scholarly journals Characterization and Modeling of Spin-Transfer Torque (STT) Magnetic Memory for Computing Applications

2021 ◽  
pp. 51-62
Author(s):  
Roberto Carboni
Keyword(s):  
Computer Architecture ◽  
Random Number Generator ◽  
Data Communication ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Magnetic Memory ◽  
Von Neumann ◽  
Stochastic Computing ◽  
Performance Limitation ◽  
Memory Applications

AbstractWith the ubiquitous diffusion of mobile computing and Internet of Things (IoT), the amount of data exchanged and processed over the internet is increasing every day, demanding secure data communication/storage and new computing primitives. Although computing systems based on microelectronics steadily improved over the past 50 years thanks to the aggressive technological scaling, their improvement is now hindered by excessive power consumption and inherent performance limitation associated to the conventional computer architecture (von Neumann bottleneck). In this scenario, emerging memory technologies are gaining interest thanks to their non-volatility and low power/fast operation. In this chapter, experimental characterization and modeling of spin-transfer torque magnetic memory (STT-MRAM) are presented, with particular focus on cycling endurance and switching variability, which both present a challenge towards STT-based memory applications. Then, the switching variability in STT-MRAM is exploited for hardware security and computing primitives, such as true-random number generator (TRNG) and stochastic spiking neuron for neuromorphic and stochastic computing.

Double Magnetic Tunnel Junction with switchable assistance layer for improved spin transfer torque magnetic memory performance

Nanoscale ◽  
2021 ◽  
Author(s):  
Daniel Sanchez Hazen ◽  
Stephane Auffret ◽  
Isabelle Joumard ◽  
Laurent Vila ◽  
Liliana Buda-Prejbeanu ◽  
...  
Keyword(s):  
Tunnel Junction ◽  
Memory Performance ◽  
Magnetic Tunnel Junction ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Magnetic Memory ◽  
Memory Cells ◽  
Experimental Demonstration

This paper reports the first experimental demonstration of a new concept of double magnetic tunnel junction comprising a magnetically switchable assistance layer. These double junctions are used as memory cells...

scholarly journals Ultrathin perpendicular magnetic anisotropy CoFeB free layers for highly efficient, high speed writing in spin-transfer-torque magnetic random access memory

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jodi M. Iwata-Harms ◽  
Guenole Jan ◽  
Santiago Serrano-Guisan ◽  
Luc Thomas ◽  
Huanlong Liu ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
High Speed ◽  
Random Access ◽  
Perpendicular Magnetic Anisotropy ◽  
Spin Transfer Torque ◽  
Tunnel Barrier ◽  
Magnetic Memory ◽  
Material System ◽  
Highly Efficient ◽  
Memory Applications

AbstractPerpendicular magnetic anisotropy (PMA) ferromagnetic CoFeB with dual MgO interfaces is an attractive material system for realizing magnetic memory applications that require highly efficient, high speed current-induced magnetic switching. Using this structure, a sub-nanometer CoFeB layer has the potential to simultaneously exhibit efficient, high speed switching in accordance with the conservation of spin angular momentum, and high thermal stability owing to the enhanced interfacial PMA that arises from the two CoFeB-MgO interfaces. However, the difficulty in attaining PMA in ultrathin CoFeB layers has imposed the use of thicker CoFeB layers which are incompatible with high speed requirements. In this work, we succeeded in depositing a functional CoFeB layer as thin as five monolayers between two MgO interfaces using magnetron sputtering. Remarkably, the insertion of Mg within the CoFeB gave rise to an ultrathin CoFeB layer with large anisotropy, high saturation magnetization, and good annealing stability to temperatures upwards of 400 °C. When combined with a low resistance-area product MgO tunnel barrier, ultrathin CoFeB magnetic tunnel junctions (MTJs) demonstrate switching voltages below 500 mV at speeds as fast as 1 ns in 30 nm devices, thus opening a new realm of high speed and highly efficient nonvolatile memory applications.

scholarly journals A Physics-Based Compact Model of Stochastic Switching in Spin-Transfer Torque Magnetic Memory

2019 ◽  
Vol 66 (10) ◽  
pp. 4176-4182 ◽  
Author(s):  
Roberto Carboni ◽  
Elena Vernocchi ◽  
Manzar Siddik ◽  
Jon Harms ◽  
Andy Lyle ◽  
...  
Keyword(s):  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Compact Model ◽  
Magnetic Memory ◽  
Stochastic Switching

Integration of STT-MRAMs for Embedded Cache Memories

2014 ◽  
Vol 95 ◽  
pp. 146-149
Author(s):  
Toshihiro Sugii ◽  
Yoshihisa Iba ◽  
Masaki Aoki ◽  
Hideyuki Noshiro ◽  
Kouji Tsunoda ◽  
...  
Keyword(s):  
Dielectric Breakdown ◽  
Magnetic Tunnel Junction ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Cache Memory ◽  
Current Status ◽  
Cache Memories ◽  
Time Dependent Dielectric Breakdown ◽  
Memory Applications ◽  
Embedded Sram

We report the current status of our development of spin-transfer torque magnetic RAMs (STT-MRAMs) and their integration with the back-end-of-line (BEOL) process to replace conventional embedded SRAM cache memories. Our MRAM technology features a top-pinned, perpendicular magnetic tunnel junction (MTJ) and a highly reliable MTJ for a cache memory. We could obtain a higher density cache memory than that with conventional SRAMs with our STT-MRAMs, and leakage free characteristics, as well as unlimited write and read cycling times and 10-year time-dependent dielectric breakdown (TDDB) characteristics. They were integrated into Cu interconnects with 300 mm facilities. We also discuss variations in MTJ pattern sizes that are very important for memory applications from the viewpoint of high density embedded cache memories.

