Electron spin for classical information processing: a brief survey of spin-based logic devices, gates and circuits

Abstract

In electronics, information has been traditionally stored, processed and communicated using an electron's charge. This paradigm is increasingly turning out to be energy-inefficient, because movement of charge within an information processing device invariably causes current flow and an associated dissipation. Replacing 'charge' with the 'spin' of an electron to encode information may eliminate much of this dissipation and lead to more energy-efficient 'green electronics'. This realization has spurred significant research in spintronic devices and circuits where spin either directly acts as the physical variable for hosting information or augments the role of charge. In this review article, we discuss and elucidate some of these ideas, and highlight their strengths and weaknesses. Many of them can potentially reduce energy dissipation significantly, but unfortunately are error-prone and unreliable. Moreover, there are serious obstacles to their technological implementation that may be difficult to overcome in the near term. This review addresses three constructs: (1) single devices or binary switches that can be constituents of Boolean logic gates for digital information processing, (2) complete gates that are capable of performing specific Boolean logic operations, and (3) combinational circuits or architectures (equivalent to many gates working in unison) that are capable of performing universal computation.

Information Processing with Electron Spins

“…There are two types of errors: static fault due to such things as manufacturing defects (e.g., magnet misalignment) [105] and dynamic faults occurring due to erratic magnetization dynamics caused by thermal noise. The latter is usually more serious.…”

Micromagnetic modeling of domain wall motion in sub-100-nm-wide wires with individual and periodic edge defects

“…[1][2][3][4] The logical state of the device depends on the position of a DW, which can be read back using, for example, a magnetic tunnel junction (MTJ), as shown in the elementary logic gate of Fig. 1(a).…”

Spin current generator based on topological insulator coupled to ferromagnetic insulators

“…Spintronic devices [1][2][3][4] operate based on the manipulation of electron spin orientation and transport by magnetic or electrical fields, so as to provide enhanced functionality over conventional electronic devices. Spintronic applications have been proposed or realized in a variety of materials, ranging from ferromagnetic metals, 5 semiconductors, 6 quantum dots, 7 graphene, 8,9 and more recently, topological insulators (TI's).…”