Insight into the structural and magnetotransport properties of epitaxial alpha-Fe2O3/Pt(111) heterostructures: The role of the reversed layer sequence

We report on the chemical structure and spin Hall magnetoresistance (SMR) in epitaxial α-Fe2O3(hematite)(0001)/Pt(111) bilayers with hematite thicknesses of 6 nm and 15 nm grown by molecular beam epitaxy on a MgO(111) substrate. Unlike previous studies that involved Pt overlayers on hematite, the present hematite films were grown on a stable Pt buffer layer and displayed structural changes as a function of thickness. These structural differences (the presence of a ferrimagnetic phase in the thinner film) significantly affected the magnetotransport properties of the bilayers. We observed a sign change of the SMR from positive to negative when the thickness of hematite increased from 6 nm to 15 nm. For α-Fe2O3(15 nm)/Pt, we demonstrated room-temperature switching of the Néel order with rectangular, nondecaying switching characteristics. Such structures open the way to extending magnetotransport studies to more complex systems with double asymmetric metal/hematite/Pt interfaces.

Methods
Conversion electron Moessbauer spectra (CEMS) were collected for ultrathin hematite films.  Data are the source spectra presented in Fig. 2 of the related article:

Data (text files) are the source CEMS spectra 

Fig_2a_P39_cienkie.txt: Source data to Fig.2a, CEMS spectrum of a 60 Å hematite film.
Fig_2b_P39_grube.txt: Source data to Fig.2b, CEMS spectrum of a 150 Å hematite film..