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Yaojin Wang

Publications and source records attributed to Yaojin Wang.

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Domain size and charge defects on the polarization switching of antiferroelectric domains

The switching behavior of antiferroelectric domain structures under the applied electric field is not fully understood. In this work, by using the phase field simulation, we have studied the polarization switching property of antiferroelectric domains. Our results indicate that the ferroelectric domains nucleate preferably at the boundaries of the antiferroelectric domains, and antiferroelectrics with larger initial domain sizes possess a higher coercive electric field as demonstrated by hysteresis loops. Moreover, we introduced charge defects into the sample and numerically investigated their influence. It is also shown that charge defects can induce local ferroelectric domains, which could suppress the saturation polarization and narrow the enclosed area of the hysteresis loop. Our results give insights into understanding antiferroelectric phase transformation and optimizing the energy storage property in experiments.

cond-mat.mtrl-sci

Crafting the strain state in epitaxial thin films: A case study of CoFe2O4 films on Pb(Mg,Nb)O3-PbTiO3

The strain dependence of electric and magnetic properties has been widely investigated, both from a fundamental science perspective and an applications point of view. Electromechanical coupling through field-induced polarization rotation (PRO) and polarization reorientation (PRE) in piezoelectric single crystals can provide an effective strain in film/substrate epitaxial heterostructures. However, the specific pathway of PRO and PRE is a complex thermodynamic process, depending on chemical composition, temperature, electric field and mechanical load. Here, systematic studies of the temperature-dependent field-induced phase transitions in Pb(Mg,Nb)O3-PbTiO3 single crystals with different initial phase and orientation configurations have been performed. Different types of strains, volatile/nonvolatile and biaxial/uniaxial, have been measured by both macroscopic and in-situ X-ray diffraction techniques. In addition, the strain state of epitaxial Mn-doped CoFe2O4 thin films was examined by magnetic anisotropy measurements, where a giant magnetoelectric coupling has been demonstrated.

cond-mat.mtrl-sci