Probing magnetic exchange interactions with helium

Christopher Trainer, Chi Ming Yim, Christoph Heil, Liam Farrar, Vladimir Tsurkan, Alois Loidl, Peter Wahl

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Controlling and sensing spin-polarization of electrons forms the basis of spintronics. Here, we report a study of the effect of helium on the spin-polarization of the tunneling current and magnetic contrast in spin-polarized Scanning Tunneling Microscopy. We show that the magnetic contrast in SP-STM images recorded in the presence of helium depends sensitively on the tunneling conditions. From tunneling spectra and their variation across the atomic lattice we establish that the helium can be reversibly ejected from the tunneling junction by the tunneling electrons. The energy of the tunneling electrons required to eject the helium depends on the relative spin-polarization of the tip and sample, making the microscope sensitive to the magnetic exchange interactions. We show that the time-averaged spin polarization of the tunneling current is suppressed in the presence of helium and thereby demonstrate voltage control of the spin polarization of the tunneling current across the tip-sample junction.
Original languageEnglish
Article number166803
Number of pages6
JournalPhysical Review Letters
Issue number16
Early online date12 Oct 2021
Publication statusPublished - 15 Oct 2021


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