Spin Logic Devices via Electric Field Controlled Magnetization Reversal by Spin-Orbit Torque

Meiyin Yang,Kaiming Cai,Kaiyou Wang,Yongcheng Deng,Yucai Li,Yan Cui,Kevin William Edmonds,Zhenhua Wu,Sumei Wang,Jun Luo,Yu Sheng,Hou-Zhi Zheng,Yang Ji

doi:10.1109/led.2019.2932479

Abstract

We describe a spin logic device with controllable magnetization switching of perpendicularly magnetized ferromagnet/heavy metal structures on a ferroelectric (1- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${x}$ </tex-math></inline-formula> ) [Pb(Mg 1/3 Nb 2/3 )O 3 ]- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">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.

Highlights

We describe a spin logic device with controllable magnetization switching of perpendicularly magnetized ferromagnet / heavy metal structures on a ferroelectric (1-x)[Pb(Mg1/3Nb2/3)O3]-x[PbTiO3] (PMN-PT) substrate using current-induced spin-orbit torque
By applying voltage pulses to the PMN-PT and current pulses to the heavy metal/ferromagnet device, we demonstrate multiple logic functions using a single magnetic unit
The ferroelectric simulation was done by the technology computer aided design (TCAD) software using the package of global TCAD solutions (GTS)

Summary

EXPERIMENTS

Pt (3 nm)/Co (0.9 nm)/AlOx (2 nm) films were deposited on top of (001)-oriented PMN-PT ferroelectric substrates with thickness of 0.5 mm by magnetron sputtering at room temperature. It requires larger voltage to reverse the deterministic switching loop, and only partial reversal is achieved. To explain this phenomenon, we conducted the ferroelectric hysteresis loop simulation as is shown in Fig. (c). Due to the surface local electrodes on the bulk PMN-PT substrate, the devices are operated at the minor zone so that the magnetization loop exhibits asymmetric between 10 V and -30 V voltages on the PMN-PT substrate. The asymmetric behaviors could be improved by using patterned ferroelectric thin film with low coercivity field in future.

Basic magnetic properties

The Logic functions

The features of the new logic scheme