arXiv subjects

E. Madej

Publications and source records attributed to E. Madej.

2 recordsLinked to original sources

arXiv2023

Magnetization reversal in Fe(001) films grown by magnetic field assisted molecular beam epitaxy

We studied the influence of a magnetic field (MF) on epitaxial growth and magnetic properties of Fe(001) films deposited on MgO(001). Thanks to modular sample holders and a specialized manipulator in our multi-chamber ultrahigh vacuum system, the films could be deposited and annealed in an in-plane MF of 100 mT. In situ scanning tunnelling microscopy showed that MF had a strong influence on the film morphology, and, in particular, on the structure of surface steps. The magnetic properties were studied ex situ using magneto-optic Kerr effect (MOKE) magnetometry and microscopy. We showed that the moderate in-plane magnetic field applied during growth has the visible impact on the magnetic properties. The observed angular dependence of the MOKE loops and domain structures were discussed based on a magnetization reversal model. In particular we found that magnetization reversal occurs via 90{\deg} domains and the reversal differs for the no-field and in-field grown samples, in correlation with the film morphology.

cond-mat.mtrl-sci↗

arXiv2023

Insight into the structural and magnetotransport properties of epitaxial heterostructures $\alpha$-Fe$_2$O$_3$-Pt(111): Role of the reversed layer sequence

We report on the chemical structure and spin Hall magnetoresistance (SMR) in epitaxial $\alpha$-Fe$_2$O$_3$(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 $\alpha$-Fe$_2$O$_3$(15 nm)/Pt, we demonstrated room-temperature switching of the N\'eel 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.

cond-mat.mtrl-sci↗