A computational study of cyclic thermal response of shape memory alloy thin-film island structures

Abstract

With a view toward contributing to the state of the art in the research on shape memory alloy memory storage devices, the thermal response of a shape memory alloy (SMA) thin film during a complete cycle of heating and cooling is computationally addressed in this communication. The ultimate objective is to provide a better understanding of shape memory alloys within the context of the characteristics of thermally activated phase-transforming materials as candidate materials for memory devices. In this study, the effect of the current density, thickness of the SMA thin film, convection and boundary conditions on the transformation of the SMA thin film are investigated. In particular, we study the effect of pulse heating as that is important for memory devices. A comparison is made between the cyclic response time of a an SMA unit cell and an Ovonic unit memory (OUM) cell. The total cycle time for the SMA cell and the OUM cell is 0.7 and 60 ns, respectively. The total energy consumption per cycle for the SMA cell and the OUM cell is 0.441 and 37.8 pJ, respectively. While the response of the SMA cell is almost two orders of magnitude better than the OUM cell, we want to strike a cautionary note that the results for the SMA cell are computational and those for the OUM cell are experimental in nature. Regardless, we hope that the outcomes for the SMA cell will provide some motivation for research in SMA-based memory devices.