The Modulation Of Pulsed High Magnetic Field On Metastable Magnetic Phases And Their Transitions Of DyM?M=Cu,Ag? And CuFe_1-xGa_xO₂

Orthogonal structures of intermetallic compounds and delafossite have complex magnetic interactions due to the presence of transition metals and rare earth metals,and exhibit a variety of magnetic metastable and magnetic transition behaviors under the high magnetic field,presenting magnetism multiferroic behaviors such as magnetostriction,magnetoelectric coupling and magnetocapacitance,which have attracted extensive interest.The intermetallic compound DyM formed by the rare-earth metal Dy has huge magnetoelasticity effect,in which the existence of coupling between electron spin,orbital and lattice couplings and the large quadrupolar interactions lead to the quadrupole phase transitions,various metastable magnetic phases and complicated magnetic transition behaviors.The delafossite CuFeO₂ with triangular structure has typical geometrical frustrated structure,revealing complex magnetic interactions and magnetoelectric coupling,even quantum magnetization behavior has been observed in low temperature.And the doped nonmagnetic Ga³⁺ion has an important effect on the spin-frustation,exchange interaction and metastable magnetic phases,which leads to the complicated behaviors on the magnetization and magnetoelectric coupling.In this paper,the modulations of pulsed high magnetic field in metastable magnetic phase transitions of DyCu,DyAg and CuFe_1-x-x Ga_x O₂ are studied.The research results are as follows:1.The magnetic properties of DyCu and DyAg intermetallic compounds were studied by the usage of pulsed high magnetic field.The study reveals that pulsed high magnetic field can induce a series of metastable magnetic phases and observe the different phase transition characteristics among diverse metastable states.The detailed magnetic phase diagrams of these two intermetallic compounds were obtained according to the magnetization measurements under low and pulsed high magnetic field at different temperatures.In addition,the magnetostrictive measurement showed that the field-induced spin reorientation leads to the change of magnetic structure,and meanwhile,the lattice volume.2.The magnetic anomaly behavior of DyCu was studied.The valence state of Cu was analyzed by XPS measurement of DyCu sample.According to these above,an antiferromagnetic nested structure model had been proposedto explain the magnetic anomaly behavior behavior reasonably.The electron spin resonance and complex impedance properties of DyCu and DyAg intermetallic compounds were studied to further analyze this abnormal magnetization behavior.The results demonstrated that the resonance modes and dipole-like behaviors of these two compounds are significantly different,which verified the rationality of antiferromagnetic nested structure model.3.The magnetic properties of CuFe_1-xGa_xO₂ single crystals with various nonmagnetic Ga³⁺doping levels were measured in a widen magnetic field region to obtain their particular magnetic phase diagram.The observed experiment results indicated that the doped nonmagnetic Ga³⁺ions change partial spin frustration and magnetic coupling at low temperature,and meanwhile,gradually destroy antiferromagnetic spin order of Fe³⁺ions,which results in the dramatic changes of field-induced metastable states and magnetic phases.The effect of doping of nonmagnetic Ga³⁺ions on magnetoelectric coupling of CuFeO₂ was studied.Experimental results indicated that the doped nonmagnetic Ga³⁺ions play a significant role in dielectric polarization behaviors.The dramatically enhanced spontaneous polarizations had been observed in the appropriate doping amount,which means that dopant of Ga³⁺ions have vital modulation effect on magnetoelectric coupling.To conclude,pulsed high magnetic field is the significant extreme experimental condition investigating the metastable states and phase transition in the system of complex magnetic phase interactions.In this study,high magnetic field is capable of inducing the metastable phase transition,destroying?partially destroying?strong antiferromagnetic coupling and geometrical?spin?frustration,which is beneficial for further understanding the abundant magnetic phenomena in these systems with complex magnetic interactions.