scholarly journals Current-induced crystallisation in Heusler alloy films for memory potentiation in neuromorphic computation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
William Frost ◽  
Kelvin Elphick ◽  
Marjan Samiepour ◽  
Atsufumi Hirohata
Keyword(s):  
Heusler Alloy ◽  
Layer Growth ◽  
Layer By Layer ◽  
Half Metallic ◽  
Alloy Films ◽  
Von Neumann ◽  
Alternative Technologies ◽  
Artificial Synapse ◽  
Neumann Type ◽  
Area Product

AbstractThe current information technology has been developed based on von Neumann type computation. In order to sustain the rate of development, it is essential to investigate alternative technologies. In a next-generation computation, an important feature is memory potentiation, which has been overlooked to date. In this study, potentiation functionality is demonstrated in a giant magnetoresistive (GMR) junction consisting of a half-metallic Heusler alloy which can be a candidate of an artificial synapse while still achieving a low resistance-area product for low power consumption. Here the Heusler alloy films are grown on a (110) surface to promote layer-by-layer growth to reduce their crystallisation energy, which is comparable with Joule heating induced by a controlled current introduction. The current-induced crystallisation leads to the reduction in the corresponding resistivity, which acts as memory potentiation for an artificial GMR synaptic junction.

scholarly journals Current-Induced Crystallisation in Heusler Alloy Films for Memory Potentiation in Neuromorphic Computation

2021 ◽  
Author(s):  
William Frost ◽  
Kelvin Elphick ◽  
Marjan Samiepour ◽  
Atsufumi Hirohata
Keyword(s):  
Heusler Alloy ◽  
Magnetic Tunnel Junction ◽  
Complementary Metal Oxide Semiconductor ◽  
Layer Growth ◽  
Oxide Semiconductor ◽  
Layer By Layer ◽  
Alloy Films ◽  
Von Neumann ◽  
Alternative Technologies ◽  
Area Product

Abstract The current information technology has been developed based on von Neumann type computation. In order to sustain the rate of development, it is essential to investigate alternative technologies. Among them, neuromorphic computation has been attracting intensive studies using the current complementary metal oxide semiconductor (CMOS) architecture and beyond in recent years to mimic the functionality and operation of a synapse in a brain. One of the promising synapses is stochastic operation of a magnetic tunnel junction (MTJ). However another important feature of a synapse, memory potentiation, has been overlooked to date. In this study, a giant magnetoresistive (GMR) junction consisting of a half-metallic Heusler alloy is used as an artificial synapse while still achieving a low resistance-area product for low power consumption. Here the Heusler alloy films are grown on a (110) surface to promote layer-by-layer growth to reduce their crystallisation energy, which is comparable with Joule heating induced by a controlled current introduction. The current-induced crystallisation leads to the reduction in the corresponding resistivity, which acts as memory potentiation for an artificial GMR synapse. This offers more realistic neuromorphic computation with higher efficiency.

scholarly journals Low magnetic damping and large negative anisotropic magnetoresistance in half-metallic Co2−xMn1+xSi Heusler alloy films grown by molecular beam epitaxy

2018 ◽  
Vol 112 (26) ◽  
pp. 262407 ◽  
Author(s):  
Mikihiko Oogane ◽  
Anthony P. McFadden ◽  
Kenji Fukuda ◽  
Masakiyo Tsunoda ◽  
Yasuo Ando ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Heusler Alloy ◽  
Molecular Beam ◽  
Anisotropic Magnetoresistance ◽  
Half Metallic ◽  
Alloy Films ◽  
Magnetic Damping

Electronic Structure and Spin-Injection of Co-Based Heusler Alloy/ Semiconductor Junctions

2011 ◽  
Vol 470 ◽  
pp. 54-59
Author(s):  
Hiroyoshi Itoh ◽  
Syuta Honda ◽  
Junichiro Inoue
Keyword(s):  
Electronic Structure ◽  
Heusler Alloy ◽  
Spin Injection ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
Growth Direction ◽  
Layer By Layer ◽  
Half Metallicity ◽  
Half Metallic ◽  
Layer Stacking

