Raman Spectroscopy and Aging of the Low-Loss Ferrimagnet Vanadium Tetracyanoethylene
Raman Spectroscopy and Aging of the Low-Loss Ferrimagnet Vanadium Tetracyanoethylene
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DOI：
10.1021/acs.jpcc.1c04582
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发表时间：
2021-01
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影响因子：
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通讯作者：
H. Cheung;M. Chilcote;H. Yusuf;D. S. Cormode;Yueguang Shi;S. Kurfman;Andrew Franson;M. Flatté;E. Johnston-Halperin;G. Fuchs
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作者：
H. Cheung;M. Chilcote;H. Yusuf;D. S. Cormode;Yueguang Shi;S. Kurfman;Andrew Franson;M. Flatté;E. Johnston-Halperin;G. Fuchs
H. F. H. Cheung，M.奇尔科特湾优素福，D. S. Cormode，Y.施，M. E. Flatté，E. Johnston-Halperin和G. D. Fuchs 4，University of Applied and Engineering Physics，Cornell University，Ithaca，NY 14853，USA Department of Physics，The俄亥俄州州立大学，哥伦布，俄亥俄州43210，USA Department of Physics and Astronomy，University of爱荷华州，爱荷华州City，爱荷华州52242，USA Kavli Institute at Cornell for Nanoscale Science，Ithaca，纽约14853，USA Vanatetracyanoethylene（V[TCNE]x，x <$2）是一种有机基亚铁磁体，具有高磁有序温度TC > 600 K、低磁阻尼和与各种衬底的生长相容性。然而，与其他有机基材料类似，它对空气敏感。虽然用玻璃和环氧树脂封装V[TCNE]x可以将薄膜寿命从一小时延长到几周，但限制其寿命的因素仍然知之甚少。在这里，我们表征封装的V[TCNE]x薄膜使用共聚焦显微镜，拉曼光谱，铁磁共振和SQUID磁强计。我们确定的拉曼光谱中的相关功能与从头算理论一致，再现C = C，C <$N振动模式。我们关联的有效动态磁化强度的变化与拉曼强度和光致发光的变化。基于拉曼光谱的变化，我们推测可能的结构变化和老化机制的V[TCNE]x。这些研究结果使本地光学探头的V[TCNE]x薄膜质量，这是非常宝贵的实验中，评估薄膜质量与当地的磁特性是不可能的。
H. F. H. Cheung, M. Chilcote, H. Yusuf, D. S. Cormode, Y. Shi, M. E. Flatté, E. Johnston-Halperin, and G. D. Fuchs 4, ∗ School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA Vanadium tetracyanoethylene (V[TCNE]x, x ≈ 2) is an organic-based ferrimagnet with a high magnetic ordering temperature TC > 600 K, low magnetic damping, and growth compatibility with a wide variety of substrates. However, similar to other organic-based materials, it is sensitive to air. Although encapsulation of V[TCNE]x with glass and epoxy extends the film lifetime from an hour to a few weeks, what is limiting its lifetime remains poorly understood. Here we characterize encapsulated V[TCNE]x films using confocal microscopy, Raman spectroscopy, ferromagnetic resonance and SQUID magnetometry. We identify the relevant features in the Raman spectra in agreement with ab initio theory, reproducing C = C,C ≡ N vibrational modes. We correlate changes in the effective dynamic magnetization with changes in Raman intensity and in photoluminescence. Based on changes in Raman spectra, we hypothesize possible structural changes and aging mechanisms in V[TCNE]x. These findings enable a local optical probe of V[TCNE]x film quality, which is invaluable in experiments where assessing film quality with local magnetic characterization is not possible.