First-principles Investigations of Low Dimensional Materials as Condensed Matter Quantum Simulators

Yifan GAO (高一帆)

11751012

博士

物理

理学博士

黄丽

林念

2021-08-19

2021-12-31

香港科技大学

香港

In the past few decades, low dimensional materials have received extensive attention for their remarkable features and promising applications in nanoelectronics, optoelectronics, quantum computing, quantum communication, etc. To investigate the rich physics inside, abundant theo_x0002_retical models were built to explore quantum effects present in low dimensional materials. The development of these theories have been far ahead the experimental realizations. Feymannsuggested that simulating these quantum models in controllable real systems could lead to a better understanding. In this thesis, several real systems, such as metal-organic frameworks and moiré heterostructures, are demonstrated as good quantum simulators beyond ultracold gases of bosonic and fermionic atoms. Based on first-principles calculations, the experimental obser_x0002_vations in such systems are explained based on various quantum models: in the first project, the structural and electronic properties of VI3 are discussed by comparing with the experimen_x0002_tal Raman spectra. The Dirac type magon with nontrivial bosonic topology is further investigated based on Heisenberg spin Hamiltonians. In the second project, an antiferroelastic onedimensional spin crossover chain is demonstrated to behave collective domino-like switching. A simple 1+1 model is further proposed to fit the phase diagram. In the third project, twodimensional metal-organic network Fe-HITP is presented to exhibit a ferromagnetic groundstate with several topological nontrivial gaps opened due to the spin?orbit coupling, signifying quantum anomalous Hall features. This work implies that metal-organic frameworks could provide a versatile simulation platform to mimic topological quantum states. At last, the hourglass fermion protected by screw rotation is predicted in twisted bilayer SnS. These results would broaden the landscape of accessible physics in twisted layered systems to include the broad realm in topologic semimetals and may motivate further topology and valleytronics related researches in moiré heterostructures.

Low dimensional materials quantum simulators first-principles calculations topological materials metal-organic frameworks spin crossover moiré heterostructures

英语

联合培养

南方科技大学

Yifan GAO . First-principles Investigations of Low Dimensional Materials as Condensed Matter Quantum Simulators[D]. 香港. 香港科技大学,2021.