Spin-transfer magnetic random access memory devices with an orthogonal polarizing layer

2014 ◽  
Vol 28 (12) ◽  
pp. 1430005 ◽  
Author(s):  
Huanlong Liu
Keyword(s):  
Random Access ◽  
Random Access Memory ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Switching Process ◽  
Access Memory ◽  
Time Resolved ◽  
Metal Structures ◽  
Magnetic Random Access Memory ◽  
Memory Applications

Spin-transfer magnetic random access memory (MRAM) devices with a polarizing layer magnetized perpendicular to the free and the reference layers are believed to improve the writing performance by inducing a large spin-transfer torque on the free layer at the beginning of the switching process. Experimental realizations of such devices, both with all-metal structures and magnetic tunnel junctions have been made. Faster switching with less energy cost in the orthogonal devices has been achieved comparing to their collinear counterparts. In addition, the processional switching process in such devices has been demonstrated in both statistical and time-resolved measurements. Although further theoretical and material studies are needed for thorough understanding of the switching process and improving the device performance, the orthogonal MRAM devices hold great potential for memory applications operating at low temperatures as well as those that require fast writing speed.

Perpendicular Magnetic Anisotropy in Amorphous Ferromagnetic CoSiB/Pd Thin-Film Layered Structures

2015 ◽  
Vol 15 (10) ◽  
pp. 8336-8339 ◽  
Author(s):  
Sol Jung ◽  
Haein Yim
Keyword(s):  
Magnetic Anisotropy ◽  
Saturation Magnetization ◽  
Random Access ◽  
Perpendicular Magnetic Anisotropy ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Access Memory ◽  
Magnetic Random Access Memory ◽  
Strong Candidate ◽  
Memory Applications

Spin transfer torque (STT) induced switching of magnetization has led to intriguing and practical possibilities for magnetic random access memory (MRAM). This form of memory, called STT-MRAM, is a strong candidate for future memory applications. This application usually requires a large perpendicular magnetic anisotropy (PMA), large coercivity, and low saturation magnetization. Therefore, we propose an amorphous ferromagnetic CoSiB alloy and investigate CoSiB/Pd multilayer thin films, which have a large PMA, large coercivity, and low saturation magnetization. In this research, we propose a remarkable layered structure that could be a candidate for future applications and try to address a few factors that might affect the variation of PMA, coercivity, and saturation magnetization in the CoSiB/Pd multilayers. We investigate the magnetic properties of the CoSiB/Pd multilayers with various thicknesses of the CoSiB layer. The coercivity was obtained with a maximum of 228 Oe and a minimum value of 91 Oe in the [CoSiB 7 Å/Pd 14 Å]5 and [CoSiB 9 Å/Pd 14 Å]5 multilayers, respectively. The PMA arises from tCoSiB = 3 Å to tCoSiB = 9 Å and disappears after tCoSiB = 9 Å.

scholarly journals Spin-Transfer Torque Magnetic Memory as a Stochastic Memristive Synapse for Neuromorphic Systems

2015 ◽  
Vol 9 (2) ◽  
pp. 166-174 ◽  
Author(s):  
Adrien F. Vincent ◽  
Jerome Larroque ◽  
Nicolas Locatelli ◽  
Nesrine Ben Romdhane ◽  
Olivier Bichler ◽  
...  
Keyword(s):  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Magnetic Memory ◽  
Neuromorphic Systems

Design and Analysis of Radiation Hardened Sensing Circuits for Spin Transfer Torque Magnetic Memory and Logic

2014 ◽  
Vol 61 (6) ◽  
pp. 3258-3264 ◽  
Author(s):  
Djaafar Chabi ◽  
Weisheng Zhao ◽  
Jacques-Olivier Klein ◽  
Claude Chappert
Keyword(s):  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Magnetic Memory ◽  
Radiation Hardened

scholarly journals Spin Torque Oscillator for High Performance Magnetic Memory

2015 ◽  
Vol 20 (1) ◽  
pp. 77
Author(s):  
Rachid Sbiaa ◽  
Khaled Bouziane
Keyword(s):  
High Performance ◽  
Perpendicular Magnetic Anisotropy ◽  
Magnetic Tunnel Junction ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Magnetic Memory ◽  
Spin Torque ◽  
Free Layer ◽  
Switching Current ◽  
Thermal Stability Of

A study on spin transfer torque switching in a magnetic tunnel junction with perpendicular magnetic anisotropy is presented. The switching current can be strongly reduced under a spin torque oscillator (STO), and its use in addition to the conventional transport in magnetic tunnel junctions (MTJ) should be considered. The reduction of the switching current from the parallel state to the antiparallel state is greater than in  the opposite direction, thus minimizing the asymmetry of the resistance versus current in the hysteresis loop. This reduction of both switching current and asymmetry under a spin torque oscillator occurs only during the writing process and does not affect the thermal stability of the free layer.

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