Probing the spiral magnetic phase in 6 nm textured erbium using polarised neutron reflectometry

Abstract

We characterise the magnetic state of highly-textured, sputter deposited erbium for a film of thickness 6 nm. Using polarised neutron reflectometry it is found the film has a high degree of magnetic disorder, and we present some evidence that the films' local magnetic state is consistent with bulk-like spiral magnetism. This, combined with complementary characterisation techniques, show that thin film erbium is a strong candidate material for incorporation into device structures.

Control of Superconductivity with a Single Ferromagnetic Layer in Niobium/Erbium Bilayers

“…We examined a possible current (heating) dependence of the step-like features using currents ranging from 100 nA up to 1 mA, but found no such evidence and current induced local heating can thus be ruled out. There are no known Nb-Er alloys and in our previous reflectivity work we observed no evidence for intermixing at the interface [33], as Co (see for example [13]).…”

“…Finally, below 18 K a conical c-axis ferromagnetic phase is formed. We have been able to confirm that many of the magnetic states of bulk Er are reproducible in sputter deposited epitaxial thin films, and that these magnetic states can be controlled with either temperature or applied magnetic field [32,33].…”

“…The long-range nature of the RKKY interaction (up to 6th nearest neighbour) means that the reduced atomic coordination at the surfaces makes the spiral ends less robust against external perturbation, which clearly becomes more of an influencing factor for thinner films with a lower volume to surface area ratio [33]. It is, therefore, possible that, under the influence of an externally applied magnetic field, the spiral unwinds more readily at the surfaces and, being unable to overcome the energy barrier to reform the spiral, remains locally in the direction of the applied field.…”

Topologically stable helices in exchange coupled rare-earth/rare-earth multilayer with superspin-glass like ordering

“…However, at higher fields, a more complicated but stable and continuous helical arrangement was observed. In another case, evidence of such stable helices within single layer Er films was shown using PNR 2 .…”

“…hin films composed of rare-earth (RE) metals are known to form a helical antiferromagnetic (AF) structure due to competing magnetoelastic, crystalline anisotropy, and exchange interactions [1][2][3] . These interactions can lead to topologically stable spin configurations, which are virtually indispensable in all-spin-based technology 3 .…”