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

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.

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

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2015.11250 ◽

2015 ◽

Vol 15 (10) ◽

pp. 8336-8339 ◽

Cited By ~ 3

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.

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NONVOLATILE SPINTRONICS: PERSPECTIVES ON INSTANT-ON NONVOLATILE NANOELECTRONIC SYSTEMS

SPIN ◽

10.1142/s2010324712500099 ◽

2012 ◽

Vol 02 (02) ◽

pp. 1250009 ◽

Cited By ~ 21

Author(s):

K. L. WANG ◽

P. KHALILI AMIRI

Keyword(s):

Energy Dissipation ◽

Nonvolatile Memory ◽

High Speed ◽

Logic Gate ◽

Random Access ◽

Spin Transfer Torque ◽

Magnetic Memory ◽

New Paradigm ◽

Cmos Scaling ◽

Switching Energy

Instant-on nonvolatile electronics, which can be powered on/off instantaneously without the loss of information, represents a new and emerging paradigm in electronics. Nonvolatile circuits consisting of volatile CMOS, combined with nonvolatile nanoscale magnetic memory, can make electronics nonvolatile at the gate, circuit and system levels. When high speed magnetic memory is embedded in CMOS logic circuits, it may help resolve the two major challenges faced in continuing CMOS scaling: Power dissipation and variability of devices. We will give a brief overview of the current challenges of CMOS in terms of energy dissipation and variability. Then, we describe emerging nonvolatile memory (NVM) options, particularly those spintronic solutions such as magnetoresistive random access memory (MRAM) based on spin transfer torque (STT) and voltage-controlled magnetoelectric (ME) write mechanisms. We will then discuss the use of STT memory for embedded application, e.g., replacing volatile CMOS Static RAM (SRAM), followed by discussion of integration of CMOS reconfigurable circuits with STT-RAM. We will then present the scaling limits of the STT memory and discuss its critical performance parameters, particularly related to switching energy. To further reduce the switching energy, we present the concept of electric field control of magnetism, and discuss approaches to realize this new mechanism in realizing low switching energy, allowing for implementation of nonvolatility at the logic gate level, and eventually at the transistor level with a magnetoelectric gate (MeGate). For nonvolatile logic (NVL), we present and discuss as an example an approach using interference of spin waves, which will have NVL operations remembering the state of computation. Finally, we will discuss the potential impact and implications of this new paradigm on low energy dissipation instant-on nonvolatile systems.

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SPIN TRANSFER TORQUE SWITCHING AND PERPENDICULAR MAGNETIC ANISOTROPY IN FULL HEUSLER ALLOY Co2FeAl-BASED TUNNEL JUNCTIONS

SPIN ◽

10.1142/s2010324714400232 ◽

2014 ◽

Vol 04 (04) ◽

pp. 1440023 ◽

Cited By ~ 7

Author(s):

H. SUKEGAWA ◽

Z. C. WEN ◽

S. KASAI ◽

K. INOMATA ◽

S. MITANI

Keyword(s):

Magnetic Anisotropy ◽

Tunnel Junctions ◽

Heusler Alloys ◽

Random Access ◽

Perpendicular Magnetic Anisotropy ◽

Spin Transfer Torque ◽

Spin Transfer ◽

High Spin Polarization ◽

Full Heusler ◽

Full Heusler Alloys

Some of Co -based full Heusler alloys have remarkable properties in spintronics, that is, high spin polarization of conduction electrons and low magnetic damping. Owing to these properties, magnetic tunnel junctions (MTJs) using Co -based full Heusler alloys are potentially of particular importance for spintronic application such as magnetoresistive random access memories (MRAMs). Recently, we have first demonstrated spin transfer torque (STT) switching and perpendicular magnetic anisotropy (PMA), which are required for developing high-density MRAMs, in full-Heusler Co 2 FeAl alloy-based MTJs. In this review, the main results of the experimental demonstrations are shown with referring to related issues, and the prospect of MTJs using Heusler alloys is also discussed.

