Yang Kai, Paul William, Natterer Fabian D, Lado Jose L, Bae Yujeong, Willke Philip, Choi Taeyoung, Ferrón Alejandro, Fernández-Rossier Joaquín, Heinrich Andreas J, Lutz Christopher P
IBM Almaden Research Center, San Jose, California 95120, USA.
Physik-Institut, University of Zurich, CH-8057 Zurich, Switzerland.
Phys Rev Lett. 2019 Jun 7;122(22):227203. doi: 10.1103/PhysRevLett.122.227203.
Shrinking spintronic devices to the nanoscale ultimately requires localized control of individual atomic magnetic moments. At these length scales, the exchange interaction plays important roles, such as in the stabilization of spin-quantization axes, the production of spin frustration, and creation of magnetic ordering. Here, we demonstrate the precise control of the exchange bias experienced by a single atom on a surface, covering an energy range of 4 orders of magnitude. The exchange interaction is continuously tunable from milli-eV to micro-eV by adjusting the separation between a spin-1/2 atom on a surface and the magnetic tip of a scanning tunneling microscope. We seamlessly combine inelastic electron tunneling spectroscopy and electron spin resonance to map out the different energy scales. This control of exchange bias over a wide span of energies provides versatile control of spin states, with applications ranging from precise tuning of quantum state properties, to strong exchange bias for local spin doping. In addition, we show that a time-varying exchange interaction generates a localized ac magnetic field that resonantly drives the surface spin. The static and dynamic control of the exchange interaction at the atomic scale provides a new tool to tune the quantum states of coupled-spin systems.
将自旋电子器件缩小到纳米尺度最终需要对单个原子磁矩进行局部控制。在这些长度尺度下，交换相互作用起着重要作用，例如在自旋量子化轴的稳定、自旋挫折的产生以及磁有序的形成中。在这里，我们展示了对表面单个原子所经历的交换偏置的精确控制，涵盖了4个数量级的能量范围。通过调整表面上的自旋1/2原子与扫描隧道显微镜的磁性尖端之间的间距，交换相互作用可以从毫电子伏特连续调节到微电子伏特。我们无缝结合非弹性电子隧穿光谱和电子自旋共振来描绘出不同的能量尺度。这种在宽能量范围内对交换偏置的控制提供了对自旋态的通用控制，其应用范围从量子态性质的精确调谐到局部自旋掺杂的强交换偏置。此外，我们表明时变交换相互作用会产生一个局部交流磁场，该磁场会共振驱动表面自旋。在原子尺度上对交换相互作用的静态和动态控制为调节耦合自旋系统的量子态提供了一种新工具。
