Programmable magnetic field-free manipulation of perpendicular magnetization switching is essential for the development of ultralow-power spintronic devices. However, the magnetization in a centrosymmetric single-layer ferromagnetic film cannot be switched directly by passing an electrical current in itself. Here, we demonstrate a repeatable bulk spin-orbit torque (SOT) switching of the perpendicularly magnetized CoPt alloy single-layer films by introducing a composition gradient in the thickness direction to break the inversion symmetry. Experimental results reveal that the bulk SOT-induced effective field on the domain walls leads to the domain walls motion and magnetization switching. Moreover, magnetic field-free perpendicular magnetization switching caused by SOT and its switching polarity (clockwise or counterclockwise) can be reversibly controlled in the IrMn/Co/Ru/CoPt heterojunctions based on the exchange bias and interlayer exchange coupling. This unique composition gradient approach accompanied with electrically controllable SOT magnetization switching provides a promising strategy to access energy-efficient control of memory and logic devices.

A gold nanoparticle enhanced organic transistor non-volatile memory (ONVM) operated at ultralow voltages of up to À1 V has been achieved by facile room-temperature solution-processed hybrid nanolayer dielectrics. The amorphous ZrTiO x nanolayer dielectrics exhibit a high-k value of 18.9 and a high capacitance of 705 nF cm À2 . With the modification of the octadecylphosphonic acid (ODPA) monolayer, the a-ZrTiO x /ODPA hybrid nanolayer dielectrics exhibit a high capacitance of 514 nF cm À2 and a very low leakage current density of 2 Â 10 À7 A cm À2 . The pentacene transistor-based ONVMs with the a-ZrTiO x /ODPA hybrid nanolayer dielectrics could be operated in operating voltages as low as À1 V. With ultralow operating voltages, ONVMs show high performances, such as high hole mobility (0.3 cm 2 V À1 s À1 ), large memory window (1.5 V), and long charge retention time (4 Â 10 4 s) directly in ambient air. Our results suggest the great potential of low-temperature solution-processed hybrid nanolayer dielectrics for the realization of low-power and high-performance organic electronic devices.

Fully electrical manipulation of magnetism, preferably through spin current, is highly desired to achieve energy-efficient, nonvolatile, and programmable spin logic devices. It is demonstrated in this study that in a single Pt/IrMn/ Co/Ru/CoPt heterojunction, all 16 Boolean logic functions can be realized in a purely electrical way, relying on electrical manipulation of magnetic-fieldfree spin-orbit torque (SOT) switching. By applying current pulses along with two orthogonal directions, the exchange bias between IrMn and Co, and the SOT switching polarity (clockwise or counterclockwise) of perpendicularly magnetized CoPt, can be reversibly controlled, enabling complete spin logic within a single nonvolatile memory. This study makes a significant step towards practical electrical programmable spin logic devices.

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Solution-processed high-k ZrTiOx dielectric films achieve a k value and capacitance of 53 and 467 nF cm−2, and a low leakage current of 4 × 10−8 A cm−2 with polymer modification. High-performance organic thin film transistors with a carrier mobility of 0.58 cm2 V−1 s−1, and a low operating voltage of 6 V were realized with ZrTiOx dielectric films.