scholarly journals Magnetic memory driven by topological insulators

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hao Wu ◽  
Aitian Chen ◽  
Peng Zhang ◽  
Haoran He ◽  
John Nance ◽  
...  
Keyword(s):  
Energy Efficient ◽  
Topological Insulators ◽  
Random Access ◽  
Magnetic Memory ◽  
Spin Conversion ◽  
Core Element ◽  
Practical Applications ◽  
Spintronic Devices ◽  
Magnetic Switching ◽  
Order Of Magnitude

AbstractGiant spin-orbit torque (SOT) from topological insulators (TIs) provides an energy efficient writing method for magnetic memory, which, however, is still premature for practical applications due to the challenge of the integration with magnetic tunnel junctions (MTJs). Here, we demonstrate a functional TI-MTJ device that could become the core element of the future energy-efficient spintronic devices, such as SOT-based magnetic random-access memory (SOT-MRAM). The state-of-the-art tunneling magnetoresistance (TMR) ratio of 102% and the ultralow switching current density of 1.2 × 105 A cm−2 have been simultaneously achieved in the TI-MTJ device at room temperature, laying down the foundation for TI-driven SOT-MRAM. The charge-spin conversion efficiency θSH in TIs is quantified by both the SOT-induced shift of the magnetic switching field (θSH = 1.59) and the SOT-induced ferromagnetic resonance (ST-FMR) (θSH = 1.02), which is one order of magnitude larger than that in conventional heavy metals. These results inspire a revolution of SOT-MRAM from classical to quantum materials, with great potential to further reduce the energy consumption.

scholarly journals Crystalline Orientation–Dependent Spin Hall Effect in Epitaxial Platinum

2022 ◽  
Vol 9 ◽  
Author(s):  
Yuxuan Xiao ◽  
Hailong Wang ◽  
Eric E. Fullerton
Keyword(s):  
Hall Effect ◽  
Energy Efficient ◽  
Spin Hall Effect ◽  
Spin Torque ◽  
Temperature Dependent ◽  
Spin Conversion ◽  
Crystalline Orientation ◽  
Spintronic Devices ◽  
Crystalline Anisotropy ◽  
Pt Films

We report on the spin Hall effect in epitaxial Pt films with well-defined crystalline (200), (220), and (111) orientations and smooth surfaces. The magnitude of the spin Hall effect has been determined by spin–torque ferromagnetic resonance measurements on epitaxial Pt/Py heterostructures. We observed a 54% enhancement of the charge-to-spin conversion efficiency of the epitaxial Pt when currents are applied along the in-plane <002> direction. Temperature-dependent harmonic measurements on epitaxial Pt/Co/Ni heterostructures compared to a polycrystalline Pt/Co/Ni suggest the extrinsic mechanism underlying spin Hall effect in epitaxial Pt. Our work contributes to the development of energy-efficient spintronic devices by engineering the crystalline anisotropy of non-magnetic metals.

Diagnostics of metal samples using the results of experimental and theoretical study of positively charged microparticles formed upon sample destruction

2018 ◽  
Vol 84 (10) ◽  
pp. 23-28
Author(s):  
D. A. Golentsov ◽  
A. G. Gulin ◽  
Vladimir A. Likhter ◽  
K. E. Ulybyshev
Keyword(s):  
Experimental Data ◽  
Early Stage ◽  
Experimental Studies ◽  
Material Model ◽  
Total Charge ◽  
Cross Sectional ◽  
Practical Applications ◽  
Mechanical And Electrical Properties ◽  
Order Of Magnitude ◽  
Using Data

Destruction of bodies is accompanied by formation of both large and microscopic fragments. Numerous experiments on the rupture of different samples show that those fragments carry a positive electric charge. his phenomenon is of interest from the viewpoint of its potential application to contactless diagnostics of the early stage of destruction of the elements in various technical devices. However, the lack of understanding the nature of this phenomenon restricts the possibility of its practical applications. Experimental studies were carried out using an apparatus that allowed direct measurements of the total charge of the microparticles formed upon sample rupture and determination of their size and quantity. The results of rupture tests of duralumin and electrical steel showed that the size of microparticles is several tens of microns, the particle charge per particle is on the order of 10–14 C, and their amount can be estimated as the ratio of the cross-sectional area of the sample at the point of discontinuity to the square of the microparticle size. A model of charge formation on the microparticles is developed proceeding from the experimental data and current concept of the electron gas in metals. The model makes it possible to determine the charge of the microparticle using data on the particle size and mechanical and electrical properties of the material. Model estimates of the total charge of particles show order-of-magnitude agreement with the experimental data.

