In this work, we systematically studied the deposition, characterization, and crystal structure m... more In this work, we systematically studied the deposition, characterization, and crystal structure modeling of ScAlN thin film. Measurements of the piezoelectric device’s relevant material properties, such as crystal structure, crystallographic orientation, and piezoelectric response, were performed to characterize the Sc0.29Al0.71N thin film grown using pulsed DC magnetron sputtering. Crystal structure modeling of the ScAlN thin film is proposed and validated, and the structure–property relations are discussed. The investigation results indicated that the sputtered thin film using seed layer technique had a good crystalline quality and a clear grain boundary. In addition, the effective piezoelectric coefficient d33 was up to 12.6 pC/N, and there was no wurtzite-to-rocksalt phase transition under high pressure. These good features demonstrated that the sputtered ScAlN is promising for application in high-coupling piezoelectric devices with high-pressure stability.
Abstract A study of ground state properties of bulk BaTiO 3 perovskite crystal was conducted usin... more Abstract A study of ground state properties of bulk BaTiO 3 perovskite crystal was conducted using first-principles density functional theory with local-density approximation (LDA) and generalized-gradient approximation (GGA), using the projector-augmented wave methods. Two different PAW potentials developed by Jollet–Torrent–Holzwarth (JTH) and Garrity–Bennett–Rabe–Vanderbilt (GBRV) are employed in the calculations. This study emphasize on electronic, structural and response properties of all BaTiO 3 phases using different exchange correlation (XC) functionals and PAW potentials. Lattice parameters, cohesion energy, bulk modulus, Born effective charge, spontaneous polarization and charge densities of all BaTiO 3 phases are calculated. In addition, gamma point phonon frequencies are computed with LDA. Structural and vibrational properties predicted using the two PAW potentials are consistent with experimental and previous theoretical studies for all BaTiO 3 phases. It is observed that calculations with GGA yields structural properties much closer to reported experimental values than LDA. Spontaneous polarization computed using Berry phase approach for the three structures in ferroelectric phase are consistent with other theoretical results, but differ considerably from experimental values. The deviation of lattice parameters computed using different XC functionals directly affects the computed spontaneous polarization. An analysis of phonon mode symmetries and frequencies conformed to experimental findings in the literature.
A caustic vector vortex optical field is experimentally generated and demonstrated by a caustic-b... more A caustic vector vortex optical field is experimentally generated and demonstrated by a caustic-based approach. The desired caustic with arbitrary acceleration trajectories, as well as the structured states of polarization (SoP) and vortex orders located in different positions in the field cross-section, is generated by imposing the corresponding spatial phase function in a vector vortex optical field. Our study reveals that different spin and orbital angular momentum flux distributions (including opposite directions) in different positions in the cross-section of a caustic vector vortex optical field can be dynamically managed during propagation by intentionally choosing the initial polarization and vortex topological charges, as a result of the modulation of the caustic phase. We find that the SoP in the field cross-section rotates during propagation due to the existence of the vortex. The unique structured feature of the caustic vector vortex optical field opens the possibility o...
We study the dynamics of polarization switching in a superlattice consisting of periodic ferroele... more We study the dynamics of polarization switching in a superlattice consisting of periodic ferroelectric and paraelectric layers. The dynamics of switching is examined based on the Landau-Khalatnikov equation of motion. Effect of interface coupling on the transient behaviors of polarization and switching time are examined in detail. The spatial distribution of polarizations at different times in switching is illustrated. Our results reveal that the interface coupling plays an important role in determining the switching dynamics of the superlattices. The minimum field requires for polarization switching decreases with increasing interface coupling strength, and this implies that polarization switching is interface-aided.
Analytical far-field expressions for the transverse electric mode and transverse electric magneti... more Analytical far-field expressions for the transverse electric mode and transverse electric magnetic mode terms, and the energy flux distributions of vortex Airy beams are derived based on the vector angular spectrum of the beam and the stationary phase method. The physical pictures of vortex Airy beams from the vectorial structure are illustrated and the energy flux distributions are demonstrated in far-field. The influences of the beam parameters, especially the exponential factor, on the energy flux distributions of vortex Airy beams and its transverse electric mode and transverse electric magnetic mode terms are discussed. This work provides a new understanding of the propagation behaviors and applications of a vortex Airy beam.
ABSTRACT A thermodynamic model of interface intermixing in ferroelectric superlattices with appro... more ABSTRACT A thermodynamic model of interface intermixing in ferroelectric superlattices with appropriate electrostatic boundary condition is developed. Interface intermixing forms intermixed layers with properties different from its constituent layers. In this work, the polarization reversal in ferroelectric superlattices with “switchable” polarization in intermixed layers is examined. Our results reveal that polarization hysteresis in ferroelectric superlattices is accompanied by hysteresis in internal electric fields. The underlying physical mechanisms which induce the internal electric field dependence of applied electric field are discussed by looking at the polarization and internal field profiles.
