Research On The Physical Properties Of Multiferroic Materials And New Vanadate Materials Based On Condensed Matter Nuclear Magnetic Resonance

In recent years,in the direction of condensed matter physics,the exploration of new materials is no longer the only hot spot.With the improvement of technology,people have turned to the use of more advanced technologies for further exploration of some conventional materials.This article mainly uses the nuclear magnetic resonance technology to measure the ferroelectric transition temperature properties of common copper-based non-oxide multiferroic materials CuBr₂,CuCl₂,and increase its transition temperature by pressurization,so as to find the correlation between the two.A more detailed NMR measurement of the new vanadate compound NaKV₄O₉·2H₂O was also performed to obtain the spin gap.In the first chapter,we first gave a basic introduction to the basic structure and research status of multiferroic materials and vanadate compounds.In the second chapter,we introduce the principles of NMR technology and practical applications of NMR in condensed matter physics and other related experimental methods in the paper.In the third chapter,we carry out the NMR measurement of CuBr₂ at atmospheric pressure and obtain the change of ferroelectric transition temperature under different pressures by pressure,and further verify the use of the dielectric constant method.By measuring,we found that the transition temperature increases with the increase of pressure,and meets a certain fitting formula.In Chapter 4,we further measured the dielectric constant of CuCl₂,another kind of multiferroic material,under different pressures.Through measurement,we also found the same phenomenon,but the increase was different from that of CuBr2,which we believe may be related to the lattice structure of the material.In Chapter 5,we performed a nuclear magnetic resonance measurement of a new vanadate compound,Na KV₄O₉·2H₂O,by fitting and fitting the obtained measured shifts,spin-lattice relaxation rate,and the full width at half maximum of the resonance line.The size of its spin gap was obtained.Through NMR technology,we have found that the ferroelectric transition temperature of multiferroic materials has a certain relationship with the pressure,and the spin gap of NaKV₄O₉·2H₂O is calculated.