Order–Disorder Transitions Confined at the Interface of [email protected] Core–Shell Nanoparticles: Implications for Magnetic Recording,ACS Applied Nano Materials

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Order–Disorder Transitions Confined at the Interface of [email protected] Core–Shell Nanoparticles: Implications for Magnetic Recording
ACS Applied Nano Materials ( IF 5.3 ) Pub Date : 2020-01-24 , DOI: 10.1021/acsanm.9b02371
Kazuhisa Sato _{1,

2} , Hidehiro Yasuda _{1,

2}

Affiliation

We observed an order–disorder transition confined to the interface of [email protected] core–shell nanoparticles with a Pd core and Co shell. A local ordered region with the L1₀- and L1₂-type ordered structure 2–3 nm in size was formed in a ∼12 nm-sized particle. The local atomic order was only achieved in the narrow temperature range of 573–723 K, where the diffusion length is limited to a short-range comparable to the nearest-neighbor distance of the Co–Pd solid solution. Once the atom migration was activated (T ≥ 773 K), alloying of Co and Pd proceeded rapidly, and the ordered phase disappeared along with the core–shell structure. Namely, the stability of the ordered phase was diffusion controlled. Chemically sensitive atomic-resolution electron microscopy enabled detection of the local atomic order formed in a nanoparticle. Such local atomic order has the potential to enable tuning of the magnetic anisotropy of bimetallic nanomagnets, which may open a new route to realize ultrahigh-density magnetic storage media.

中文翻译：

限制在[受电子邮件保护的]核-壳纳米粒子界面的有序无序过渡：对磁记录的影响

我们观察到有序-无序过渡仅限于[电子邮件保护]核-壳纳米粒子与Pd核和Co壳的界面。在一个约12 nm大小的粒子中形成了一个L1 _0-和L1 ₂型有序结构为2-3 nm的局部有序区域。仅在573–723 K的狭窄温度范围内获得了局部原子序，在该温度范围内，扩散长度被限制在与Co-Pd固溶体的最近邻居距离相当的近距离内。一旦原子迁移被激活（T≥773 K），Co和Pd的合金化迅速进行，有序相随着核-壳结构而消失。即，有序相的稳定性受到扩散控制。化学敏感的原子分辨率电子显微镜能够检测纳米粒子中形成的局部原子序。这种局部原子序有可能使双金属纳米磁体的磁各向异性得以调节，这可能为实现超高密度磁存储介质开辟一条新途径。

更新日期：2020-01-24

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