In this work, we systematically studied the deposition, characterization, and crystal structure m... more In this work, we systematically studied the deposition, characterization, and crystal structure modeling of ScAlN thin film. Measurements of the piezoelectric device’s relevant material properties, such as crystal structure, crystallographic orientation, and piezoelectric response, were performed to characterize the Sc0.29Al0.71N thin film grown using pulsed DC magnetron sputtering. Crystal structure modeling of the ScAlN thin film is proposed and validated, and the structure–property relations are discussed. The investigation results indicated that the sputtered thin film using seed layer technique had a good crystalline quality and a clear grain boundary. In addition, the effective piezoelectric coefficient d33 was up to 12.6 pC/N, and there was no wurtzite-to-rocksalt phase transition under high pressure. These good features demonstrated that the sputtered ScAlN is promising for application in high-coupling piezoelectric devices with high-pressure stability.
Abstract A study of ground state properties of bulk BaTiO 3 perovskite crystal was conducted usin... more Abstract A study of ground state properties of bulk BaTiO 3 perovskite crystal was conducted using first-principles density functional theory with local-density approximation (LDA) and generalized-gradient approximation (GGA), using the projector-augmented wave methods. Two different PAW potentials developed by Jollet–Torrent–Holzwarth (JTH) and Garrity–Bennett–Rabe–Vanderbilt (GBRV) are employed in the calculations. This study emphasize on electronic, structural and response properties of all BaTiO 3 phases using different exchange correlation (XC) functionals and PAW potentials. Lattice parameters, cohesion energy, bulk modulus, Born effective charge, spontaneous polarization and charge densities of all BaTiO 3 phases are calculated. In addition, gamma point phonon frequencies are computed with LDA. Structural and vibrational properties predicted using the two PAW potentials are consistent with experimental and previous theoretical studies for all BaTiO 3 phases. It is observed that calculations with GGA yields structural properties much closer to reported experimental values than LDA. Spontaneous polarization computed using Berry phase approach for the three structures in ferroelectric phase are consistent with other theoretical results, but differ considerably from experimental values. The deviation of lattice parameters computed using different XC functionals directly affects the computed spontaneous polarization. An analysis of phonon mode symmetries and frequencies conformed to experimental findings in the literature.
A caustic vector vortex optical field is experimentally generated and demonstrated by a caustic-b... more A caustic vector vortex optical field is experimentally generated and demonstrated by a caustic-based approach. The desired caustic with arbitrary acceleration trajectories, as well as the structured states of polarization (SoP) and vortex orders located in different positions in the field cross-section, is generated by imposing the corresponding spatial phase function in a vector vortex optical field. Our study reveals that different spin and orbital angular momentum flux distributions (including opposite directions) in different positions in the cross-section of a caustic vector vortex optical field can be dynamically managed during propagation by intentionally choosing the initial polarization and vortex topological charges, as a result of the modulation of the caustic phase. We find that the SoP in the field cross-section rotates during propagation due to the existence of the vortex. The unique structured feature of the caustic vector vortex optical field opens the possibility o...
We study the dynamics of polarization switching in a superlattice consisting of periodic ferroele... more We study the dynamics of polarization switching in a superlattice consisting of periodic ferroelectric and paraelectric layers. The dynamics of switching is examined based on the Landau-Khalatnikov equation of motion. Effect of interface coupling on the transient behaviors of polarization and switching time are examined in detail. The spatial distribution of polarizations at different times in switching is illustrated. Our results reveal that the interface coupling plays an important role in determining the switching dynamics of the superlattices. The minimum field requires for polarization switching decreases with increasing interface coupling strength, and this implies that polarization switching is interface-aided.
Analytical far-field expressions for the transverse electric mode and transverse electric magneti... more Analytical far-field expressions for the transverse electric mode and transverse electric magnetic mode terms, and the energy flux distributions of vortex Airy beams are derived based on the vector angular spectrum of the beam and the stationary phase method. The physical pictures of vortex Airy beams from the vectorial structure are illustrated and the energy flux distributions are demonstrated in far-field. The influences of the beam parameters, especially the exponential factor, on the energy flux distributions of vortex Airy beams and its transverse electric mode and transverse electric magnetic mode terms are discussed. This work provides a new understanding of the propagation behaviors and applications of a vortex Airy beam.
ABSTRACT A thermodynamic model of interface intermixing in ferroelectric superlattices with appro... more ABSTRACT A thermodynamic model of interface intermixing in ferroelectric superlattices with appropriate electrostatic boundary condition is developed. Interface intermixing forms intermixed layers with properties different from its constituent layers. In this work, the polarization reversal in ferroelectric superlattices with “switchable” polarization in intermixed layers is examined. Our results reveal that polarization hysteresis in ferroelectric superlattices is accompanied by hysteresis in internal electric fields. The underlying physical mechanisms which induce the internal electric field dependence of applied electric field are discussed by looking at the polarization and internal field profiles.
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