Nat Mater. 2011 Jul 3;10(9):660-4. doi: 10.1038/nmat3053.
Spin currents--the flow of angular momentum without the simultaneous transfer of electrical charge--play an enabling role in the field of spintronics. Unlike the charge current, the spin current is not a conservative quantity within the conduction carrier system. This is due to the presence of the spin-orbit interaction that couples the spin of the carriers to angular momentum in the lattice. This spin-lattice coupling acts also as the source of damping in magnetic materials, where the precessing magnetic moment experiences a torque towards its equilibrium orientation; the excess angular momentum in the magnetic subsystem flows into the lattice. Here we show that this flow can be reversed by the three-magnon splitting process and experimentally achieve the enhancement of the spin current emitted by the interacting spin waves. This mechanism triggers angular momentum transfer from the lattice to the magnetic subsystem and modifies the spin-current emission. The finding illustrates the importance of magnon-magnon interactions for developing spin-current based electronics.
自旋电流——角动量的流动而没有电荷的同时传递——在自旋电子学领域中起着重要的作用。与电荷电流不同，自旋电流在传导载流子系统内不是保守量。这是由于自旋轨道相互作用的存在，它将载流子的自旋与晶格中的角动量耦合在一起。这种自旋晶格耦合也充当了磁材料中的阻尼源，其中进动的磁矩受到使其恢复到平衡方向的力矩作用；磁子系统中的多余角动量流入晶格。在这里，我们表明这种流动可以通过三磁子分裂过程反转，并在实验上实现了相互作用的自旋波发射的自旋电流的增强。这种机制触发了角动量从晶格向磁子系统的传递，并改变了自旋电流的发射。这一发现说明了磁子-磁子相互作用对于发展基于自旋电流的电子学的重要性。
