Xu Keran, Tang Jiabei, Wang Yanzhe, Zhu Yinning, Geng Liwei D
Department of Materials Science and Engineering, Sichuan University-Pittsburgh Institute, Sichuan University, Chengdu 610065, China.
Materials (Basel). 2023 Aug 18;16(16):5689. doi: 10.3390/ma16165689.
The Co-Pt binary system can form a two-phase nanochessboard structure comprising regularly aligned nanorods of magnetically hard tetragonal L1 phase and magnetically soft cubic L1 phase. This Co-Pt nanochessboard, being an exchange-coupled magnetic nanocomposite, exhibits a strong effect on magnetic domains and coercivity. While the ideal nanochessboard structure has tiles with equal edge lengths (a = b), the non-ideal or nonstandard nanochessboard structure has tiles with unequal edge lengths (a ≠ b). In this study, we employed phase-field modeling and computer simulation to systematically investigate the exchange coupling effect on magnetic properties in nonstandard nanochessboards. The simulations reveal that coercivity is dependent on the length scale, with magnetic hardening occurring below the critical exchange length, followed by magnetic softening above the critical exchange length, similar to the standard nanochessboards. Moreover, the presence of unequal edge lengths induces an anisotropic exchange coupling and shifts the coercivity peak with the length scale.
Co-Pt二元体系可以形成一种两相纳米棋盘结构，该结构由磁性硬的四方L1相和磁性软的立方L1相的规则排列纳米棒组成。这种Co-Pt纳米棋盘作为一种交换耦合磁性纳米复合材料，对磁畴和矫顽力有很强的影响。理想的纳米棋盘结构具有边长相等（a = b）的小块，而非理想或非标准的纳米棋盘结构具有边长不相等（a ≠ b）的小块。在本研究中，我们采用相场建模和计算机模拟来系统地研究非标准纳米棋盘中交换耦合对磁性的影响。模拟结果表明，矫顽力取决于长度尺度，在临界交换长度以下发生磁硬化，在临界交换长度以上发生磁软化，这与标准纳米棋盘类似。此外，边长不相等会引起各向异性交换耦合，并使矫顽力峰值随长度尺度发生偏移。
