Rózsa Levente, Deák András, Simon Eszter, Yanes Rocio, Udvardi László, Szunyogh László, Nowak Ulrich
Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary.
Department of Theoretical Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary.
Phys Rev Lett. 2016 Oct 7;117(15):157205. doi: 10.1103/PhysRevLett.117.157205.
We determined the parameters of a classical spin Hamiltonian describing an Fe monolayer on Pd(111) surface with a Pt_{1-x}Ir_{x} alloy overlayer from ab initio calculations. While the ground state of the system is ferromagnetic for x=0.00, it becomes a spin spiral state as Ir is intermixed into the overlayer. Although the Dzyaloshinsky-Moriya interaction is present in the system, we will demonstrate that the frustrated isotropic exchange interactions play a prominent role in creating the spin spiral state, and these frustrated couplings lead to an attractive interaction between Skyrmions at short distances. Using spin dynamics simulations, we show that under these conditions the individual Skyrmions form clusters, and that these clusters remain stable at finite temperature.
我们通过从头算计算确定了一个描述Pd(111)表面上具有Pt₁₋ₓIrₓ合金覆盖层的Fe单层的经典自旋哈密顿量的参数。当x = 0.00时，系统的基态是铁磁性的，但随着Ir混入覆盖层，它变成了自旋螺旋态。尽管系统中存在Dzyaloshinsky-Moriya相互作用，但我们将证明，受挫的各向同性交换相互作用在产生自旋螺旋态中起主要作用，并且这些受挫耦合导致短距离内斯格明子之间的吸引相互作用。使用自旋动力学模拟，我们表明在这些条件下，单个斯格明子形成簇，并且这些簇在有限温度下保持稳定。
