Talk 1: Anti-ferroelectric materials for non-volatile digital data storage

Melvin M. Vopson

Faculty of Science, University of Portsmouth, Portsmouth, UK

Developing new data storage technologies that meet the demand at reduced cost and power consumption, have prompted the acceleration of research into solid-state memories, which are fast replacing magnetic hard discs in consumer electronics and portable devices. In this lecture I present the first experimental demonstration of a novel solid-state memory effect in anti-ferroelectric materials [1-3]. The initial experimental demonstration of the memory effect in anti-ferroelectric ceramics shows, remarkably, that the proposed technology encodes data in both ferroelectric sublattices of an anti-ferroelectric medium. This results in a 4-state non-volatile memory capable of storing two digital bits simultaneously, unlike all other volatile and non-volatile Random Access Memory (RAM) technologies that have 2-memory states and are capable of storing one digital bit per cell. On the basis of the newly discovered memory effect, a new RAM memory chip technology is proposed, which uses anti-ferroelectric capacitors to store digital information in four possible memory states. The non-volatile 4-state anti-ferroelectric random access memory was termed AFRAM by the author [1]. It will be shown that the AFRAM memory cell functions using a similar FRAM architecture with one transistor – one capacitor (1T-1C) per cell, it requires a more complex operation protocol, but it retains all the advantages of FRAM, while doubling the memory capacity in the same volume. The discovery of a 4-state memory effect in anti-ferroelectric materials opens new avenues for research and developments in less known anti-ferroelectric solids.

[1]. M. Vopson, X. Tan, 4-state anti-ferroelectric random access memory, Electron Device Letters (2016).

[2]. M. Vopson, G. Caruntu, X. Tan, Polarization reversal and memory effect in anti-ferroelectric materials, Scripta Mater. 128, 61-64 (2017).

[3]. M. Vopson, X. Tan, Nonequilibrium polarization dynamics in antiferroelectrics, Physical Review B 96 (1), 014104 (2017).

Talk 2: Multiferroic technologies for magnetic data storageDr. Melvin Vospon. Senior Lecturer in Applied Physics at the University of Portsmouth and head of the Applied Materials Laboratory

Melvin M. Vopson

Faculty of Science, University of Portsmouth, Portsmouth, UK

Multiferroic materials are a strong alternative to traditional ferroic ordered materials in multiple applications. In this lecture I examine briefly the key physics of multiferroic materials and their possible applications to multiferroic data storage media [1]. Similar to the traditional magnetic data storage, multiferroic data storage implies storing digital information in magnetic domain states, except that the magnetic thin film medium is in fact a multiferroic thin film composite. It is shown that the correct tuning of the multiferroic coupling can either increase or decrease the effective magneto-crystalline anisotropy of the magnetic grains and this is achieved via the electrically activated magneto-electric effect [2]. Based on this effect, two magnetic data storage protocols are proposed, which could potentially replace Heat Assisted Magnetic Recording (HAMR) technology and offer unprecedented increases in the data storage areal density beyond the super-paramagnetic size limit.

[1] M. Vopson, E. Zemaityte, M. Spreitzer, E. Namvar, Multiferroic composites for magnetic data storage beyond the super-paramagnetic limit, Journal of Applied Physics. 116, 11, 113910 (2014).

[2] M. Vopson, S. Lepadatu, Solving the electrical control of magnetic coercive field paradox, Applied Physics Letters. 105, 12, 122901 (2014).