Ultra-Fast Perpendicular Spin–Orbit Torque MRAM

Abstract

We demonstrate ultra-fast (down to 400 ps) bipolar magnetization switching of a threeterminal perpendicular Ta/FeCoB/MgO/FeCoB magnetic tunnel junction. The critical current density rises significantly as the current pulse shortens below 10 ns, which translates into a minimum in the write energy in the ns range. Our results show that SOT-MRAM allows fast

Energy‐Efficient Ultrafast SOT‐MRAMs Based on Low‐Resistivity Spin Hall Metal Au0.25Pt0.75

“…We have demonstrated switching of prototypical SOT-MRAM structures with 50% probability using I ≈ 3 mA and E write = 2 pJ for 200 ps current pulses, and write error rates <10 −5 at I = 4 mA and E write = 14 pJ for 1 ns pulses. The collinear in-plane MRAMs can be switched directly by spin current from the spin Hall channel, while perpendicular SOT-MTJs require a markedly high write current in the nanosecond and sub-nanosecond pulse regime [16,41] as well as assistance of a strong in-plane magnetic field (e.g., stray field from an adjacent ferromagnetic layer [41,42] or built-in magnetic field from a lateral structural asymmetry [43] ) or an additional large write current in the MTJ nanopillar, [40] which may lower the energy efficiency, the scalability, and the endurance of the MTJ cells. The relatively low channel resistance due to the low ρ xx of Au 0.25 Pt 0.75 is beneficial for decreasing write energies, achieving unlimited endurance, and also for matching the impedance of superconducting circuits in cryogenic computation systems.…”

“…An alternative, 3-terminal spin-orbit torque (SOT) MRAM [8,9] has the potential to mitigate these issues. [7,[14][15][16][17] SOT-MRAMs based on a spin Hall metal that combines a giant spin Hall ratio (θ SH ) with a relatively low resistivity (ρ xx ) can also have unlimited endurance due to the suppression of Joule heating induced bursting and migration of the write line [2] as well as low values of write impedance that is compatible with superconducting circuits in cryogenic computing systems. The nonvolatile SOT-MRAMs can have long data retention, zero standby power, and fast and reliable write.…”

“…While the limited-statistics switching probability for pulse current and duration sweeps (for instance, 1000 events in Figure 2a) are routinely used to report the existence of highspeed switching, [4,16,17] they do not convey the statistics of the write error rate (WER)-information that is critical for applications. While the limited-statistics switching probability for pulse current and duration sweeps (for instance, 1000 events in Figure 2a) are routinely used to report the existence of highspeed switching, [4,16,17] they do not convey the statistics of the write error rate (WER)-information that is critical for applications.…”

High Spin Hall Conductivity in Large‐Area Type‐II Dirac Semimetal PtTe2

“…Spin–orbit torque (SOT) provides an ultrafast and energy‐efficient means to switch magnetization, which is of fundamental and technical importance for spintronic devices. [ 1–5 ] A typical SOT device consists of heavy metal/ferromagnet (HM/FM) bilayer, where the HM (e.g., Pt, W, Ta, etc.) converts charge current into spin current mainly due to the spin Hall effect (SHE) and then exerts a torque on the adjacent FM enabling magnetization manipulation.…”

Enhancing Spin-Orbit Torque by Strong Interfacial Scattering From Ultrathin Insertion Layers

“…Spin-orbit torques (SOTs) generated by the spin Hall effect (SHE) can efficiently switch thin-film nanomagnet devices [1][2][3][4], excite magnetization oscillations [5], and drive skyrmion and chiral domain wall displacement [7,8]. Increasing SOT efficiencies is of great importance for enabling new research into spintronics phenomena [1][2][3][4][5][6][7][8][9] and for advancing technological applications of SOTs [10][11][12][13]. Of particular interest in this effort is to develop heavy metals (HMs) that can simultaneously provide a large damping-like SOT efficiency per current density ( DL ), easy growth, good chemical/thermal stability, and the capability to be readily integrated into complex experimental configurations and/or into manufacturing processes.…”