Samantha Harvey, Jonathan M. DeStefano, Jiun-Haw Chu, Daniel R. Gamelin, Brandi M. Cossairt
{"title":"了解具有室温强磁环二色性的胶体铁磁性 CuCr2Se4 纳米晶体的形成过程","authors":"Samantha Harvey, Jonathan M. DeStefano, Jiun-Haw Chu, Daniel R. Gamelin, Brandi M. Cossairt","doi":"10.1021/acs.chemmater.4c02365","DOIUrl":null,"url":null,"abstract":"The ongoing development and eventual implementation of magnetic nanocrystals in devices requires not only syntheses that can bring bulk compositions down to the nanoscale but also a deep understanding of their formation such that size, morphology, and composition can be finely tuned. Chromium chalcogenide spinels are a class of materials that epitomize this dilemma; their unique magnetic and magneto-optical properties make them promising for applications in spintronics, data storage, and quantum information sciences, but only a few compositions have been synthesized as colloidal nanocrystals. Furthermore, these few existing reports lack mechanistic understanding and demonstrate little control over the physical characteristics of the final products. Here, we set forth to understand the synthesis of CuCr<sub>2</sub>Se<sub>4</sub> nanocrystals by examining how the structure, composition, and magnetic properties evolve over the course of the reaction. We find that the material proceeds through binary copper selenide nanocrystal intermediates followed by Cr incorporation via diffusion. This process results in polycrystalline CuCr<sub>2</sub>Se<sub>4</sub> nanocrystals that do not exhibit magnetic ordering until Cu incorporation modifies their stoichiometry and defects are annealed, which takes approximately 40 min at 340 °C to achieve. The resulting CuCr<sub>2</sub>Se<sub>4</sub> nanocrystals show a strongly enhanced magnetic circular dichroism signal at the bulk plasma frequency of <i>ℏ</i>ω<sub>pl</sub> ∼ 1.0 eV with a field dependence that reflects magnetization of the Cr<sup>3+</sup> spin sublattice. These results highlight the possibility of solution processing strong near-IR magneto-optical materials for future device integration.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":null,"pages":null},"PeriodicalIF":7.2000,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Understanding the Formation of Colloidal Ferrimagnetic CuCr2Se4 Nanocrystals with Strong Room-Temperature Magnetic Circular Dichroism\",\"authors\":\"Samantha Harvey, Jonathan M. DeStefano, Jiun-Haw Chu, Daniel R. Gamelin, Brandi M. Cossairt\",\"doi\":\"10.1021/acs.chemmater.4c02365\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The ongoing development and eventual implementation of magnetic nanocrystals in devices requires not only syntheses that can bring bulk compositions down to the nanoscale but also a deep understanding of their formation such that size, morphology, and composition can be finely tuned. Chromium chalcogenide spinels are a class of materials that epitomize this dilemma; their unique magnetic and magneto-optical properties make them promising for applications in spintronics, data storage, and quantum information sciences, but only a few compositions have been synthesized as colloidal nanocrystals. Furthermore, these few existing reports lack mechanistic understanding and demonstrate little control over the physical characteristics of the final products. Here, we set forth to understand the synthesis of CuCr<sub>2</sub>Se<sub>4</sub> nanocrystals by examining how the structure, composition, and magnetic properties evolve over the course of the reaction. We find that the material proceeds through binary copper selenide nanocrystal intermediates followed by Cr incorporation via diffusion. This process results in polycrystalline CuCr<sub>2</sub>Se<sub>4</sub> nanocrystals that do not exhibit magnetic ordering until Cu incorporation modifies their stoichiometry and defects are annealed, which takes approximately 40 min at 340 °C to achieve. The resulting CuCr<sub>2</sub>Se<sub>4</sub> nanocrystals show a strongly enhanced magnetic circular dichroism signal at the bulk plasma frequency of <i>ℏ</i>ω<sub>pl</sub> ∼ 1.0 eV with a field dependence that reflects magnetization of the Cr<sup>3+</sup> spin sublattice. These results highlight the possibility of solution processing strong near-IR magneto-optical materials for future device integration.\",\"PeriodicalId\":33,\"journal\":{\"name\":\"Chemistry of Materials\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":7.2000,\"publicationDate\":\"2024-10-18\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Chemistry of Materials\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://doi.org/10.1021/acs.chemmater.4c02365\",\"RegionNum\":2,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemistry of Materials","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1021/acs.chemmater.4c02365","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
Understanding the Formation of Colloidal Ferrimagnetic CuCr2Se4 Nanocrystals with Strong Room-Temperature Magnetic Circular Dichroism
The ongoing development and eventual implementation of magnetic nanocrystals in devices requires not only syntheses that can bring bulk compositions down to the nanoscale but also a deep understanding of their formation such that size, morphology, and composition can be finely tuned. Chromium chalcogenide spinels are a class of materials that epitomize this dilemma; their unique magnetic and magneto-optical properties make them promising for applications in spintronics, data storage, and quantum information sciences, but only a few compositions have been synthesized as colloidal nanocrystals. Furthermore, these few existing reports lack mechanistic understanding and demonstrate little control over the physical characteristics of the final products. Here, we set forth to understand the synthesis of CuCr2Se4 nanocrystals by examining how the structure, composition, and magnetic properties evolve over the course of the reaction. We find that the material proceeds through binary copper selenide nanocrystal intermediates followed by Cr incorporation via diffusion. This process results in polycrystalline CuCr2Se4 nanocrystals that do not exhibit magnetic ordering until Cu incorporation modifies their stoichiometry and defects are annealed, which takes approximately 40 min at 340 °C to achieve. The resulting CuCr2Se4 nanocrystals show a strongly enhanced magnetic circular dichroism signal at the bulk plasma frequency of ℏωpl ∼ 1.0 eV with a field dependence that reflects magnetization of the Cr3+ spin sublattice. These results highlight the possibility of solution processing strong near-IR magneto-optical materials for future device integration.
期刊介绍:
The journal Chemistry of Materials focuses on publishing original research at the intersection of materials science and chemistry. The studies published in the journal involve chemistry as a prominent component and explore topics such as the design, synthesis, characterization, processing, understanding, and application of functional or potentially functional materials. The journal covers various areas of interest, including inorganic and organic solid-state chemistry, nanomaterials, biomaterials, thin films and polymers, and composite/hybrid materials. The journal particularly seeks papers that highlight the creation or development of innovative materials with novel optical, electrical, magnetic, catalytic, or mechanical properties. It is essential that manuscripts on these topics have a primary focus on the chemistry of materials and represent a significant advancement compared to prior research. Before external reviews are sought, submitted manuscripts undergo a review process by a minimum of two editors to ensure their appropriateness for the journal and the presence of sufficient evidence of a significant advance that will be of broad interest to the materials chemistry community.