Guan Xiaoyi, Srivastava Saurabh, Thomas Joseph Palathinkal, Heinig Nina F, Kang Jung-Soo, Rahman Md Anisur, Leung Kam Tong
WATLab and Department of Chemistry, University of Waterloo, 200 University Ave. W., Waterloo, Ontario N2L 3G1, Canada.
ACS Appl Mater Interfaces. 2020 Oct 28;12(43):48998-49005. doi: 10.1021/acsami.0c14706. Epub 2020 Oct 16.
As an intermediate form of matter between a single atom or molecule and the bulk, nanoclusters (NCs) provide novel properties because of their high surface area-to-volume ratios and distinct physical and electronic structures. These ultrasmall NCs offer a new approach to advance charge-spin manipulation for novel devices, including spintronics and magnetic tunneling junctions. Here, we deposit monosized ZrO NCs over a large area by using gas-phase aggregation followed by size selection by a quadrupole mass filter. These size-specific NCs exhibit sub-oxide photoemission features at binding energies that are dependent on the cluster size (from 3 to 9 nm), which are attributed to different oxygen vacancy defect states. These dopant-free ZrO NCs also show strongly size-dependent ferromagnetism, which provides distinct advantages in solubility and homogeneity of magnetism when compared to traditional dilute magnetic semiconductors. A defect-band hybridization-induced magnetic polaron model is proposed to explain the origin of this size-dependent ferromagnetism. This work demonstrates a new protocol of magnetization manipulation by size control and promises potential applications based on these defect-rich size-selected NCs.
作为介于单个原子或分子与大块物质之间的中间物质形式，纳米团簇（NCs）因其高的表面积与体积比以及独特的物理和电子结构而具有新颖的性质。这些超小的纳米团簇为包括自旋电子学和磁隧道结在内的新型器件推进电荷 - 自旋操纵提供了一种新方法。在此，我们通过气相聚集在大面积上沉积单尺寸的ZrO纳米团簇，随后通过四极质量过滤器进行尺寸选择。这些特定尺寸的纳米团簇在结合能处表现出亚氧化物光发射特征，该结合能取决于团簇尺寸（从3到9纳米），这归因于不同的氧空位缺陷态。这些无掺杂剂的ZrO纳米团簇还表现出强烈的尺寸依赖性铁磁性，与传统的稀磁半导体相比，这在磁性的溶解性和均匀性方面具有明显优势。提出了一种缺陷带杂化诱导的磁极化子模型来解释这种尺寸依赖性铁磁性的起源。这项工作展示了一种通过尺寸控制进行磁化操纵的新方案，并有望基于这些富含缺陷的尺寸选择纳米团簇实现潜在应用。
