Holle Nils, Walfort Sebastian, Mazzarello Riccardo, Salinga Martin
University of Münster, Institute of Materials Physics, Münster, Germany.
Sapienza Universitá di Roma, Department of Physics, Roma, Italy.
Commun Mater. 2025;6(1):56. doi: 10.1038/s43246-025-00776-5. Epub 2025 Mar 29.
Today, devices based on phase change materials (PCMs) are expanding beyond their traditional application in non-volatile memory, emerging as promising components for future neuromorphic computing systems. Despite this maturity, the electronic transport in the amorphous phase is still not fully understood, which holds in particular for the resistance drift. This phenomenon has been linked to physical aging of the glassy state. PCM glasses seem to evolve towards structures with increasing Peierls-like distortions. Here, we provide direct evidence for a link between Peierls-like distortions and local current densities in nanoscale phase change devices. This supports the idea of the evolution of these distortions as a source of resistance drift. Using a combination of density functional theory and non-equilibrium Green's function calculations, we show that electronic transport proceeds by states close to the Fermi level that extend over less distorted atomic environments. We further show that nanoconfinement of a PCM leads to a wealth of phenomena in the atomic and electronic structure as well as electronic transport, which can only be understood when interfaces to confining materials are included in the simulation. Our results therefore highlight the importance and prospects of atomistic-level interface design for the advancement of nanoscaled phase change devices.
如今，基于相变材料（PCM）的器件正从其在非易失性存储器中的传统应用领域向外拓展，成为未来神经形态计算系统中颇具潜力的组件。尽管已发展到这种成熟程度，但非晶相中的电子输运仍未被完全理解，尤其是电阻漂移问题。这种现象与玻璃态的物理老化有关。PCM玻璃似乎会朝着具有越来越多类皮尔斯畸变的结构演化。在此，我们为纳米级相变器件中类皮尔斯畸变与局部电流密度之间的联系提供了直接证据。这支持了将这些畸变的演化视为电阻漂移来源的观点。通过结合密度泛函理论和非平衡格林函数计算，我们表明电子输运是由靠近费米能级且在畸变较小的原子环境中延伸的态进行的。我们还表明，PCM的纳米限域会在原子和电子结构以及电子输运方面引发大量现象，只有在模拟中纳入与限域材料的界面时才能理解这些现象。因此，我们的结果凸显了原子级界面设计对于推进纳米级相变器件的重要性和前景。
