奈米結構內部應用磁域變化機制所導引之電磁致動現象研究

Abstract

在此兩年計畫中，我們提出一個創新的奈米結構應用其内部磁域變化機制所導引之 電磁致動技術，即透過以MEMS/NEMS製程所製作之奈米磁電元件(主要組成:鋯鈦酸鉛 壓電薄膜-單一鎳奈米結構或鎳奈米結構陣列），展示在磁場輔助下以電場控制鎳奈米結 構内部之單一磁域並使磁域翻轉。第一年的設計是使用外部C形電磁鐵以”在晶片外部 (off-chip)”方式對鎳奈米結構之單一磁域產生磁場，促使產生磁場導引之磁域轉變。第 二年的設計是製造鎳奈米結構陣列以”在晶片上(on-chip)”方式對陣列中央之鎳奈米結構 之單一磁域產生磁場，促使產生磁場導引之磁域轉變。每一年之設計在元件產生磁場導 引之磁域轉變後，隨即對元件施加一電場並藉由逆磁電效應來產生一電場導引之磁域轉 變(即對鋯鈦酸鉛薄膜施加電場，藉由壓電效應在薄膜内產生應變，此應變會因鋯鈦酸 鉛薄膜與鎳奈米結構之間的機械耦I合而傳遞至鎳奈米結構，再藉由磁致伸縮效應，此應 變會使鎳奈米結構之單一磁域產生改變）。藉由結合磁場導引之磁域轉變及電場導引之 磁域轉變，單一磁域即能翻轉(磁化方向從0度旋轉至180度），此亦是應用磁場和電場 提供給磁域的總和能量大到足以使磁域翻轉的設計概念。這些預期結果將成為未來奈米 電磁致動技術發展之關鍵基礎。

In this 2-year proposal, we propose our new approaches (i.e., magnetic-domain-engineered nanoscale electromagnetic actuators consisting of either a single-domain Ni-nanobar or geometric-aligned single-domain Ni-nanobar array on top of a piezoelectric PZT thin film) to demonstrate a magnetic-field-assisted electrical control/switching of the magnetic single-domain in the Ni-nanobar. For the 1st year’s approach, we use an external c-shape electromagnet to “off-chip” generate a magnetic field to the single-domain in the Ni-nanobar for demonstrating a magnetic-enhanced domain transformation to the single-domain. For the 2nd year’s approach, we fabricate multiple magnetic nanostructures (i.e., Ni-nanobar array) on PZT-film to “on-chip” generate a magnetic field to the single-domain in the central Ni-nanobar in the array for producing a magnetic-enhanced domain transformation to the single-domain. In each year’s approach, after the magnetic-enhanced domain transformation is produced to the single-domain, we will apply an electric field to the device for producing an electrical-induced domain transformation to the single-domain through the converse magnetoelectric effect (that is, we will apply an electric field to the PZT film to develop in-plane compressive strains in the film through the piezoelectric actuation. Due to mechanical coupling between the PZT-film and Ni-nanobars, the strains are transmitted to the Ni-nanobars. Finally, the strains would transform the single-domain of each Ni-nanobar due to the magnetostriction). By coupling the magnetic-enhanced domain transformation and electrical-induced domain transformation, the single-domain’s magnetization-direction can be switched (i.e., can be rotated from 0-degree to 180-degree). That is, energy provided by the magnetic and electric fields to the single-domain is sufficient to switch the domain’s magnetization-direction. These expected experiment results would be critical advancements for future nanoscale electromagnetic actuators. For more details, we will present design concept, modeling/simulation, fabrication, characterization, and initial results in the proposal.