First Principle Study Of The Optical&Magnetic Properties Of Two-dimensional Materials

Two-dimensional materials have an atomic thickness,making the quantum confinement effect very obvious,and in turn,gives birth to many novel properties that are completely different from the corresponding bulk materials.At the same time,the members of two-dimensional materials are expanding with continuous research efforts.The wide variety of two-dimensional materials,diverse characteristics,and excellent stackability provide unlimited possibilities for realizing various applications in different fields.This dissertation mainly focused on investigating the optical and magnetic properties of two-dimensional materials at relative larger scale and finite temperature by combining first principles and classical theories.In the first chapter,the development history of two-dimensional materials was first reviewed.Some progress in the research of optical properties and magnetic properties of two-dimensional materials was also summarized.Then the basic theory of the first principle materials calculation and the basic theory of micromagnetic simulation were briefly introduced.In the end,some common magnetoelectric transport test methods in the research of two-dimensional materials were introduced.The second chapter introduces the research work on MoS2 grating using the first principle calculations and Helmholtz-Kirchhoff diffraction theorem.Through simulation,it is proved that one can complete the measurement of in-plane biaxial strain with a one-dimensional MoS2 grating,and the measurement accuracy can reach 1‰.The third chapter introduces the research work on simulating the magnetic properties of Co-doped MoS2 using first-principle calculations and the polaron model.Through the first-principle calculations,the exchange constants needed in the polaron model were obtained.Then,the relationship between the thermodynamic average cosine value of the spin angle between the polarons and the temperature,which indicates the magnetism of Co-doped MoS2 was calculated.Further experimental results were consistent with the simulation,proving the fidelity of our simulations.The fourth chapter introduces the research work on the magnetic dynamics of monolayer MnPS3 using first-principle calculations and micromagnetic simulation methods.Through the M-H and M-T curves obtained by simulation,we have obtained magnetic parameters consistent with the experimental ones.Through further simulation,the antiferromagnetic resonance spectrum and propagating spin-wave dispersion relationship of single-layer MnPS3 were obtained.The fifth chapter introduces the cryo-temperature magnetoelectric transport test system designed and built for our future experimental research on the magnetoelectric transport properties of two-dimensional materials.In this part,we introduced in detail the entire process of equipment selection,equipment integration,and test program writing.Some actual test results completed on this system were also shown.In the sixth chapter,we conclude this dissertation and gave some outlooks on the future research directions.