EPR study of interlayer interaction in Gd2O3/Fe nanostructure

Abstract

In this work, a nanoscale structure consisting of contacting layers of a metal of the iron subgroup and a rare earth metal oxide (REM) is considered. Such nanostructures have an interesting feature, which is that as a result of the contact of these layers, an increase in the galvanomagnetic, magneto-optical and kinetic properties of ferromagnetic metals are observed. Presumably, the enhancement is due to an increase in the magnetization of these metals, caused by the exchange f - d interaction between the unfilled f- and d-electron shells of the atoms that make up the contacting layers. The aim of this work is to find the possibility of such f - d exchange interaction by the EPR method.

To compose the studied nanostructure, Fe used as it has the strongest magnetic properties in its subgroup. Gd₂O₃ was used as an REM oxide as one of the few oxides giving a significant signal in the EPR region. The Gd₂O₃/Fe nanostructure created by sequential electron-beam deposition of Gd₂O₃ and Fe layers on a sitall substrate. The thickness of the oxide and metal layers was 68 and 112 nm, respectively. EPR spectra were recorded at room temperature on a computerized spectrometer Radiopan 2547 SE / X at the frequency of 9.3 GHz. The set of the obtained spectra was processed using the OriginPro and MatLab programs, which confirmed their compliance with the Lorentz model.

From the experimentally obtained EPR linewidth, the parameter of the exchange f - d interaction is determined under the condition of a number of assumptions. The value of the g-factor is also found. Comparison of the EPR parameters of the spectra of individual layers of Gd₂O₃ and Fe with the spectra of the Gd₂O₃/Fe nanostructure composed of them, including the value of the g factor and the exchange interaction parameter, suggests that the presence of an iron layer affects the EPR spectrum of the REM oxide layer Gd₂O₃. The exchange interaction parameter increases from 985 to 4685 (rel. units), the g-factor decreases from 3.5 to 2.4. The most probable reason for the change in the spectrum is the exchange f - d interaction between atoms with unfilled f- and d-electron shells that are parts of the contacting layers.