Realization of 10Tbit∕in.2 memory density and subnanosecond domain switching time in ferroelectric data storage

Cho, Yasuo; Hashimoto, Sunao; Odagawa, Nozomi; Tanaka, Kenkou; Hiranaga, Yoshiomi

doi:10.1063/1.2140894

Cited by 71 publications

(48 citation statements)

References 6 publications

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“…Isolated wedge-shaped domains are formed under the charged SPM probe which then grow through the uniaxial ferroelectric of nano-, micro-or millimeter thickness acquiring an almost cylindrical shape or a slightly truncated cone [7,8,9,10] or long needles [11,12,13,14]. Note, that from one to three orders of magnitude increase of the bulk conductivity along the atrificially produced charged domain wall has been measured in single crystal of ferroelectric-semiconductor SbSJ [12].…”

Section: Introductionmentioning

confidence: 99%

Static conductivity of charged domain walls in uniaxial ferroelectric semiconductors

Eliseev

Morozovska²,

Svechnikov³

et al. 2011

Phys. Rev. B

234

205

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Using Landau-Ginzburg-Devonshire theory we calculated numerically the static conductivity of charged domain walls with different incline angle with respect to spontaneous polarization vector in the uniaxial ferroelectrics-semiconductors of n-type. We used the effective mass approximation for the electron and holes density of states, which is valid at arbitrary distance from the domain wall.Due to the electrons accumulation, the static conductivity drastically increases at the inclined head-to-head wall by 1 order of magnitude for small incline angles θ~π/40 by up 3 orders of magnitude for the perpendicular domain wall (θ=π/2).There are space charge regions around the charged domain walls, but the quantitative characteristics of the regions (width and distribution of the carriers) appeared very different for the tail-to-tail and head-to-head walls in the considered donor doped ferroelectric semiconductor.The head-to-head wall is surrounded by the space charge layer with accumulated electrons and depleted donors of the same thickness (~40−100 correlation lengths). The tail-to-tail wall is surrounded by the thin space charge layer with accumulated holes of thickness ~5-10 correlation lengths and thick layer with accumulated donors of thickness ~100−200 correlation lengths, as well as the layer with depleted by electrons of thickness ~100−200 correlation lengths.* Corresponding author, e-mail: morozo@i.com.ua † Corresponding author, e-mail: vladimir.shur@usu.ru 2 The conductivity across the tail-to-tail wall is at least an order of magnitude smaller than the one of the head-to-head wall due to the low mobility of holes, which are improper carries.The results are in qualitative agreement with recent experimental data for LiNbO 3 doped with MgO.

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Section: Introductionmentioning

confidence: 99%

Static conductivity of charged domain walls in uniaxial ferroelectric semiconductors

Eliseev

Morozovska²,

Svechnikov³

et al. 2011

Phys. Rev. B

234

205

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“…On the contrary, internal clamping of the material reduces the observed deformation compared to the theoretically expected value which depends only on the voltage thus being independent of the exact field distribution. Ferroelectric domain patterns are the basis of a multitude of applications such as quasi-phase-matched frequency converters [1], electro-optic scanners [2], nonlinear photonic crystals [3], and ultra-high density data storage devices [4]. For further improvement of the domain patterns their visualization with high lateral resolution is indispensable.…”

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confidence: 99%

Influence of the inhomogeneous field at the tip on quantitative piezoresponse force microscopy

2006

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Ferroelectric domain imaging with piezoresponse force microscopy (PFM) relies on the converse piezoelectric effect: a voltage applied to the sample leads to mechanical deformations. In case of PFM one electrode is realized by the tip, therefore generating a strongly inhomogeneous electric field distribution inside the sample which reaches values up to 10 8 V/m directly underneath the apex of the tip. Although often assumed, this high electric field does not lead to an enhancement of the piezoelectric deformation of the sample. On the contrary, internal clamping of the material reduces the observed deformation compared to the theoretically expected value which depends only on the voltage thus being independent of the exact field distribution. [5], piezoresponse force microscopy (PFM) has become a standard technique in recent years mainly because of its easy use. However, the interpretation of the obtained images is still challenging, therefore quantitative data is published very rarely. This deficiency is often justified by the presumption that due to the strong dependency of the electric field on the tip radius, which in general is not known exactly, a quantitative analysis of the data is not possible. Arguing that way, however, ignores the fact that, at least in a first approximation, not the electric field distribution but only the applied voltage determines the piezoelectric deformation of the sample. Although this statement is self-evident from theoretical considerations, we carried out experiments with different single-domain crystals, comparing the measured deformation underneath the tip with and without an additional top electrode.PFM is based on the deformation of the sample due to the converse piezoelectric effect. The piezoresponse force microscope is a scanning force microscope (SFM) operated in contact mode with an additional alternating voltage applied to the tip. In piezoelectric samples this voltage causes thickness changes and therefore vibrations of the surface which lead to oscillations of the cantilever that can be read out with a lock-in amplifier. In ferroelectric samples different orientations of the polar axis of adjacent domains lead to a domain contrast, i. e., the domain faces are displayed as bright or dark areas in PFM images (an overview of the PFM technique can be found in [6]). The generally observed frequency * Electronic address: soergel@uni-bonn.de dependence of those measurements [7,8,9] was recently be explained by a system-inherent background [10]. We also proposed a detection scheme that allows a straight forward quantitative analysis of the obtained data [11]. In this contribution we investigate the influence of the strongly inhomogeneous electric field of the tip on the piezoelectric deformation measured with PFM.The (longitudinal) converse piezoelectric effect says that in an external electric field E a piezoelectric material of thickness t undergoes a thickness change ∆t proportional to the appropriate piezoelectric coefficient d:Note that the thickness change ∆t does n...

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“…Since the tiniest units of information are found in non-volatile storage systems (such as the hard disk), the first encounter with those limits was found in that area, where it expressed itself in the thermal stability of written bits [1]. Non-volatile data storage will therefore move away from magnetism, possibly in the direction of ferro-electrics [2] or phase-change [3]. Ultimately, we will store bits of information into single atoms [4].…”

Section: Introductionmentioning

confidence: 99%

Self-Assembled Three-Dimensional Non-Volatile Memories

et al. 2010

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Abstract:The continuous increase in capacity of non-volatile data storage systems will lead to bit densities of one bit per atom in 2020. Beyond this point, capacity can be increased by moving into the third dimension. We propose to use self-assembly of nanosized elements, either as a loosely organised associative network or into a cross-point architecture. When using principles requiring electrical connection, we show the need for transistor-based cross-talk isolation. Cross-talk can be avoided by reusing the coincident current magnetic ring core memory architecture invented in 1953. We demonstrate that self-assembly of three-dimensional ring core memories is in principle possible by combining corner lithography and anisotropic etching into single crystal silicon.

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Realization of 10Tbit∕in.2 memory density and subnanosecond domain switching time in ferroelectric data storage

Cited by 71 publications

References 6 publications

Static conductivity of charged domain walls in uniaxial ferroelectric semiconductors

Static conductivity of charged domain walls in uniaxial ferroelectric semiconductors

Influence of the inhomogeneous field at the tip on quantitative piezoresponse force microscopy

Self-Assembled Three-Dimensional Non-Volatile Memories

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