Complementary Lateral‐Spin–Orbit Building Blocks for Programmable Logic and In‐Memory Computing

Abstract

Current-driven switching of nonvolatile spintronic materials and devices based on spin-orbit torques offer fast data processing speed, low power consumption, and unlimited endurance for future information processing applications. Analogous to conventional CMOS technology, it is important to develop a pair of complementary spin-orbit devices with differentiated magnetization switching senses as elementary building blocks for realizing sophisticated logic functionalities.Various attempts using external magnetic field or complicated stack/circuit designs have been proposed, however, plainer and more feasible approaches are still strongly desired. Here we show that a pair of two locally laser annealed perpendicular Pt/Co/Pt devices with opposite laser track configurations and thereby inverse field-free lateral spin-orbit torques (LSOTs) induced switching senses can be adopted as such complementary spin-orbit building blocks. By electrically programming the initial magnetization states (spin down/up) of each sample, four Boolean logic gates of AND, OR, NAND and NOR, as well as a spin-orbit half adder containing an XOR gate, were obtained. Moreover, various initialization-free, working current intensity-programmable stateful logic operations, including material implication (IMP) gate, were also demonstrated by regarding the magnetization state as a logic input. Our complementary LSOT building blocks provide a potentially applicable way towards future efficient spin logics and in-memory computing architectures.

Spin logic operations based on magnetization switching by asymmetric spin current

“…Only when A = B = 0, the overlapped current pulses I ovlp = −2 mA could switch the magnetization from down to up state, the outputs are 1. These logic gates could be used as building blocks for programmable and stateful logic operations [31]. For application, we propose a kind of MTJ, which could be integrated into our structure.…”

Prospect of Spin-Orbitronic Devices and Their Applications

“…The current-induced an out-of-plane effective field and thereby zero-field magnetization switching was then achieved, the switching sense of which depends only on the relative location of the Pt-rich and the Co-rich regions, regardless of the net spin polarization of external spin current from both the bottom and the top Pt layers. The complementary spin-orbit building blocks analog to the n- and p-type semiconductors were then demonstrated by using a pair of lateral SOT devices with opposite laser annealing locations ( Zhang et al., 2020a ).…”

“…Subsequently, the SOC layer is etched to form the two or three terminals device, and the gap filling is to be implemented following with chemical mechanical planarization. Also note that most recently reported SOTs in various single magnetic layers could help to facilitate the development of SOT-MTJs without the SOC layer ( Wang et al., 2012 ; Amin et al., 2019 ; Luo et al., 2019b ; Liu et al., 2020a ; Zhang et al., 2020a ; Tang et al., 2020 ; Cao et al., 2020 ). Eventually, a dual damascene Cu or TiN electrode will be fabricated to complete the electrical connection for routing and testing.…”

All-Electrical Multifunctional Spin Logics by Adjusting the Spin Current Density Gradient in a Single Device

“…As the data-intensive applications in fields including big data and machine learning emerge, conventional microelectronic logic circuits based on complementary metal-oxide semiconductor (CMOS) reach their technological limits. Because these applications require both high-performance and energy-efficient computation, a non-von Neumann computational approach such as in-memory computing and synaptic computing is expected to extend the performance of today’s computers substantially. , Logic-in-memory computing, using the same basic device structure as a hardware architecture for both information processing and storage, is a promising approach for tackling data-intensive and adaptive logic applications. − Spin logic devices have expressed the potential for constructing logic-in-memory computing architectures with high-density information capability and fast operating speed. − Particularly, SOT-based logic devices, due to their unique advantages in programmability, nonvolatility, and integration, have attracted great attention. − Highly efficient current-induced magnetization switching techniques have been achieved in heavy metal/ferromagnet (HM/FM) heterostructures with perpendicular magnetic anisotropy (PMA). − With the symmetry breaking between the magnetization up and down, the transverse spin current exerts torque on the magnetization of the FM layer, leading to the deterministic magnetization switching . Here, the symmetry breaking field can be an external magnetic field, exchange coupling effect, or wedge structure. − However, the switching chirality is difficult to be reversibly controlled by electrical manners in such structures.…”