scholarly journals Reducing Dzyaloshinskii-Moriya interaction and field-free spin-orbit torque switching in synthetic antiferromagnets

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ruyi Chen ◽  
Qirui Cui ◽  
Liyang Liao ◽  
Yingmei Zhu ◽  
Ruiqi Zhang ◽  
...  
Keyword(s):  
Domain Wall ◽  
Tunnel Junctions ◽  
Low Power Consumption ◽  
Stray Field ◽  
Magnetic Memory ◽  
Spin Orbit ◽  
Theoretic Analysis ◽  
Spintronic Devices ◽  
Deterministic Switching ◽  
Moriya Interaction

AbstractPerpendicularly magnetized synthetic antiferromagnets (SAF), possessing low net magnetization and high thermal stability as well as easy reading and writing characteristics, have been intensively explored to replace the ferromagnetic free layers of magnetic tunnel junctions as the kernel of spintronic devices. So far, utilizing spin-orbit torque (SOT) to realize deterministic switching of perpendicular SAF have been reported while a large external magnetic field is typically needed to break the symmetry, making it impractical for applications. Here, combining theoretic analysis and experimental results, we report that the effective modulation of Dzyaloshinskii-Moriya interaction by the interfacial crystallinity between ferromagnets and adjacent heavy metals plays an important role in domain wall configurations. By adjusting the domain wall configuration between Bloch type and Néel type, we successfully demonstrate the field-free SOT-induced magnetization switching in [Co/Pd]/Ru/[Co/Pd] SAF devices constructed with a simple wedged structure. Our work provides a practical route for utilization of perpendicularly SAF in SOT devices and paves the way for magnetic memory devices with high density, low stray field, and low power consumption.

Heat Compensation in Buildings Using Thermoelectric Windows: An Energy Efficient Window Technology

2008 ◽  
Author(s):  
Rhys-Sheffer Birthwright ◽  
Achille Messac ◽  
Timothy Harren-Lewis ◽  
Sirisha Rangavajhala
Keyword(s):  
Energy Efficient ◽  
Coefficient Of Performance ◽  
Building Structures ◽  
Practical Applications ◽  
Current Input ◽  
Flow Through ◽  
Conventional Systems ◽  
Window Design ◽  
Absorption Power ◽  
Do So

In this paper, we explore the design of thermoelectric (TE) windows for applications in building structures. Thermoelectric windows are equipped with TE units in the window frame to provide a heat absorption power, given a direct current input. We explore the design performance of the TE window to compensate for its own heat gains. While existing energy efficient windows have made advances towards reducing the heat transfer through them, they still depend on the building’s heating, ventilation and air-conditioning (HVAC) system to compensate for their heat gains. Our research explores the design of a window that can actively compensate for the passive heat flow through the window panes, and to do so with a better coefficient of performance (COP) than conventional HVAC systems. We also optimize the TE window design, and present results of the potential performance for practical applications in the building structure. For the geographic locations considered (Hawaii and Miami), the results are promising. Interestingly, the proposed TE window design actively compensates for the conduction heat gains with a COP greater than three, while that of conventional systems is typically less than three.

scholarly journals On the Use of Magnetic RAMs in Field-Programmable Gate Arrays

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Y. Guillemenet ◽  
L. Torres ◽  
G. Sassatelli ◽  
N. Bruchon
Keyword(s):  
Power Consumption ◽  
Random Access ◽  
Switching Scheme ◽  
Fpga Design ◽  
Gate Arrays ◽  
Magnetic Switching ◽  
Field Programmable ◽  
Programmable Gate Arrays ◽  
Time Required ◽  
Magnetic Tunneling

This paper describes the integration of field-induced magnetic switching (FIMS) and thermally assisted switching (TAS) magnetic random access memories in FPGA design. The nonvolatility of the latter is achieved through the use of magnetic tunneling junctions (MTJs) in the MRAM cell. A thermally assisted switching scheme helps to reduce power consumption during write operation in comparison to the writing scheme in the FIMS-MTJ device. Moreover, the nonvolatility of such a design based on either an FIMS or a TAS writing scheme should reduce both power consumption and configuration time required at each power up of the circuit in comparison to classical SRAM-based FPGAs. A real-time reconfigurable (RTR) micro-FPGA using FIMS-MRAM or TAS-MRAM allows dynamic reconfiguration mechanisms, while featuring simple design architecture.

