From Termination Dependent Chemical Sensitivity of Spin Orientation in All-bcc Fe/Co Magnetic Superlattices toward the Concept of an Artificial Surface of a Ferromagnet

Abstract

Adsorption of gases on the surface of all-bcc (Fe/Co) N superlattices drives the in-plane, 90° magnetization rotation of the bulk-like Fe(110) supporting ferromagnet. Both experimental and theoretical results prove that terminating the surface of (Fe/Co) N superlattices either by Co or by Fe switches “ON” or “OFF” the spin orientation sensitivity to adsorption. Results indicate that purely surface limited adsorption processes strongly modify the magnetic anisotropy of the entire (Fe/Co) N superlattice, which acts as a kind of “artificial” surface of the bulky Fe(110) ferromagnet. Such an artificial magnetic surface anisotropy concept not only enhances the surface contribution in classical surface–bulk competition but also provides its additional chemical sensitivity.

Tunable interplay between exchange coupling and uniaxial magnetic anisotropy in epitaxial CoO/Au/Fe trilayers

“…Using wedged ferromagnetic bottom layer of the stack allowed us to control its uniaxial in-plane magnetic anisotropy including both smooth evolution of its strength and the change of its sign. The latter is manifested by the well-known spin reorientation transition (SRT) 31 – 33 , in which at the critical Fe thickness, 90-degree, in-plane switching of the Fe easy axis is observed 34 – 38 . The FM-AFM interaction strength and resulting unidirectional MA were controlled by the non-magnetic (NM) spacer thickness in the wedged Au sublayer.…”

Insight into the Temperature-Dependent Canting of 4f Magnetic Moments from 4f Photoemission

“…The need to precisely control the orientation of magnetic moments and especially their reorientation upon changes of external parameters such as temperature or pressure is essential for the development of novel magnetically active materials − including systems with magnetic frustration. − The directions of the moments are closely related to various properties of materials. ,− Therefore, the orientation of the magnetic moments may act as an efficient tunable parameter for manipulation with magnetic exchange fields in magnetic systems, including interfaces, heterostructures, and multilayer sequences, to control the spin-related properties of carriers in elaborated spintronic devices. ,, In the particular case of lanthanides or rare-earth (RE) based materials, the orientation of the 4f moments may sometimes exhibit a strong temperature dependence. Such a canting of the moments may be caused by the specific parameters of the crystal electric field (CEF); , however, it can also be observed in systems where CEF is not expected to play a role …”

“…However, our data demonstrate that the intensity of the valence spectral features is largely temperature-independent. Thus, we can minimize the contribution of the valence states to the analyzed data by considering the difference in the 7 F peak intensity at two temperatures. In this case, the intensity of the valence states can be subtracted and removed from further analysis.…”