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Nanoscale Materials for State-of-the-Art Magnetic Memory Technologies

Uspehi Fiziki Metallov ◽

10.15407/ufm.22.02.175 ◽

2021 ◽

Vol 22 (2) ◽

pp. 175-203

Author(s):

A. E. Hafarov ◽

S. M. Voloshko ◽

A. Kaidatzis ◽

I. A. Vladymyrskyi

Keyword(s):

Magnetic Anisotropy ◽

Materials Science ◽

State Of The Art ◽

Random Access ◽

Perpendicular Magnetic Anisotropy ◽

Random Access Memory ◽

Magnetic Memory ◽

Nanoscale Materials ◽

Access Memory ◽

Magnetoresistive Random Access Memory

The review deals with different materials science aspects of state-of-the-art magnetic memory technologies, such as magnetoresistive random-access memory (MRAM), antiferromagnetic (AFM) memory, and skyrmion racetrack memory. Particularly, the materials with high perpendicular magnetic anisotropy (PMA), such as CoFeB, L10-ordered Mn- and Fe-based alloys, are considered (Sec. 1) regarding their applications in MRAM technology. Furthermore, studies of AFM alloys, such as FeRh, CuMnAs, Mn2Au, are reviewed (Sec. 2) with an emphasis on the application of these materials in AFM-memory technology. Finally, the last (3rd) section of the review is concerning materials that could be used in skyrmion racetrack memory.

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Interfacial Perpendicular Magnetic Anisotropy in Sub-20 nm Tunnel Junctions for Large-Capacity Spin-Transfer Torque Magnetic Random-Access Memory

IEEE Magnetics Letters ◽

10.1109/lmag.2017.2693961 ◽

2017 ◽

Vol 8 ◽

pp. 1-5 ◽

Cited By ~ 9

Author(s):

Shouzhong Peng ◽

Wang Kang ◽

Mengxing Wang ◽

Kaihua Cao ◽

Xiaoxuan Zhao ◽

...

Keyword(s):

Magnetic Anisotropy ◽

Tunnel Junctions ◽

Random Access ◽

Perpendicular Magnetic Anisotropy ◽

Random Access Memory ◽

Spin Transfer Torque ◽

Spin Transfer ◽

Access Memory ◽

Magnetic Random Access Memory ◽

20 Nm

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Reduced Thermal Variation of Perpendicular Magnetic Anisotropy in Magnetically Stiffened Dual-W Composite Storage Layer for Spin-Transfer-Torque Magnetic Random-Access Memory

Physical Review Applied ◽

10.1103/physrevapplied.12.044043 ◽

2019 ◽

Vol 12 (4) ◽

Cited By ~ 2

Author(s):

Jyotirmoy Chatterjee ◽

Antoine Chavent ◽

Farid Fettar ◽

Stephane Auffret ◽

Clarisse Ducruet ◽

...

Keyword(s):

Magnetic Anisotropy ◽

Random Access ◽

Perpendicular Magnetic Anisotropy ◽

Random Access Memory ◽

Spin Transfer Torque ◽

Spin Transfer ◽

Thermal Variation ◽

Access Memory ◽

Magnetic Random Access Memory

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Highly efficient spin-orbit torque switching in a single GaMnAs thin film with perpendicular magnetic anisotropy

10.7567/ssdm.2019.e-6-05 ◽

2019 ◽

Author(s):

M. Jiang ◽

H. Asahara ◽

S. Sato ◽

T. Kanaki ◽

H. Yamasaki ◽

...

Keyword(s):

Thin Film ◽

Magnetic Anisotropy ◽

Perpendicular Magnetic Anisotropy ◽

Spin Orbit ◽

Highly Efficient

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Investigation of Ni Doped Ge-Te Materials for High Temperature Phase Change Memory Applications

Materials Science Forum ◽

10.4028/www.scientific.net/msf.848.460 ◽

2016 ◽

Vol 848 ◽

pp. 460-465

Author(s):

Liang Liang Cao ◽

Liang Cai Wu ◽

Zhi Tang Song ◽

Wen Qing Zhu ◽

Yong Hui Zheng ◽

...

Keyword(s):

High Temperature ◽

Phase Change ◽

High Speed ◽

Random Access ◽

High Temperature Phase ◽

Temperature Phase ◽

Change Behavior ◽

Transmission Electron ◽

Ni Addition ◽

Memory Applications

Ni-doped Ge-Te (Ni-GT) material was proposed and investigated for phase change random access memory (PCRAM) applications. With Ni addition, the crystallization temperature, data retention ability and crystallization speed were obviously improved. The surface roughness of crystalline Ni-GT films was decreased by Ni incorporation. Moreover, temperature dependent transmission electron microscopy (TEM) was applied to investigate the phase change behavior of Ni-GT films. All the experimental results demonstrated that Ni-GT material has potential for high-speed PCRAM applications in high temperature environment.

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