Benini Mattia, Shumilin Andrei, Kabanov Viktor, Rakshit Rajib Kumar, Sahoo Antarjami, Halder Anita, Droghetti Andrea, Cugini Francesco, Solzi Massimo, Bisero Diego, Graziosi Patrizio, Riminucci Alberto, Bergenti Ilaria, Singh Manju, Gnoli Luca, Sanna Samuele, Cinchetti Mirko, Mertelj Tomaz, Sanvito Stefano, Dediu Valentin Alek
Istituto per lo Studio dei Materiali Nanostrutturati - CNR (ISMN-CNR), Via Piero Gobetti 101, Bologna, Italy.
Department of Physics, TU Dortmund University, Otto-Hahn-Straße 4, Dortmund, Germany.
Nat Commun. 2025 Jul 1;16(1):5807. doi: 10.1038/s41467-025-61068-7.
The interplay between Hund's coupling, exchange interaction and magnetic anisotropy is responsible for a multitude of magnetic phases, ranging from conventional ferromagnetism to exotic spin textures. Yet, engineering and fine-tuning a magnetic state remains a major challenge in modern magnetism. We show that the chemisorption of organic molecules over Co thin films offers a tool to transform the films from ferromagnetic to a glassy-type state. This emerges when the correlation length of the random anisotropy field, induced by the π-d molecule/metal hybridization, is comparable to the characteristic exchange length. Such a state is characterized by the collapse of the standard domain structure and the emergence of blurred pseudo-domains intertwined by diffuse and irregular domain walls. The magnetization reversal then involves topological vortex-like structures, which are here predicted and successfully measured by magnetic-force microscopy. At the macroscopic level this new glassy-type state is defined by a giant magnetic hardening and the violation of the magnetization-reversal Rayleigh law. Our work thus shows that the electronic interaction of a standard thin-film magnet with readily available molecules can generate structures with remarkable new magnetic properties, and thus opens a new avenue for the design of tailored-on-demand magnetic composites.
洪德耦合、交换相互作用和磁各向异性之间的相互作用导致了多种磁相，从传统的铁磁性到奇异的自旋纹理。然而，在现代磁学中，设计和微调磁态仍然是一个重大挑战。我们表明，有机分子在钴薄膜上的化学吸附提供了一种将薄膜从铁磁态转变为玻璃态的工具。当由π-d分子/金属杂化诱导的随机各向异性场的相关长度与特征交换长度相当时，这种状态就会出现。这种状态的特征是标准畴结构的崩塌以及由弥散且不规则的畴壁交织而成的模糊伪畴的出现。磁化反转涉及拓扑涡旋状结构，本文通过磁力显微镜对其进行了预测并成功测量。在宏观层面，这种新的玻璃态由巨大的磁硬化和对磁化反转瑞利定律的违背来定义。我们的工作因此表明，标准薄膜磁体与易于获得的分子之间的电子相互作用能够产生具有显著新磁特性的结构，从而为按需定制磁性复合材料的设计开辟了一条新途径。
