Antiferromagnetic Spin Coupling between Rare Earth Adatoms and Iron Islands Probed by Spin-Polarized Tunneling.

David Coffey,David Serrate,César De La Fuente,Miguel Ciria,José Ignacio Arnaudas,José Luis Diez-Ferrer

doi:10.1038/srep13709

Abstract

High-density magnetic storage or quantum computing could be achieved using small magnets with large magnetic anisotropy, a requirement that rare-earth iron alloys fulfill in bulk. This compelling property demands a thorough investigation of the magnetism in low dimensional rare-earth iron structures. Here, we report on the magnetic coupling between 4f single atoms and a 3d magnetic nanoisland. Thulium and lutetium adatoms deposited on iron monolayer islands pseudomorphically grown on W(110) have been investigated at low temperature with scanning tunneling microscopy and spectroscopy. The spin-polarized current indicates that both kind of adatoms have in-plane magnetic moments, which couple antiferromagnetically with their underlying iron islands. Our first-principles calculations explain the observed behavior, predicting an antiparallel coupling of the induced 5d electrons magnetic moment of the lanthanides with the 3d magnetic moment of iron, as well as their in-plane orientation, and pointing to a non-contribution of 4f electrons to the spin-polarized tunneling processes in rare earths.

Highlights

High-density magnetic storage or quantum computing could be achieved using small magnets with large magnetic anisotropy, a requirement that rare-earth iron alloys fulfill in bulk
For Rare Earth (RE) adatoms on surfaces, excepting the case of Ce, which attracted some early interest associated with Kondo effect[20,21,22], only few other lanthanides: Gd23,24, Ho25 and Tm26 have been recently investigated by using local probe techniques, on occasion combined with X-ray spectroscopy experiments[26,27]
The results that we report on this letter indicate a non-contribution of 4f electrons to the spin-polarized tunneling processes in RE single atoms on metals, and would not expect to observe an inelastic process related to the 4f shell, suggesting that the inelastic scanning tunneling spectroscopy (IETS) spectra might have a different origin, which supports the conclusions of the above mentioned X-ray experiments

Summary

Introduction

High-density magnetic storage or quantum computing could be achieved using small magnets with large magnetic anisotropy, a requirement that rare-earth iron alloys fulfill in bulk. In a recent paper[27], XAS and XMCD experiments have shown that the ground state of Ho is incompatible with long spin relaxation times, which contradicts the IETS results In this regard, the results that we report on this letter indicate a non-contribution of 4f electrons to the spin-polarized tunneling processes in RE single atoms on metals, and would not expect to observe an inelastic process related to the 4f shell, suggesting that the IETS spectra might have a different origin, which supports the conclusions of the above mentioned X-ray experiments

Methods

Results

Conclusion