Time-dependent domain wall nucleation probability in field-coupled nanomagnets with perpendicular anisotropy

Breitkreutz, Stephan; Fischer, Andreas; Kaffah, Silmi; Weigl, Stephanie; Eichwald, Irina; Ziemys, Grazvydas; Schmitt‐Landsiedel, D.; Becherer, Markus

doi:10.1063/1.4906440

Cited by 8 publications

(4 citation statements)

References 17 publications

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“…A second example is the patterned magnetic elements in magnetic random access memories (MRAM) or magnetic logic, which suffer from the thermally activated variations in the switching field [15,16]. Our method allows the determination of the switching field in the absense of thermal fluctuation at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the energy barrier and switching field of sub-micron magnetic islands with perpendicular anisotropy

2017

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Using the highly sensitive anomalous Hall effect we have been able to measure the reversal of a single magnetic island, of diameter 220 nm, in an array consisting of more than 80 of those islands. By repeatedly traversing the hysteresis loop, we measured the thermally induced fluctuation of the switching field of the islands at the lower and higher ends of the switching field distribution. Based on a novel easy-to-use model, we determined the switching field in the absence of thermal activation, and the energy barrier in the absence of an external field from these fluctuations. By measuring the reversal of individual dots in the array as a function of temperature, we extrapolated the switching field and energy barrier down to 0 K. The extrapolated values are not identical to those obtained from the fluctation of the switching field at room temperature, because the properties of the magnetic material are temperature dependent. As a result, extrapolating from temperature dependent measurements overestimates the energy barrier by more than a factor of two. To determine fundamental parameters of the energy barrier between magnetisation states, measuring the fluctuation of the reversal field at the temperature of application is therefore to be preferred. This is of primary importance to applications in data storagea and magnetic logic. For instance in fast switching, where the switching field in the absence of thermal activation plays a major role, or in long term data stability, which is determined by the energy barrier in the absence of an external field.

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Section: Introductionmentioning

confidence: 99%

Temperature dependence of the energy barrier and switching field of sub-micron magnetic islands with perpendicular anisotropy

2017

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“…In perpendicular materials nucleation is a strongly thermally activated process and so can vary dramatically for small changes in sample or applied field conditions. It has been shown that for dipole coupled perpendicular magnets that switching times of the order of tens of nanoseconds are to be expected [22]. Therefore an optimized system may be able to operate in the 10-100 MHz range.…”

Section: Discussionmentioning

confidence: 99%

A magnetic shift register with out-of-plane magnetized layers

et al. 2017

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Using out-of-plane magnetized layers, a lateral shift register made from discrete elements is demonstrated. By carefully designing the in-plane shape of the elements which make up the shift register, both the position of nucleation of new domains and the coercivity of the element can be controlled. The dipole field from a neighboring element, placed tens of nanometers away, creates a bias field on the nucleation site, which can be used to create a NOT gate. By chaining these NOT gates together, a shift register can be created where data bits consisting of neighboring layers with aligned magnetization are propagated synchronously under a symmetric applied magnetic field. The operation of a 16 element shift register is shown, including field coupled data injection.

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“…The ANC is the point where the domain is nucleated and then it spreads over the whole magnet. [9][10][11] In this paper we investigated the magnetization reversal behavior at an ANC assisted by an external field by thermal micromagnetic simulations.…”

Section: Pnml Technologymentioning

confidence: 99%

Experiment-based thermal micromagnetic simulations of the magnetization reversal for ns-range clocked nanomagnetic logic

et al. 2017

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Extensive thermal micromagnetic simulations, based on experimental data and parameters, were performed to investigate the magnetization reversal in Co/Pt nanomagnets with locally reduced perpendicular anisotropy on the nanosecond range. The simulations were supported by experimental data gained on manufactured Co/Pt nanomagnets, as used in nanomagnetic logic. It is known that magnetization reversal is governed by two mechanisms. At pulse lengths longer than 100 ns, thermal activation dominates the magnetization reversal processes and follows the common accepted Arrhenius law. For pulse lengths shorter than 100 ns, the dynamic reversal dominates. With the help of thermal micro-magnetic simulations we found out that the point where the both mechanisms meet is determined by the damping constant α of the multilayer film stack. The optimization of ferromagnetic multilayer film stacks enables higher clocking rates with lower power consumption and, therefore, further improve the performance of pNML.

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Time-dependent domain wall nucleation probability in field-coupled nanomagnets with perpendicular anisotropy

Cited by 8 publications

References 17 publications

Temperature dependence of the energy barrier and switching field of sub-micron magnetic islands with perpendicular anisotropy

Temperature dependence of the energy barrier and switching field of sub-micron magnetic islands with perpendicular anisotropy

A magnetic shift register with out-of-plane magnetized layers

Experiment-based thermal micromagnetic simulations of the magnetization reversal for ns-range clocked nanomagnetic logic

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