Schmidt R, Lazo C, Hlscher H, Pi U H, Caciuc V, Schwarz A, Wiesendanger R, Heinze S
Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany.
Nano Lett. 2009 Jan;9(1):200-4. doi: 10.1021/nl802770x.
Applying magnetic exchange force microscopy with an Fe-coated tip, we experimentally resolve the atomic-scale antiferromagnetic structure of the Fe monolayer on W(001). On the basis of first-principles calculations, using an Fe nanocluster as a tip, we determine the distance dependence of the magnetic exchange forces. Significant relaxation of tip and sample atoms occurs, which depend sensitively on the local magnetic configuration. This shifts the onset of magnetic interactions toward larger separations and facilitates their observation. Implementing a multiatom tip in the calculations and accounting for relaxation effects are crucial to obtain the correct sign and distance dependence of the magnetic exchange interaction. By comparison with our calculations, we show that the experimentally observed contrast is due to a competition between chemical and magnetic forces.
我们使用涂有铁的探针进行磁交换力显微镜实验，解析了W(001)上铁单层的原子尺度反铁磁结构。基于第一性原理计算，以铁纳米团簇作为探针，我们确定了磁交换力与距离的关系。探针和样品原子发生了显著弛豫，这对局部磁结构敏感依赖。这使得磁相互作用的起始点向更大间距移动，便于对其进行观测。在计算中采用多原子探针并考虑弛豫效应对于获得磁交换相互作用的正确符号和距离依赖性至关重要。通过与我们的计算结果比较，我们表明实验观察到的对比度是由于化学力和磁力之间的竞争所致。
