The rapid increase in information in the big-data era calls for changes to information-processing paradigms, which, in turn, demand new circuit-building blocks to overcome the decreasing cost-effectiveness of transistor scaling and the intrinsic inefficiency of using transistors in non-von Neumann computing architectures. Accordingly, resistive switching materials (RSMs) based on different physical principles have emerged for memories that could enable energy-efficient and area-efficient in-memory computing. In this Review, we survey the four physical mechanisms that lead to such resistive switching: redox reactions, phase transitions, spin-polarized tunnelling and ferroelectric polarization. We discuss how these mechanisms equip RSMs with desirable properties for representation capability, switching speed and energy, reliability and device density. These properties are the key enablers of processing-in-memory platforms, with applications ranging from neuromorphic computing and general-purpose memcomputing to cybersecurity. Finally, we examine the device requirements for such systems based on RSMs and provide suggestions to address challenges in materials engineering, device optimization, system integration and algorithm design. Resistive switching materials enable novel, in-memory information processing, which may resolve the von Neumann bottleneck. This Review focuses on how the switching mechanisms and the resultant electrical properties lead to various computing applications.

Resistive switching materials for information processing

We review the recent developments in the electric field control of magnetism in multiferroic heterostructures, which consist of heterogeneous materials systems where a magnetoelectric coupling is engineered between magnetic and ferroelectric components. The magnetoelectric coupling in these composite systems is interfacial in origin, and can arise from elastic strain, charge, and exchange bias interactions, with different characteristic responses and functionalities. Moreover, charge transport phenomena in multiferroic heterostructures, where both magnetic and ferroelectric order parameters are used to control charge transport, suggest new possibilities to control the conduction paths of the electron spin, with potential for device applications.

https://iopscience.iop.org/article/10.1088/0953-8984/24/33/333201/pdf

Electric field control of magnetism in multiferroic heterostructures

Multiferroic bismuth ferrite-based materials for multifunctional applications: Ceramic bulks, thin films and nanostructures

Spintronic devices exploit the spin, as well as the charge, of electrons and could bring new capabilities to the microelectronics industry However, in order for spintronic devices to meet the ever-increasing demands of the industry, innovation in terms of materials, processes and circuits are required Here, we review recent developments in spintronics that could soon have an impact on the microelectronics and information technology industry We highlight and explore four key areas: magnetic memories, magnetic sensors, radio-frequency and microwave devices, and logic and non-Boolean devices We also discuss the challenges—at both the device and the system level—that need be addressed in order to integrate spintronic materials and functionalities into mainstream microelectronic platforms This Review Article examines the potential of spintronics in four key areas of application —memories, sensors, microwave devices, and logic devices — and discusses the challenges that need be addressed in order to integrate spintronic materials and functionalities into mainstream microelectronic platforms

Opportunities and challenges for spintronics in the microelectronics industry

https://iopscience.iop.org/article/10.1088/0022-3727/49/42/423001/pdf

Magnetic skyrmions: from fundamental to applications

Magnetic and magnetoelectric studies in pure and cation doped BiFeO3

We have investigated the effect of an ultra-thin Ta insertion in the CoFeB (CoFeB/Ta/CoFeB) free layer (FL) on magnetic and tunneling magnetoresistance (TMR) properties of a CoFeB-MgO system with perpendicular magnetic anisotropy (PMA). It is found that the critical thickness (tc) to sustain PMA is doubled (tc = 2.6 nm) in Ta-inserted CoFeB FL as compared to single CoFeB layer (tc = 1.3 nm). While the effective magnetic anisotropy is found to increase with Ta insertion, the saturation magnetization showed a slight reduction. As the CoFeB thickness increasing, the thermal stability of Ta inserted structure is significantly increased by a factor of 2.5 for total CoFeB thickness less than 2 nm. We have observed a reasonable value of TMR for a much thicker CoFeB FL (thickness = 2-2.6 nm) with Ta insertion, and without significant increment in resistance-area product. Our results reveal that an ultra-thin Ta insertion in CoFeB might pay the way towards developing the high-density memory devices with enhanced t...

Thick CoFeB with perpendicular magnetic anisotropy in CoFeB-MgO based magnetic tunnel junction

We have investigated the electric field effects in low resistance perpendicular magnetic tunnel junction (MTJ) devices and found that the electric field can effectively reduce the coercivity (Hc) of free layer (FL) by 30% for a bias voltage Vb = −0.2 V. In addition, the bias field (Hb) on free layer is almost linearly dependent on Vb yet independent on the device size. The demonstrated Vb dependences of Hc and Hb in low resistance MTJ devices present the potential to extend the scalability of the electric field assisted spin transfer torque magnetic random access memory and improve its access speed.

Electric field effects in low resistance CoFeB-MgO magnetic tunnel junctions with perpendicular anisotropy

We report magnetocaloric effect in polycrystalline La0.7−xPrxCa0.3MnO3 (x = 0.0, 0.25, 0.3, 0.35, 0.4, and 0.45) samples. The magnetic entropy change (ΔSm) was measured using a differential scanning calorimeter (DSC) working in a magnetic field environment. The ΔSm shows a peak around the ferromagnetic Curie temperature (TC), and the magnitude of the peak decreases with increasing x (ΔSm = 8.15, 7.27, 6.92, 6.73, 6.41, and 5.84 Jkg−1K−1 for x = 0, 0.25, 0.3, 0.35, 0.4, and 0.45, respectively, for a field change of ΔH = 5 T). We have studied electrical, magnetoresistance, and magnetic properties of x = 0.35 compound in detail. The paramagnetic-ferromagnetic transition in this compound is found to be first order in nature. Magnetization isotherms show a field-induced metamagnetic transition in the paramagnetic (PM) state, and it is accompanied by a change in latent heat, as evidenced by the DSC data. Magnetization data give ΔSm = −7.09 Jkg−1K−1 at T = 190 K and a relative cooling power of 306.5 Jkg−1 for ΔH...

Large reversible magnetocaloric effect in La0.7-xPrxCa0.3MnO3

We demonstrate the manufacturable 22nm FD-SOI 40Mb embedded MRAM (eMRAM), by achieving product functionality and reliability at package level across industrial-grade operating temperature range (−40 to 125 °C) with ECC-off mode. The magnetic tunnel junction stack, integration and etch processes were optimized to achieve superior MTJ performances to meet all product requirements. From package level data, we confirmed the product reliability by passing LTOL, HTOL, 1M endurance cycling and 5x solder reflows tests with failure rate < 1 ppm. In addition, we demonstrate the eMRAM capability to cover stand-by magnetic immunity of ~ 600 Oe at 105 °C for 10 years and active-mode magnetic immunity of ~500 Oe.

Vinayak Bharat Naik

Papers

Magnetic and magnetoelectric studies in pure and cation doped BiFeO3

Thick CoFeB with perpendicular magnetic anisotropy in CoFeB-MgO based magnetic tunnel junction

Electric field effects in low resistance CoFeB-MgO magnetic tunnel junctions with perpendicular anisotropy

Large reversible magnetocaloric effect in La0.7-xPrxCa0.3MnO3

Manufacturable 22nm FD-SOI Embedded MRAM Technology for Industrial-grade MCU and IOT Applications