Magnetoelectric memory at room temperature
doi:10.1038/nindia.2013.43 Published online 26 March 2013
Researchers have synthesized a novel, nanosized, crystalline ceramic that is capable of exhibiting ferroelectric and ferromagnetic properties at room temperature1. This material will be useful for designing the next generation of nonvolatile memory devices.
Nanomaterials showing both ferroelectricity and ferromagnetism at room temperature are suitable for fabricating memory devices. Such materials have demonstrated sub-nanosecond switching speeds and ultra-low-power voltage-driven write and non-destructive read operations. However, existing materials fail to display such properties at room temperature.
The researchers fabricated the crystalline ceramic using oxides of lead, zirconium, iron and tantalate. They then used a focused ion beam to cut single-crystal slices from the ceramic. Sophisticated imaging techniques revealed that the single-crystal slices had extremely fine microstructures consisting of domains with curved walls.
The primary domains are 10 nm long and form 100-nm-long bundles, which in turn form domain groups with lengths of the order of micrometers. On exposure to varying magnetic fields at room temperature, the domains underwent dramatic changes in patterns. At a low magnetic field, very fine-scale stripe domains adopted a labyrinthine structure, which clearly suggests that the magnetic field affects the domain configurations across all length scales.
"The effect of a magnetic field on ferroelectric domains is very promising for fabricating high-density and low-power nonvolatile random access memory devices," says Ashok Kumar, a co-author of the study.
The authors of this work are from: Materials Physics & Engineering Division, National Physical Laboratory, New Delhi, India; School of Mathematics & Physics, Queen's University Belfast and Department of Physics, Cavendish Laboratory, Cambridge, UK; Department of Physics and the Institute of Multifunctional Materials, University of Puerto Rico, San Juan, Puerto Rico.
- Evans, D. M. et al. Magnetic switching of ferroelectric domains at room temperature in multiferroic PZTFT. Nat. Comm. (2013) doi:10.1038/ncomms2548