title: Direct Detection of Pure ac Spin Current by X-Ray Pump-Probe Measurements.
abstract: Despite recent progress in spin-current research, the detection of spin current has mostly remained indirect. By synchronizing a microwave waveform with synchrotron x-ray pulses, we use the ferromagnetic resonance of the Py (Ni_{81}Fe_{19}) layer in a Py/Cu/Cu_{75}Mn_{25}/Cu/Co multilayer to pump a pure ac spin current into the Cu_{75}Mn_{25} and Co layers, and then directly probe the spin current within the Cu_{75}Mn_{25} layer and the spin dynamics of the Co layer by x-ray magnetic circular dichroism. This element-resolved pump-probe measurement unambiguously identifies the ac spin current in the Cu_{75}Mn_{25} layer.
authors: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.|Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors: J
authors: J
authors: Li
authors: Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, United Kingdom.
authors: L R
authors: LR
authors: Shelford
authors: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors: P
authors: P
authors: Shafer
authors: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors: A
authors: A
authors: Tan
authors: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors: J X
authors: JX
authors: Deng
authors: Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, United Kingdom.
authors: P S
authors: PS
authors: Keatley
authors: Korea Research Institute of Standards and Science, Yuseong, Daejeon 305-340, Republic of Korea.
authors: C
authors: C
authors: Hwang
authors: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors: E
authors: E
authors: Arenholz
authors: Magnetic Spectroscopy Group, Diamond Light Source, Didcot, Oxfordshire OX11 0DE, United Kingdom.
authors: G
authors: G
authors: van der Laan
authors: Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, United Kingdom.
authors: R J
authors: RJ
authors: Hicken
authors: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors: Z Q
authors: ZQ
authors: Qiu