Facultad de Matemática Astronomía y Física, Universidad Nacional de Córdoba and Instituto de Física Enrique Gaviola (IFEG-CONICET), Ciudad Universitaria, 5000 Córdoba, Argentina.
J Phys Condens Matter. 2011 Sep 28;23(38):386004. doi: 10.1088/0953-8984/23/38/386004. Epub 2011 Sep 8.
We performed Monte Carlo simulations of a bilayer system composed of two thin films, one ferromagnetic (FM) and the other antiferromagnetic (AFM). Two lattice structures for the films were considered: simple cubic and body centered cubic (bcc). We imposed an uncompensated interfacial spin structure in both lattice structures; in particular we emulated an FeF2-FM system in the case of the bcc lattice. Our analysis focused on the incidence of the interfacial strength interactions between the films, J(eb), and the effect of thermal fluctuations on the bias field, H(EB). We first performed Monte Carlo simulations on a microscopic model based on classical Heisenberg spin variables. To analyze the simulation results we also introduced a simplified model that assumes coherent rotation of spins located on the same layer parallel to the interface. We found that, depending on the AFM film anisotropy to exchange ratio, the bias field is controlled either by the intrinsic pinning of a domain wall parallel to the interface or by the stability of the first AFM layer (quasi-domain wall) near the interface.
我们对由两层薄膜组成的双层系统进行了蒙特卡罗模拟，其中一层是铁磁（FM），另一层是反铁磁（AFM）。我们考虑了两种薄膜的晶格结构：简单立方和体心立方（bcc）。我们在两种晶格结构中都施加了未补偿的界面自旋结构；特别是在 bcc 晶格的情况下，我们模拟了 FeF2-FM 系统。我们的分析重点是薄膜之间界面强度相互作用 J(eb)的影响，以及热涨落对偏置场 H(EB)的影响。我们首先在基于经典海森堡自旋变量的微观模型上进行了蒙特卡罗模拟。为了分析模拟结果，我们还引入了一个简化模型，该模型假设位于同一层上的自旋平行于界面进行相干旋转。我们发现，取决于 AFM 薄膜的各向异性与交换比，偏置场要么由平行于界面的畴壁的固有钉扎控制，要么由界面附近第一层 AFM（准畴壁）的稳定性控制。
