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A diode for ferroelectric domain-wall motion.

Whyte JR, Gregg JM - Nat Commun (2015)

Bottom Line: Revolutionary technologies have resulted, like racetrack memory and domain-wall logic.Until recently, equivalent research in analogous ferroic materials did not seem important.Domain walls can move readily in the direction in which thickness increases gradually, but are prevented from moving in the other direction by the sudden thickness increase at the sawtooth edge.

View Article: PubMed Central - PubMed

Affiliation: Centre for Nanostructured Media, School of Maths and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, UK.

ABSTRACT
For over a decade, controlling domain-wall injection, motion and annihilation along nanowires has been the preserve of the nanomagnetics research community. Revolutionary technologies have resulted, like racetrack memory and domain-wall logic. Until recently, equivalent research in analogous ferroic materials did not seem important. However, with the discovery of sheet conduction, the control of domain walls in ferroelectrics has become vital for the future of what has been termed 'domain-wall electronics'. Here we report the creation of a ferroelectric domain-wall diode, which allows a single direction of motion for all domain walls, irrespective of their polarity, under a series of alternating electric field pulses. The diode's sawtooth morphology is central to its function. Domain walls can move readily in the direction in which thickness increases gradually, but are prevented from moving in the other direction by the sudden thickness increase at the sawtooth edge.

No MeSH data available.


The working principle of a ferroelectric shift register.Under conventional circumstances, applied field pulses cause domain walls of opposite polarity to move in opposite directions, as domains in which polarization is favorably aligned with the applied field expand, while others contract (a). However, if the potential landscape can be designed as a series of saw-teeth, then, for a range of applied field magnitudes, domain walls of one polarity are frozen into position while those of opposite polarity move (b). If successive alternating field pulses are used of the right magnitude and duration, then domain walls of different polarity can move alternately all in the same direction and a domain-wall shift register based on ratchet-like domain-wall motion can be realized (c). The key building block is the diode responsible for the repeating unit in the sawtooth potential.
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f1: The working principle of a ferroelectric shift register.Under conventional circumstances, applied field pulses cause domain walls of opposite polarity to move in opposite directions, as domains in which polarization is favorably aligned with the applied field expand, while others contract (a). However, if the potential landscape can be designed as a series of saw-teeth, then, for a range of applied field magnitudes, domain walls of one polarity are frozen into position while those of opposite polarity move (b). If successive alternating field pulses are used of the right magnitude and duration, then domain walls of different polarity can move alternately all in the same direction and a domain-wall shift register based on ratchet-like domain-wall motion can be realized (c). The key building block is the diode responsible for the repeating unit in the sawtooth potential.

Mentions: The key to developing a shift register is to find a way to move all domain walls in the same direction. This is not trivial. If a conventional field were applied to a set of domains under normal circumstances, those with dipoles oriented favourably with respect to the field would grow, while others would contract, such that domain walls of opposite polarity (defined by the specific sequence of adjacent domain orientations) would move in opposite directions (Fig. 1a). In Cowburn's domain-wall logic circuits212223, a shift register was achieved by using a combination of carefully crafted wire geometries and a rotating H-field; in Parkin's racetrack memory24, it was achieved by passing a spin-polarized current along the nanowire such that the spin-torque momentum transferred to the domain walls, as a result of spin reorientation between domains, generated a common sense of domain-wall movement parallel to the net electron flow. Neither of these strategies can be readily adapted to generate ferroelectric shift registers: the discrete polarization directions in a ferroelectric unit cell mean that rotating electric fields would not lead to the same domain-wall dynamics as in nanomagnetics, and the physics associated with spin-polarized charge transport is not relevant to ferroelectrics.


A diode for ferroelectric domain-wall motion.

Whyte JR, Gregg JM - Nat Commun (2015)

The working principle of a ferroelectric shift register.Under conventional circumstances, applied field pulses cause domain walls of opposite polarity to move in opposite directions, as domains in which polarization is favorably aligned with the applied field expand, while others contract (a). However, if the potential landscape can be designed as a series of saw-teeth, then, for a range of applied field magnitudes, domain walls of one polarity are frozen into position while those of opposite polarity move (b). If successive alternating field pulses are used of the right magnitude and duration, then domain walls of different polarity can move alternately all in the same direction and a domain-wall shift register based on ratchet-like domain-wall motion can be realized (c). The key building block is the diode responsible for the repeating unit in the sawtooth potential.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490414&req=5

f1: The working principle of a ferroelectric shift register.Under conventional circumstances, applied field pulses cause domain walls of opposite polarity to move in opposite directions, as domains in which polarization is favorably aligned with the applied field expand, while others contract (a). However, if the potential landscape can be designed as a series of saw-teeth, then, for a range of applied field magnitudes, domain walls of one polarity are frozen into position while those of opposite polarity move (b). If successive alternating field pulses are used of the right magnitude and duration, then domain walls of different polarity can move alternately all in the same direction and a domain-wall shift register based on ratchet-like domain-wall motion can be realized (c). The key building block is the diode responsible for the repeating unit in the sawtooth potential.
Mentions: The key to developing a shift register is to find a way to move all domain walls in the same direction. This is not trivial. If a conventional field were applied to a set of domains under normal circumstances, those with dipoles oriented favourably with respect to the field would grow, while others would contract, such that domain walls of opposite polarity (defined by the specific sequence of adjacent domain orientations) would move in opposite directions (Fig. 1a). In Cowburn's domain-wall logic circuits212223, a shift register was achieved by using a combination of carefully crafted wire geometries and a rotating H-field; in Parkin's racetrack memory24, it was achieved by passing a spin-polarized current along the nanowire such that the spin-torque momentum transferred to the domain walls, as a result of spin reorientation between domains, generated a common sense of domain-wall movement parallel to the net electron flow. Neither of these strategies can be readily adapted to generate ferroelectric shift registers: the discrete polarization directions in a ferroelectric unit cell mean that rotating electric fields would not lead to the same domain-wall dynamics as in nanomagnetics, and the physics associated with spin-polarized charge transport is not relevant to ferroelectrics.

Bottom Line: Revolutionary technologies have resulted, like racetrack memory and domain-wall logic.Until recently, equivalent research in analogous ferroic materials did not seem important.Domain walls can move readily in the direction in which thickness increases gradually, but are prevented from moving in the other direction by the sudden thickness increase at the sawtooth edge.

View Article: PubMed Central - PubMed

Affiliation: Centre for Nanostructured Media, School of Maths and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, UK.

ABSTRACT
For over a decade, controlling domain-wall injection, motion and annihilation along nanowires has been the preserve of the nanomagnetics research community. Revolutionary technologies have resulted, like racetrack memory and domain-wall logic. Until recently, equivalent research in analogous ferroic materials did not seem important. However, with the discovery of sheet conduction, the control of domain walls in ferroelectrics has become vital for the future of what has been termed 'domain-wall electronics'. Here we report the creation of a ferroelectric domain-wall diode, which allows a single direction of motion for all domain walls, irrespective of their polarity, under a series of alternating electric field pulses. The diode's sawtooth morphology is central to its function. Domain walls can move readily in the direction in which thickness increases gradually, but are prevented from moving in the other direction by the sudden thickness increase at the sawtooth edge.

No MeSH data available.