Ramos-Guivar Juan A, Tamanaha-Vegas Carlo A, Litterst Fred Jochen, Passamani Edson C
Grupo de Investigación de Nanotecnología Aplicada para Biorremediación Ambiental, Energía, Biomedicina y Agricultura (NANOTECH), Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Av. Venezuela Cdra 34 S/N, Ciudad Universitaria, Lima 15081, Peru.
Institut für Physik der Kondensierten Materie, Technische Universität Braunschweig, 38106 Braunschweig, Germany.
Nanomaterials (Basel). 2021 May 24;11(6):1381. doi: 10.3390/nano11061381.
Magnetic properties of ferromagnetic nanostructures were studied by atomistic simulations following Monte Carlo and Landau-Lifshitz-Gilbert approaches. First, we investigated the influence of particle size and shape on the temperature dependence of magnetization for single cobalt and gadolinium nanoparticles and also in bi-magnetic Co@Gd core-shell nanoparticles with different sizes. The Landau-Lifshitz-Gilbert approach was subsequently applied for inspecting the magnetic hysteresis behavior of 2 and 4 nm Co@Gd core-shell nanoparticles with negative, positive, and zero values of interfacial magnetic exchange. We were able to demonstrate the influence of finite-size effect on the dependence of the Curie temperature of Co and Gd nanoparticles. In the Co@Gd core-shell framework, it was possible to handle the critical temperature of the hybrid system by adjusting the Co core size. In addition, we found an improvement in the coercive field values for a negative interfacial exchange energy and for a different core size, suggesting an exchange spring behavior, while positive and zero values of interfacial exchange constant showed no strong influence on the hysteresis behavior.
通过遵循蒙特卡罗和朗道-里夫希茨-吉尔伯特方法的原子模拟研究了铁磁纳米结构的磁性。首先，我们研究了单钴和钆纳米颗粒以及不同尺寸的双磁性Co@Gd核壳纳米颗粒的粒径和形状对磁化强度温度依赖性的影响。随后，采用朗道-里夫希茨-吉尔伯特方法研究了界面磁交换值为负、正和零的2纳米和4纳米Co@Gd核壳纳米颗粒的磁滞行为。我们能够证明有限尺寸效应对Co和Gd纳米颗粒居里温度依赖性的影响。在Co@Gd核壳结构中，可以通过调整Co核尺寸来控制混合系统的临界温度。此外，我们发现对于负的界面交换能和不同的核尺寸，矫顽场值有所提高，表明存在交换弹簧行为，而界面交换常数的正值和零值对磁滞行为没有强烈影响。