The electronic structures of Co-based Heusler alloys with nonstoichiometric atomic compositions as well as those at the interface of semiconductor junctions are investigated using first principles band calculations. It is shown that the electronic structure of a Co-based Heusler alloy is half-metallic, even for nonstoichiometric but Co-rich compositions, whereas the half-metallicity is lost for Co-poor compositions. It is also shown that magnetic moments at the interface of Co2MnSi/ Si junctions are sensitive to the growth direction and interface structure of the junctions. Efficient spin-injection into Si can be achieved by using a (111)-oriented Co-rich Heusler alloy and controlling the layer-by-layer stacking sequence at the interface.

scholarly journals Ultrafast demagnetization for Ni80Fe20and half-metallic Co2MnSi heusler alloy films

2010 ◽  
Vol 200 (4) ◽  
pp. 042017 ◽  
Author(s):  
S Mizukami ◽  
S Tsunegi ◽  
T Kubota ◽  
M Oogane ◽  
D Watanabe ◽  
...  
Keyword(s):  
Heusler Alloy ◽  
Half Metallic ◽  
Alloy Films ◽  
Ultrafast Demagnetization

Oblique-incidence Reflectivity Difference (OI-RD) and Leed Studies of Adsorption and Growth of Xe on Nb(110)

2003 ◽  
Vol 780 ◽  
Author(s):  
P. Thomas ◽  
E. Nabighian ◽  
M.C. Bartelt ◽  
C.Y. Fong ◽  
X.D. Zhu
Keyword(s):  
Transition Layer ◽  
Layer Growth ◽  
Flow Mode ◽  
Layer By Layer ◽  
Zeroth Order ◽  
Step Flow ◽  
Low Energy Electron Diffraction ◽  
Oriented Film ◽  
Low Energy Electron

AbstractWe studied adsorption, growth and desorption of Xe on Nb(110) using an in-situ obliqueincidence reflectivity difference (OI-RD) technique and low energy electron diffraction (LEED) from 32 K to 100 K. The results show that Xe grows a (111)-oriented film after a transition layer is formed on Nb(110). The transition layer consists of three layers. The first two layers are disordered with Xe-Xe separation significantly larger than the bulk value. The third monolayer forms a close packed (111) structure on top of the tensile-strained double layer and serves as a template for subsequent homoepitaxy. The adsorption of the first and the second layers are zeroth order with sticking coefficient close to one. Growth of the Xe(111) film on the transition layer proceeds in a step flow mode from 54K to 40K. At 40K, an incomplete layer-by-layer growth is observed while below 35K the growth proceeds in a multilayer mode.

scholarly journals Modeling the Layer-by-Layer Growth of HKUST-1 Metal-Organic Framework Thin Films

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1631
Author(s):  
Qiang Zhang ◽  
Yohanes Pramudya ◽  
Wolfgang Wenzel ◽  
Christof Wöll
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Deposition Rate ◽  
Layer Growth ◽  
Coarse Grained ◽  
Structural Defects ◽  
Effect Of Temperature ◽  
Layer By Layer ◽  
Reactant Concentration ◽  
Metal Organic

Metal organic frameworks have emerged as an important new class of materials with many applications, such as sensing, gas separation, drug delivery. In many cases, their performance is limited by structural defects, including vacancies and domain boundaries. In the case of MOF thin films, surface roughness can also have a pronounced influence on MOF-based device properties. Presently, there is little systematic knowledge about optimal growth conditions with regard to optimal morphologies for specific applications. In this work, we simulate the layer-by-layer (LbL) growth of the HKUST-1 MOF as a function of temperature and reactant concentration using a coarse-grained model that permits detailed insights into the growth mechanism. This model helps to understand the morphological features of HKUST-1 grown under different conditions and can be used to predict and optimize the temperature for the purpose of controlling the crystal quality and yield. It was found that reactant concentration affects the mass deposition rate, while its effect on the crystallinity of the generated HKUST-1 film is less pronounced. In addition, the effect of temperature on the surface roughness of the film can be divided into three regimes. Temperatures in the range from 10 to 129 °C allow better control of surface roughness and film thickness, while film growth in the range of 129 to 182 °C is characterized by a lower mass deposition rate per cycle and rougher surfaces. Finally, for T larger than 182 °C, the film grows slower, but in a smooth fashion. Furthermore, the potential effect of temperature on the crystallinity of LbL-grown HKUST-1 was quantified. To obtain high crystallinity, the operating temperature should preferably not exceed 57 °C, with an optimum around 28 °C, which agrees with experimental observations.

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