Li Mengmeng, Wang Xiuyu
Institute of Process Equipment, College of Energy Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, Zhejiang, China.
J Am Chem Soc. 2025 Jan 15;147(2):1732-1739. doi: 10.1021/jacs.4c12978. Epub 2025 Jan 6.
Further miniaturization of magnetic nanomaterials is intrinsically accompanied by a reduction in spin ordered domains, resulting in size-dependent magnetic behaviors. Consequently, a longstanding roadblock in the advancement of nanodevices based on magnetic nanomaterials is the absence of a method to beat the size-dependent limit in nanomagnetism. Here, we discover and exploit a spin-lattice coupling effect in three-dimensional freestanding magnetic nanoparticles to beat the size-dependent limit for the first time. The so-called spin-lattice coupling involves varying spin configuration and exchange constant of spin interactions induced by lattice deformations. We correlate spin-lattice coupling to g-shift and employ two-dimensional magnetic resonance imaging to visualize -factor. As lattice constants decrease (even ∼1%), positive offset of g-shift increases significantly, signaling stronger spin-lattice coupling, which induces a transition from paramagnetism to surperparamagnetism, thereby effectively beating the size-dependent limit.
磁性纳米材料的进一步小型化本质上伴随着自旋有序域的减少，从而导致磁行为的尺寸依赖性。因此，基于磁性纳米材料的纳米器件发展中一个长期存在的障碍是缺乏一种方法来突破纳米磁性中与尺寸相关的限制。在这里，我们首次发现并利用三维独立磁性纳米颗粒中的自旋-晶格耦合效应来突破与尺寸相关的限制。所谓的自旋-晶格耦合涉及由晶格变形引起的自旋相互作用的自旋构型和交换常数的变化。我们将自旋-晶格耦合与g位移相关联，并采用二维磁共振成像来可视化g因子。随着晶格常数减小（甚至约1%），g位移的正偏移显著增加，这表明自旋-晶格耦合更强，从而诱导从顺磁性到超顺磁性的转变，从而有效地突破了与尺寸相关的限制。
