Possible Room-Temperature Ferromagnetism in Self-Assembled Ensembles of Paramagnetic and Diamagnetic Molecular Semiconductors

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• 作者：Barun Dhara ; Kartick Tarafder ; Plawan K. Jha ; Soumendra N. Panja ; Sunil Nair ; Peter M. Oppeneer ; Nirmalya Ballav
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：December 15, 2016
• 年：2016
• 卷：7
• 期：24
• 页码：4988-4995
• 全文大小：583K
• ISSN：1948-7185

文摘

Owing to long spin-relaxation time and chemically customizable physical properties, molecule-based semiconductor materials like metal-phthalocyanines offer promising alternatives to conventional dilute magnetic semiconductors/oxides (DMSs/DMOs) to achieve room-temperature (RT) ferromagnetism. However, air-stable molecule-based materials exhibiting both semiconductivity and magnetic-order at RT have so far remained elusive. We present here the concept of supramolecular arrangement to accomplish possibly RT ferromagnetism. Specifically, we observe a clear hysteresis-loop (H_c ≈ 120 Oe) at 300 K in the magnetization versus field (M–H) plot of the self-assembled ensembles of diamagnetic Zn-phthalocyanine having peripheral F atoms (ZnFPc; S = 0) and paramagnetic Fe-phthalocyanine having peripehral H atoms (FePc; S = 1). Tauc plot of the self-assembled FePc···ZnFPc ensembles showed an optical band gap of ∼1.05 eV and temperature-dependent current–voltage (I–V) studies suggest semiconducting characteristics in the material. Using DFT+U quantum-chemical calculations, we reveal the origin of such unusual ferromagnetic exchange-interaction in the supramolecular FePc···ZnFPc system.