Is Semiconducting\nTransition-Metal Dichalcogenide\nSuitable for Spin Pumping?

Spin pumping has been reported on interfaces formed with\nferromagnetic\nmetals and layered transition-metal dichalcogenides (TMDs), as signified\nby enhanced Gilbert damping parameters extracted from magnetodynamics\nmeasurements. However, whether the observed damping enhancement purely\narises from the pumping effect has remained debatable, given that\npossible extrinsic disturbances on the interfaces cannot be excluded\nin most of the experiments. Here, we explore an atomically clean interface\nformed with CoFeB and atomically thin MoSe<sub>2</sub>, achieved by\nan all <i>in situ</i> growth strategy based on molecular\nbeam epitaxy. Taking advantage of ferromagnetic resonance analysis,\nwe find that the Gilbert damping of the CoFeB/MoSe<sub>2</sub> interface\nclosely resembles that of CoFeB/SiO<sub>2</sub>, suggesting the absence\nof spin pumping. With similar findings demonstrated on a few more\nrepresentative interfaces, this work clarifies the unsuitability of\nsemiconducting TMDs for spin pumping and suggests that the observed\ndamping enhancement in the previous reports may be predominantly attributed\nto extrinsic contributions during the experimental process.