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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 ferroelectric domain-wall diode.Schematic illustration of a KTP lamella with a sawtooth cross-sectional morphology, straddling an interelectrode gap, in a coplanar capacitor device (a). The real device was imaged (b) using SEM (52° tilt); in c, a line profile of the lamellar surface topography along with a plan-view AFM image (inset), with the location at which the line profile was taken marked in red, are presented. The domain-wall injection and motion associated with switching this device are presented in d–f. In each case, the cross-sectional morphology (top) is aligned with the plan-view PFM amplitude (middle) and phase (bottom). The panels in d illustrate the initial fully poled monodomain state after the application of +100 V bias pulse. In e, a partially switched state (after the application of −55 V) is given: a new domain wall has been injected and progressed from right to left up the ramp and over the sawtooth edge. In f, the state after a further bias pulse (+32 V) was applied in the original poling sense is presented: a domain wall of the opposite polarity has been injected into the device and moved to the base of the ramp. Little movement in the original wall injected in e has occurred, due to the potential barrier associated with the steep ledge of the sawtooth structure. The scale bar in b is 5μm long, while those in d–f are 3μm long.
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f3: The ferroelectric domain-wall diode.Schematic illustration of a KTP lamella with a sawtooth cross-sectional morphology, straddling an interelectrode gap, in a coplanar capacitor device (a). The real device was imaged (b) using SEM (52° tilt); in c, a line profile of the lamellar surface topography along with a plan-view AFM image (inset), with the location at which the line profile was taken marked in red, are presented. The domain-wall injection and motion associated with switching this device are presented in d–f. In each case, the cross-sectional morphology (top) is aligned with the plan-view PFM amplitude (middle) and phase (bottom). The panels in d illustrate the initial fully poled monodomain state after the application of +100 V bias pulse. In e, a partially switched state (after the application of −55 V) is given: a new domain wall has been injected and progressed from right to left up the ramp and over the sawtooth edge. In f, the state after a further bias pulse (+32 V) was applied in the original poling sense is presented: a domain wall of the opposite polarity has been injected into the device and moved to the base of the ramp. Little movement in the original wall injected in e has occurred, due to the potential barrier associated with the steep ledge of the sawtooth structure. The scale bar in b is 5μm long, while those in d–f are 3μm long.

Mentions: The ferroelectric diode structure was therefore designed with a relatively thin parallel-sided region, to encourage domain-wall injection, adjacent to a section of gradual thickness increase up to a maximum point, followed by a sudden drop to another parallel-sided region of intermediate thickness (in which it was hoped domain-wall injection would be suppressed in comparison to the thin region); a schematic is shown in Fig. 3a. The resultant cross-sectional sawtooth morphology of the lamella (equivalent to a sawtooth domain-wall potential profile) can be seen in Fig. 3b,c showing a scanning electron microscopy image and AFM topography profile, respectively, of the integrated capacitor structure.


A diode for ferroelectric domain-wall motion.

Whyte JR, Gregg JM - Nat Commun (2015)

The ferroelectric domain-wall diode.Schematic illustration of a KTP lamella with a sawtooth cross-sectional morphology, straddling an interelectrode gap, in a coplanar capacitor device (a). The real device was imaged (b) using SEM (52° tilt); in c, a line profile of the lamellar surface topography along with a plan-view AFM image (inset), with the location at which the line profile was taken marked in red, are presented. The domain-wall injection and motion associated with switching this device are presented in d–f. In each case, the cross-sectional morphology (top) is aligned with the plan-view PFM amplitude (middle) and phase (bottom). The panels in d illustrate the initial fully poled monodomain state after the application of +100 V bias pulse. In e, a partially switched state (after the application of −55 V) is given: a new domain wall has been injected and progressed from right to left up the ramp and over the sawtooth edge. In f, the state after a further bias pulse (+32 V) was applied in the original poling sense is presented: a domain wall of the opposite polarity has been injected into the device and moved to the base of the ramp. Little movement in the original wall injected in e has occurred, due to the potential barrier associated with the steep ledge of the sawtooth structure. The scale bar in b is 5μm long, while those in d–f are 3μm long.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: The ferroelectric domain-wall diode.Schematic illustration of a KTP lamella with a sawtooth cross-sectional morphology, straddling an interelectrode gap, in a coplanar capacitor device (a). The real device was imaged (b) using SEM (52° tilt); in c, a line profile of the lamellar surface topography along with a plan-view AFM image (inset), with the location at which the line profile was taken marked in red, are presented. The domain-wall injection and motion associated with switching this device are presented in d–f. In each case, the cross-sectional morphology (top) is aligned with the plan-view PFM amplitude (middle) and phase (bottom). The panels in d illustrate the initial fully poled monodomain state after the application of +100 V bias pulse. In e, a partially switched state (after the application of −55 V) is given: a new domain wall has been injected and progressed from right to left up the ramp and over the sawtooth edge. In f, the state after a further bias pulse (+32 V) was applied in the original poling sense is presented: a domain wall of the opposite polarity has been injected into the device and moved to the base of the ramp. Little movement in the original wall injected in e has occurred, due to the potential barrier associated with the steep ledge of the sawtooth structure. The scale bar in b is 5μm long, while those in d–f are 3μm long.
Mentions: The ferroelectric diode structure was therefore designed with a relatively thin parallel-sided region, to encourage domain-wall injection, adjacent to a section of gradual thickness increase up to a maximum point, followed by a sudden drop to another parallel-sided region of intermediate thickness (in which it was hoped domain-wall injection would be suppressed in comparison to the thin region); a schematic is shown in Fig. 3a. The resultant cross-sectional sawtooth morphology of the lamella (equivalent to a sawtooth domain-wall potential profile) can be seen in Fig. 3b,c showing a scanning electron microscopy image and AFM topography profile, respectively, of the integrated capacitor structure.

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.