Low Power Logic Operations through Pure Spin Currents

基于自旋的电子学概念已经发展到一个阶段，它正在使先进科学和高效率技术发生变革，如磁阻场传感器、硬盘驱动器和磁性随机存取存储器。自旋是每个电子固有的量子特性，它已经在每个电子设备中流动，但很少被捕获。通过将自旋自由度结合到现有的电子设备中，例如中央处理单元（CPU），与目前基于电荷的技术相比，它们可以获得新的功能。此外，现代半导体电子器件已经达到时钟频率的瓶颈，主要是因为只能实现有限的散热。例如，英特尔CPU在十年前达到了3GHz的速度，但由于大约4GHz的散热限制，从那时起（在使用多核解决方案时）一直停滞在这个水平。这被称为“功率墙”-现代CPU处理能力的定义限制。相反，自旋电子器件固有地不受这个问题的影响，即，它们不会因扩散性质而产生焦耳热。因此，用纯自旋电流驱动的器件提供比传统电子器件低得多的功耗;然而，自旋电子器件提出了其他技术挑战。有限的自旋转移效率进入和穿过通道是最重要的，通过各种介质和界面的自旋输运过程的基本理解是进一步开发这些设备的关键。

The concept of spin-based electronics has reached a stage where it is making transformational changes in advanced science and high-efficiency technology, such as magnetoresistance field sensors, hard disk drive and magnetic random access memory. A spin is an innate quantum property of every electron, and it is already flowing within every electronic device but rarely harvested. By incorporating the spin degree of freedom into existing electronic devices such as central processing units (CPUs), they can gain novel functionalities compared to the present charge-based technologies. Furthermore, modern semiconductor electronics have reached a bottleneck in clock frequency, mainly because only limited heat dissipation is achievable. For example, Intel CPUs reached 3GHz speed a decade ago, yet has been stalled at this level ever since (while using multicore solutions) due to the thermal dissipation limits at about 4GHz. This is termed the “power wall” — the defining limit to modern CPU processing power. In contrast, spintronic devices are inherently immune to this issue, i.e., they do not create Joule heating from the diffusive nature. Therefore, devices driven with pure spin currents offer far reduced power consumption than conventional electronic devices; however, spintronic devices present other technological challenges. The limited spin transfer efficiency into and across the channels is the most important, and a fundamental understanding of the spin transport processes through various media and interfaces is critical for further developing these devices.