Switching characteristics of all spin logic devices based on Co and Permalloy nanomagnet

Abstract

The need for low-power alternatives to digital electronic circuits has aroused the increasing interest in spintronic devices for their potentials to overcome the power and performance limitations of (CMOS). In particular, all spin logic (ASL) technology, which stores information using the magnetization direction of the nano-magnet and communicates using spin current, is generally thought to be a good post-CMOS candidate for possessing capabilities such as nonvolatiliy, high density, low energy dissipation. In this paper, based on nano-magnetic dynamics described by Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation and transport physics of spin injection and spin diffusion, a coupled spin-transport/magneto-dynamics model for ASL is established. Under different channel lengths and applied voltages, the switching characteristics of ASL device comprised of Co and Permalloy (Py) nano-magnets are analyzed by using the coupled spin-transport/magneto-dynamics model. The results indicate that the switch delay, energy dissipation and thermal noise effect of PyASL are lower than those of CoASL. The main reason is that the saturation magnetization of Py is less than that of Co. Under the same applied voltage, the maximal channel length of PyASL is longer than that of CoASL when ASL device can switch accurately. Moreover, the two ASL devices' switching delay can be reduced by reducing channel length or increasing applied voltage, and the energy dissipation can be reduced by reducing channel length or applied voltage, whereas there are no optimized applied voltages to minimize the energy-delay product. In addition, the influences of thermal noise on switching delay and energy dissipation can be improved by lowering channel length, but increasing applied voltage can only improve the influence of thermal noise on switching delay. The above-mentioned conclusions will supply essential guidelines for optimizing the ASL devices' materials and configuration.

Input Interface for all Spin Logic

“…where G is a 4×4 spin conductance matrix, and its detailed expression can be found in [17,18]. The whole spin transport model for ASL device can be developed using spin conductance matrices, as shown in Fig.…”

Proposal for a spin logic device based on magneto‐electric effect and spin Hall effect

“…Therefore, additional hardware structure is needed to continuously convert spin-charge information, which partially counteracts the advantage of spin as a state variable for logic operation. But, fortunately, ASLD does not need extra hardware for implementing spin-charge conversion repeatedly, because spin is used at every stage of information processing, transfer, and storage [8]. Thus, ASLD is relatively simpler than other spintronic devices in structure and has been widely studied in the aspects of device switching mechanism [9][10][11], material and structural optimization [12][13][14][15][16][17][18][19][20][21][22][23], and circuit design [24][25][26].…”

Proposal of a magneto-electric effect assisted all spin logic device

“…Especially, an all-spin logic device (ASLD) does not need extra hardware to implement spin-to-charge conversion repeatedly, because spin is used at every stage of information processing, transfer, and storage [6,7]. Thus, ASLD has been proposed as a potential beyond-CMOS option for future digital logic application, and has been widely studied in many aspects such as device materials [8][9][10][11][12][13], dimensional size [14][15][16] and logic circuits [17][18][19][20].…”