We describe a spin logic device with controllable magnetization switching of perpendicularly magnetized ferromagnet/heavy metal structures on a ferroelectric (1- ${x}$ ) [Pb(Mg _1/3 Nb _2/3 )O ₃ ]- x [PbTiO3] (PMN-PT) substrate using current-induced spin-orbit torque. The devices were operated without an external magnetic field and controlled by voltages as low as 10 V applied across the PMN-PT substrate, which is much lower compared with the previous reports (500 V). The deterministic switching with smaller voltage was realized from the virgin state of the PMN-PT. The ferroelectric simulation shows the unsaturated minor loop exhibits obvious asymmetries in the polarizations. Larger polarization can be induced from the initial ferroelectric state, while it is difficult for opposite polarization. The XNOR, AND, NAND, and NOT logic functions were demonstrated by the deterministic magnetization switching from the interaction between the spin-orbit torque and electric field at the PMN-PT/Pt interface. The nonvolatile spin logic scheme in this letter is simple, scalable, and programmable, which are favorable in the logic-in-memory design with low energy consumption.

Magnetoresistive random access memory (MRAM) is a promising non-volatile memory technology that can be utilized as an energy and space-efficient storage and computing solution, particularly in cache functions within circuits. Although MRAM has achieved mass production, its manufacturing process still remains challenging, resulting in only a few semiconductor companies dominating its production. In this review, we delve into the materials, processes, and devices used in MRAM, focusing on both the widely adopted spin transfer torque MRAM and the next-generation spin-orbit torque MRAM. We provide an overview of their operational mechanisms and manufacturing technologies. Furthermore, we outline the major hurdles faced in MRAM manufacturing and propose potential solutions in detail. Then, the applications of MRAM in artificial intelligent hardware are introduced. Finally, we present an outlook on the future development and applications of MRAM.

We propose a field-free magnetic switching method in a perpendicular spin-orbit torque magnetic tunneling junction on a 200 mm wafer. The field-free switching can be achieved by unipolar current pulses via engineering the interlayer exchange coupling in the thin ferromagnetic films. The proposed device can reach a high writing speed of up to 1 ns and work properly at temperature of 100°C. This novel unipolar switching scheme offers an alternative writing approach for spin-orbit torque magnetic random access memory.

We investigate the magnetic and electric transport performance of the spin-orbit torque magnetic tunnel junction (SOT-MTJ) with perpendicular magnetic anisotropy (PMA) by stop-on-MgO etching process. This process etches away the hard mask (HM), synthetic antiferromagnetic layer (SAF) and reference layer (RL) while keeping the MgO barrier layer and free layer (FL) retained. Compared with the SOT-MTJ without stop-on-MgO etching process, the SOT-MTJ with stop-on-MgO etching process exhibits nearly zero offset field ( ${H}_{\text {off}}{)}$ and lower critical switching current density ( ${J}_{c}{)}$ with higher thermal stability factor ( $\Delta {)}$ . Although the magnetic property of the FL underneath the MgO is retained, the switching speed can still reach as fast as 1 ns. Furthermore, the SOT-MTJ with stop-on-MgO etching process presents much more concentrated distribution of the statistical coercivity ( ${H}_{c}{)}$ , tunneling magnetoresistance (TMR), ${H}_{\text {off}}$ , $\Delta $ , and ${J}_{c}$ . The resistance-based MTJ yield can raise up to 100%, which is advantageous in the high-speed and large-scale memory application.

We propose and demonstrate a reconfigurable logic gate based on a single spin-orbit torque magnetic tunnel junction (SOT-MTJ) device operated by unipolar voltage inputs. The SOT-MTJ used in the logic can be switched between high and low resistance state when large and small amplitude voltage pulses inject to it. Based on this magnetic switching characteristic, the logic gates of XOR, XNOR and NOT are designed and realized by different amplitude of voltage with the same sign. Compared with spin logics with bipolar current signals as logic inputs, our logic implementation uses much less transistors and significantly simplifies the circuit complexity, which is advantageous for logic-in-memory from the perspective of energy and area efficiency.

Field-free spin–orbit torque switching in synthetic antiferromagnets (SAF) holds significant promise for high-density spintronic memory and logic devices. In this paper, we realize the field-free magnetization switching in SAFs due to the local ion implantation-induced 45° lateral interface and symmetry breaking. Moreover, the magnetization switching ratio is enlarged by the lateral interface owing to the superimposition of a damping-like effective field and a symmetry-breaking effective field. Our work is significant for the development of magnetic random-access memory technology with high-speed and anti-interference ability.