Current-induced switching in atomic-scale structures

通过电流脉冲，超导原子接触的电导可以在两个明确定义的值之间滞后切换，使接触充当原子尺度的存储器。电导的变化是通过单个原子位置的变化来实现的。这个实验和理论相结合的项目的目标是在原子尺度上了解电迁移，阐明原子存储器的功能，并探索它们在各种条件下在纳米电子电路中的适用性。为此，我们将制作和研究由几种超导和非超导金属制成的电流驱动原子开关，以阐明超导对开关机制的作用。此外，我们将把测量范围扩大到更高的温度，直到室温。在理论方面，我们将通过计算电流感应力来应用和扩展原子尺寸结构中电迁移的微观理论，旨在模拟真实纳米接触的电流诱导原子运动。通过将分子动力学模拟与非平衡、偏流情况下的电子结构和输运研究相结合，我们将确定电流诱导的原子重新配置所需的阈值电流，以及各种金属在开关的两种状态下的原子结构。

By current pulses, the conductance of superconducting atomic contacts can be switched hysteretically between two well-defined values, making the contact act as an atomic-scale memory. The conductance change is realized by the change in position of individual atoms. The goal of this combined experimental and theoretical project is to understand electromigration at the atomic scale, to elucidate the functioning of the atomic memories and to explore their applicability in nanoelectronic circuits under various conditions. To this end, we will fabricate and investigate current-driven atomic switches made from several superconducting and non-superconducting metals to elucidate the role of superconductivity for the switching mechanism. Furthermore we will extend the measurements to higher temperatures up to room temperature. From the theoretical side we will apply and extend the microscopic theory of electromigration in atomic-size structures by calculating current-induced forces, aiming at simulations of current-induced atomic motion for realistic nanocontacts. By combining molecular dynamics simulations with electronic structure and transport studies in the non-equilibrium, current-biased situation, we will determine the required threshold current for current-induced atomic reconfigurations and the atomic structure in the two states of a switch for various metals.