Evidence for a Kondo Spin Resonance in Magnetic Iron Nanoislands on Antiferromagnetic Chromium Nitride (001)*

We have explored the electronic properties of iron nanoislands on antiferromagnetic chromium nitride substrates [1] using low-temperature (4.2K) scanning tunneling spectroscopy, and we find sharp peaks or V-dips at the Fermi level for the nanoislands which are not seen in plain iron, chromium, or chromium nitride surfaces. Spectra are acquired using both a normal W tip and an Fe-coated W tip, and the spectra show some similarities as well as important differences. The Fermi level peak/dip features can also be mapped spatially using dI/dV conductance mode imaging. Comparisons to theoretical results based on first principles calculations allow us to determine magnetic structural models and compare the observed spectra with the calculated density of states which supports a possible Kondo spin resonance interpretation in terms of a ferromagnetic nanoisland which is magnetically de-coupled from an antiferromagnetic CrN substrate.[2]

[1] K. Alam et al., Physical Review B 96, 104433 (2017).
[2] Manuscript in preparation.