Ferroelectric glass of spheroidal dipoles with impurities: Polar nanoregions, response to applied electric field, and ergodicity breakdown

Abstract

Using molecular dynamics simulation, we study dipolar glass in crystals composed of slightly spheroidal, polar particles and spherical, apolar impurities between metal walls. We present physical pictures of ferroelectric glass, which have been observed in relaxors, mixed crystals (such as KCN${}_x$KBr${}_{1-x}$), and polymers. Our systems undergo a diffuse transition in a wide temperature range, where we visualize polar nanoregions (PNRs) surrounded by impurities. In our simulation, the impurities form clusters and their space distribution is heterogeneous. The polarization fluctuations are enhanced at relatively high $T$ depending on the size of the dipole moment. They then form frozen PNRs as $T$ is further lowered into the nonergodic regime. As a result, the dielectric permittivity exhibits the characteristic features of relaxor ferroelectrics. We also examine nonlinear response to cyclic applied electric field and nonergodic response to cyclic temperature changes (ZFC$/$FC), where the polarization and the strain change collectively and heterogeneously. We also study antiferroelectric glass arising from molecular shape asymmetry. We use an Ewald scheme of calculating the dipolar interaction in applied electric field.

arXiv comment17 pages, 18 figures

References in corpus (11)

• Direct observation of the formation of polar nanoregions in Pb(Mg${}_{1/3}$Nb${}_{2/3}$)O${}_3$ using neutron pair distribution function analysis
• Ideal glass transitions for hard ellipsoids
• Aging in K${}_{1-x}$Li${}_x$Ta0${}_3$: a domain growth interpretation
• Crystal structures and freezing of dipolar fluids
• Interplay between static and dynamic polar correlations in relaxor Pb(Mg_{1/3}Nb_{2/3})O_{3}
• Ferroelectric and Dipolar Glass Phases of Non-Crystalline Systems
• Molecular Dynamics Simulation of Water between Metal Walls under Electric Field: Dielectric Response and Dynamics after Field Reversal
• Applying electric field to charged and polar particles between metallic plates: Extension of the Ewald method
• Fluctuations of local electric field and dipole moments in water between metal walls
• Orientational glass in mixtures of elliptic and circular particles: Structural heterogeneities, rotational dynamics, and rheology
• Molecular dynamics simulation of orientational glass formation in anisotropic particle systems in three dimensions

Cited by in corpus (1)

• Emergent elasticity linked to topological phase transitions controlled via molecular chirality and steric anisotropy