Static Magnetic Proximity Effect in Pt Layers on Sputter-Deposited NiFe₂O₄and on Fe of Various Thicknesses Investigated by XRMR

Abstract

The longitudinal spin Seebeck effect is detected in sputter-deposited NiFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> films using Pt as a spin detector and compared with the previously investigated NiFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> films prepared by chemical vapor deposition. Anomalous Nernst effects induced by the magnetic proximity effect (MPE) in Pt can be excluded for the sputter-deposited NiFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> films down to a certain limit, since X-ray resonant magnetic reflectivity measurements show no magnetic response down to a limit of 0.04 μB per Pt atom comparable with the case of the chemically deposited NiFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> films. These differently prepared films have various thicknesses. Therefore, we further studied Pt/Fe reference samples with various Fe thicknesses and could confirm that the MPE is only induced by the interface properties of the magnetic material.