Suppression of Spin Pumping at Metal Interfaces

An electrically conductive metal typically transmits or absorbs a spin current. Here, we report on evidence that interfacing two metal thin films can suppress spin transmission and absorption. We examine spin pumping in ferromagnet/spacer/ferromagnet heterostructures, in which the spacer -- consisting of metallic Cu and Cr thin films -- separates the ferromagnetic spin-source and spin-sink layers. The Cu/Cr spacer largely suppresses spin pumping -- i.e., neither transmitting nor absorbing a significant amount of spin current -- even though Cu or Cr alone transmits a sizable spin current. The antiferromagnetism of Cr is not essential for the suppression of spin pumping, as we observe similar suppression with Cu/V spacers where V is a nonmagnetic analogue of Cr. We speculate that diverse combinations of spin-transparent metals may form interfaces that suppress spin pumping, although the underlying mechanism remains unclear. Our work may stimulate a new perspective on understanding and engineering spin transport in metallic multilayers

Analysis of the environmental magnetic noise rejection by using two simple magnetoelectric sensors

International audienceWe have evaluated the performance of a classical differential technique to reject magnetic or, in a lesser extent, the vibrational coherent noise sources sensed by two identical magnetoelectric (ME) laminated sensors with the help of a data logger. The signals of two ME sensors were directly subtracted given highly homogeneous external noise. Through a signal processing technique, the intrinsic noise of the ME sensor systems was obtained to be 20 pT/√Hz with a rejection factor of the external homogeneous noise sources of 20. The latter is mainly limited, as theoretical described, by the incoherent noise and discrepancy between the sensors. To demonstrate the efficiency of this technique by using ME sensors, internal noise tests were also performed in a magnetic shielding chamber for individual ME sensor and shown to be close to that of the sensors in an open environmen