine the pre-work accumulation and its own advantages, relying on the pulsed magnetic field science device, and have strong SOC correlation around topological semi-metal, topological superconductor, Ising superconductor and multi-pole moment materials. The electronic system is deeply studied from the theoretical calculation of materials, sample growth, physical property characterization and comprehensive extreme conditions and multi-field regulation under strong magnetic fields. The specific project objectives, research content and research methods are summarized as follows:
1. Use the first-principles calculation to study the electronic structure and topological properties of 4d and 5d transition metal compounds, and 3-4 new topological semi-metals with stable structure and excellent properties will designed and found. The high-quality single crystal of two or more kinds of solid-phase reactions will be synthesized. The electronic structure and physical properties will be characterized by angle-resolved photoelectron spectroscopy (ARPES), scanning electron microscopy (STM) and electromagnetic transport under strong magnetic field, and its topological properties will be examined; The modulation of electronic structure and topological properties such as stress, dimension and substrate proximity effect will be studied; use strong magnetic field to induce topological phase transitions, search new topological quantum states.
2. At least one topological superconducting system will be successfully prepared experimentally. Focus on two-dimensional transition metal chalcogenides and iron-based superconductors with reversed-electron structures. Studied the electronic properties, band structure, symmetry and pairing mechanism of superconducting energy gaps, experimentally observe the Majorana zero-energy modes, reveal the intrinsic mechanism of constructing topological superconducting states. Explore the key factors affecting the superconductivity and topological properties of materials, and construct electronic phase diagrams of different ordered quantum states such as superconductivity, topology and magnetism. Develop an experimental method to effectively control topological superconductivity.
3. Study the spin polarization and vortex dynamics of the Ising superconductor; determine the upper critical magnetic field and the magnetic field induced BKT phase transition; improve the temperature-magnetic field-carrier concentration phase diagram of the Ising superconductor to determine the respective magnetic fields, study the physical properties of the region; modulate the Ising superconductivity through the ionic liquid method, improve the superconducting transition temperature, realize the multi-field regulation of Ising superconductivity, enrich its phase diagram and deepen the understanding of the Ising superconducting mechanism.
4. Theoretically, derive the microscopic forms of all 36 order parameters including cubic lattice transition t, strong correlation effect U and spin-orbit coupling λ under cubic symmetry by the non-regressive phase approximation (RPA) and the Landau-Ginsberg method; give its phenomenological theory. Experimentally, use strong magnetic field transport, resonance X-ray scattering (RXS), second harmonic conversion, etc. to detect and confirm Ru (RuCl3), Re (Cd2Re2O7), Os (LiOsO3), Ir ( Y2Ir2O7) multipole moment sequence parameters in strong spin-orbit coupling compounds; determine phase transition temperature and order parameter symmetry, and manipulate quantum phase transition between different order parameters by multi-field regulation such as strong magnetic field, light field and high voltage; explore new quantum state; complete the construction of the first domestic transmission and magnetic measurement platform under the extreme conditions of strong magnetic field (60T), low temperature (1.5K) and high pressure (4Gpa) during the project promotion process, and open to the outside world in the future .
These four aspects are the most cutting-edge research directions in the field of quantum regulation, which are related to each other and complement each other. For example, topological semimetals may also become topological superconductors by proximity effect or carrier doping; two-dimensional transition metal chalcogenide is both a high-quality candidate for Ising superconductors and an interface topology superconducting system; The study of order parameters also plays an important role in modulating new topological states and superconductivity.
