Abstract
The morphotropic phase boundary (MPB), separating two ferroic phases with rhombohedral and tetragonal crystal symmetries, has been utilized extensively in ferroelectrics because it can lead to high-performance piezoelectricity. Recently, a parallel ferromagnetic MPB was experimentally reported and was suggested that the optimal point for magneto-mechanical applications might lies on the rhombohedral side. However, the insight of the domain structures and switching mechanism near ferromagnetic MPB is still unclear. In this work, phase-field micromagnetic microelastic modeling was employed to simulate the domain formation and magnetization switching of (Tb0.27Dy0.73)Fe2, whose composition is around the rhombohedral side of ferromagnetic MPB. The results show that four kinds of domains of the rhombohedral phase automatically form twins of {110} or {100} boundaries with 71° and 109° domain walls after a process of nucleation and growth. The rhombohedral domain evolution and phase volume fraction under the external field of 120 kA/m along different directions are investigated. In ferromagnetics subject to an alternating magnetic field, domain magnetization switches to cause a magnetization hysteresis loop and an associated butterfly magnetostriction loop with the alternating magnetic field.
Highlights
Electromechanical performance of ferroelectric materials with a composition close to the morphotropic phase boundary (MPB), such as PZT (PbZrO3-PbTiO3),1 PMN-PT (PbMg1/3Nb2/3O3PbTiO3)2 [2], and BZT-BCT (Ba(Zr0.2Ti0.8)O3-(Ba0.7Ca0.3)O3),3 are significantly enhanced
Giant magnetostrictive materials usually exhibit rather complicated domain structures resulted from competing energetic contributions
O domain acting as an intermediate phase provided a lowenergy pathway in R3- and R1+ domain evolution process in the later stage
Summary
Electromechanical performance of ferroelectric materials with a composition close to the morphotropic phase boundary (MPB), such as PZT (PbZrO3-PbTiO3), PMN-PT (PbMg1/3Nb2/3O3PbTiO3)2 [2], and BZT-BCT (Ba(Zr0.2Ti0.8)O3-(Ba0.7Ca0.3)O3), are significantly enhanced. More and more attention had been paid to the ferromagnetic materials with a composition near the MPB for the maximum magneto-mechanical properties. Based on the physical parallel of MPB in ferroic materials, the phase transition and domain structure of giant magnetostrictive materials have been experimentally investigated by several researchers. Ma et al found a nanodomain microstructure with the coexistence of R and tetragonal (T) phases in the vicinity of the MPB region.10 Despite such extensive experimental studies in ferromagnetic MPB, the insight of the domain structures and switching near ferromagnetic MPB is still lacking. Our previous work demonstrated that the phase-field method could explain well the multi-domain structures near ferromagnetic MPB. The phase-field micromagnetic microelastic modeling is employed to simulate the domain formation and magnetization switching of (Tb0.27Dy0.73)Fe2, whose composition is at the rhombohedral side of ferromagnetic MPB The rhombohedral (R) distortion might contribute to the giant magnetostrictive response. In this work, the phase-field micromagnetic microelastic modeling is employed to simulate the domain formation and magnetization switching of (Tb0.27Dy0.73)Fe2, whose composition is at the rhombohedral side of ferromagnetic MPB
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