Abstract
Intensive investigations have been drawn on nanoscale ferroelectrics for their prospective applications such as developing memory devices. In contrast with the commonly used electrical means to process (i.e., read, write or erase) the information carried by ferroelectric domains, at present, mechanisms of non-electrical processing ferroelectric domains are relatively lacking. Here we make a systematical investigation on the stability of 180° cylindrical domains in ferroelectric nanofilms subjected to macroscopic mechanical loads, and explore the possibility of mechanical erasing. Effects of domain size, film thickness, temperature and different mechanical loads, including uniform strain, cylindrical bending and wavy bending, have been revealed. It is found that the stability of a cylindrical domain depends on its radius, temperature and film thickness. More importantly, mechanical loads have great controllability on the stability of cylindrical domains, with the critical radius nonlinearly sensitive to both strain and strain gradient. This indicates that erasing cylindrical domain can be achieved by changing the strain state of nanofilm. Based on the calculated phase diagrams, we successfully simulate several mechanical erasing processes on 4 × 4 bits memory devices. Our study sheds light on prospective device applications of ferroelectrics involving mechanical loads, such as flexible memory devices and other micro-electromechanical systems.
Highlights
Effect of Mechanical Loads on Stability of Nanodomains in Ferroelectric Ultrathin Films: Towards Flexible Erasing of the Non-Volatile Memories
Compared with semiconductors and magnetic materials that are predominately used in current storage technology, ferroelectrics are more attractive in developing memory devices, for their high-density storage capacity and the nonvolatility to retain information without power[3]
In this letter, based on systematical phase field simulations, we demonstrate that stability of polar domains in ferroelectric ultrathin films can be effectively controlled by macroscopic mechanical loads
Summary
Effect of Mechanical Loads on Stability of Nanodomains in Ferroelectric Ultrathin Films: Towards Flexible Erasing of the Non-Volatile Memories. Mechanical loads have great controllability on the stability of cylindrical domains, with the critical radius nonlinearly sensitive to both strain and strain gradient This indicates that erasing cylindrical domain can be achieved by changing the strain state of nanofilm. F erroelectrics are natural candidates for data storage, as they possess switchable spontaneous polarization to carry bit information ‘‘0’’ and ‘‘1’’ Their usefulness originates from a wide spectrum of other important properties, such as piezoelectricity, pyroelectricity, photovoltaic effect, and nonlinear optic behaviors[1,2]. It has been realized that strain gradient can affect polarization in a similar way of electric field, namely flexoelectricity (see reviewed paper Ref. 25) These electromechanical effects provide the possibility of processing ferroelectric domains mechanically. Considering the possible problems of electrical means (e.g., leakage, heat, dielectric breakdown and fatigue), and potential applications of ferroelectrics in non-electrical environments, effective strategies for processing ferroelectric domains by mechanical means would be meaningful
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