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 REINFORCEMENT LEARNING BASED ANTI-COLLISION ALGORITHM FOR RFID SYSTEMS

2019 ◽  
pp. 155-168
Author(s):  
Murukesan Loganathan ◽  
Thennarasan Sabapathy ◽  
Mohamed Elobaid Elshaikh ◽  
Mohamed Nasrun Osman ◽  
Rosemizi Abd Rahim ◽  
...  
Keyword(s):  
Reinforcement Learning ◽  
Radio Frequency Identification ◽  
Energy Efficient ◽  
Current Standard ◽  
Tag Identification ◽  
Rfid Systems ◽  
Order Of Magnitude ◽  
Control Message ◽  
Frequency Identification ◽  
Better Than

Efficient collision arbitration protocol facilitates fast tag identification in radio frequency identification (RFID) systems. EPCGlobal-Class1-Generation2 (EPC-C1G2) protocol is the current standard for collision arbitration in commercial RFID systems. However, the main drawback of this protocol is that it requires excessive message exchanges between tags and the reader for its operation. This wastes energy of the already resource-constrained RFID readers. Hence, in this work, reinforcement learning based anti-collision protocol (RL-DFSA) is proposed to address the energy efficient collision arbitration problem in the RFID system. The proposed algorithm continuously learns and adapts to the changes in the environment by devising an optimal policy. The proposed RL-DFSA was evaluated through extensive simulations and compared with the variants of EPC-C1G2 algorithms that are currently being used in the commercial readers. Based on the results, it is concluded that RL-DFSA performs equal or better than EPC-C1G2 protocol in delay, throughput and time system efficiency when simulated for sparse and dense environments while requiring one order of magnitude lesser control message exchanges between the reader and the tags.

scholarly journals Магнитостатическая энергия доменных стенок в одноосных пленках конечных размеров

2019 ◽  
Vol 61 (10) ◽  
pp. 1767
Author(s):  
П.М. Ветошко ◽  
Ф.П. Ветошко ◽  
В.Г. Шавров ◽  
В.И. Щеглов
Keyword(s):  
Domain Walls ◽  
Magnetic Sensors ◽  
Magnetization Distribution ◽  
Magnetic Memory ◽  
Spintronic Devices ◽  
Domain Structures ◽  
Magnetic Elements ◽  
Uniform Magnetization ◽  
Equilibrium Configurations ◽  
Equivalent Currents

AbstractThe solution to the problem of calculating the magnetostatic interaction energy of domain walls in uniaxial magnetics with a uniform magnetization distribution inside the domains is given. In carrying out the calculations, the principle of equivalent currents is used, assuming a uniform distribution of magnetization and its representation by equivalent currents flowing along the domain walls and along the surface. Analytical expressions for the mutual induction of two rectangular conductors with an arbitrary aspect ratio have been obtained. Results may be helpful in determining equilibrium configurations of domain structures in magnetic elements of spintronic devices, magnetic sensors and magnetic memory.

Understanding the Magnetic Memory Effect in Fe-Doped NiO Nanoparticles for the Development of Spintronic Devices

2018 ◽  
Vol 2 (1) ◽  
pp. 278-290 ◽  
Author(s):  
Ashish Chhaganlal Gandhi ◽  
R. Pradeep ◽  
Yu-Chen Yeh ◽  
Tai-Yue Li ◽  
Chi-Yuan Wang ◽  
...  
Keyword(s):  
Memory Effect ◽  
Magnetic Memory ◽  
Nio Nanoparticles ◽  
Spintronic Devices

scholarly journals Bioinspired inner microstructured tube controlled capillary rise

2019 ◽  
Vol 116 (26) ◽  
pp. 12704-12709 ◽  
Author(s):  
Chuxin Li ◽  
Haoyu Dai ◽  
Can Gao ◽  
Ting Wang ◽  
Zhichao Dong ◽  
...  
Keyword(s):  
Energy Efficient ◽  
High Speed ◽  
Capillary Rise ◽  
Water Film ◽  
Bulk Water ◽  
External Energy ◽  
Practical Applications ◽  
Agricultural Applications ◽  
Diode Behavior ◽  
Water Elevation

Effective, long-range, and self-propelled water elevation and transport are important in industrial, medical, and agricultural applications. Although research has grown rapidly, existing methods for water film elevation are still limited. Scaling up for practical applications in an energy-efficient way remains a challenge. Inspired by the continuous water cross-boundary transport on the peristome surface ofNepenthes alata, here we demonstrate the use of peristome-mimetic structures for controlled water elevation by bending biomimetic plates into tubes. The fabricated structures have unique advantages beyond those of natural pitcher plants: bulk water diode transport behavior is achieved with a high-speed passing state (several centimeters per second on a milliliter scale) and a gating state as a result of the synergistic effect between peristome-mimetic structures and tube curvature without external energy input. Significantly, on further bending the peristome-mimetic tube into a “candy cane”-shaped pipe, a self-siphon with liquid diode behavior is achieved. Such a transport mechanism should inspire the design of next generation water transport devices.

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