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

Abstract

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 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.

References in corpus (8)

• Theory of spin Hall magnetoresistance
• Negative spin Hall magnetoresistance of Pt on the bulk easy-plane antiferromagnet NiO
• Electrical detection of spiral spin structures in Pt|Cu_2OSeO_3 heterostructures
• Field-free spin-orbit torque switching in Co/Pt/Co multilayer with mixed magnetic anisotropies
• Direct Imaging of Electrical Switching of Antiferromagnetic Néel Order in $\alpha$-Fe${}_2$O${}_3$ Epitaxial Films
• Antiferromagnetic anisotropy determination by spin Hall magnetoresistance
• Exceptional sign changes of the non-local spin Seebeck effect in antiferromagnetic hematite
• Magnetic states at the surface of alpha-Fe2O3 thin films doped with Ti, Zn or Sn