Key Laboratory of Optoelectronic Technology & Systems, Education Ministry of China, Chongqing University and College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China and School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin 541004, China.
School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin 541004, China.
Nanoscale. 2017 Mar 2;9(9):2992-3001. doi: 10.1039/c6nr07231c.
Ferromagnetic character and biocompatible properties have become key factors for developing next-generation spintronic devices and show potential in biomedical applications. Unfortunately, the Mn-containing monolayer is not biocompatible though it has been extensively studied, and the Cr-containing monolayer is not environmental friendly, although these monolayers are ferromagnetic. Herein, we systematically investigated new types of 2D ferromagnetic monolayers NbX (X = Cl, Br or I) by means of first principles calculations together with mean field approximation based on the classical Heisenberg model. The small cleavage energy and high in-plane stiffness have been calculated to evaluate the feasibility of exfoliating the monolayers from their layered bulk phase. Spin-polarized calculations together with self-consistently determined Hubbard U were utilized to assess a strong correlation energy, which demonstrated that NbX (X = Cl, Br or I) monolayers are ferromagnetic. The calculated Curie temperatures for NbCl, NbBr and NbI were 31, 56 and 87 K, respectively, which may be increased by external strain, or electron or hole doping. Moreover, the NbX (X = Cl, Br or I) monolayers exhibited strong visible and infrared light absorption. The biocompatibility, ferromagnetism and considerable visible and infrared light absorption render the NbX (X = Cl, Br or I) monolayers with great potential application in next-generation biocompatible spintronic and optoelectronic devices.
铁磁性和生物兼容性已经成为开发下一代自旋电子器件的关键因素，并在生物医学应用中显示出了潜力。不幸的是，尽管含锰的单层已经被广泛研究，但它并不具有生物兼容性，而含铬的单层虽然具有铁磁性，但并不环保。在此，我们通过第一性原理计算和基于经典海森堡模型的平均场近似，系统地研究了新型二维铁磁单层 NbX（X=Cl、Br 或 I）。我们计算了小的劈裂能和高的面内刚度，以评估从层状体相剥离单层的可行性。自旋极化计算以及自洽确定的 Hubbard U 被用于评估强相关能量，这表明 NbX（X=Cl、Br 或 I）单层是铁磁的。对于 NbCl、NbBr 和 NbI，计算得到的居里温度分别为 31、56 和 87 K，这些温度可以通过外部应变、电子或空穴掺杂来提高。此外，NbX（X=Cl、Br 或 I）单层表现出强烈的可见光和红外光吸收。NbX（X=Cl、Br 或 I）单层的生物兼容性、铁磁性和可观的可见光和红外光吸收，使得它们在下一代生物兼容的自旋电子学和光电子学器件中有很大的应用潜力。
