Thickness-Dependent Electronic Structure Modulation Of Ferromagnetic Films On Shape Memory Alloy Substrates Based On A Pure Strain Effect

Pure strain-induced electronic structure modulation in ferromagnetic films is critical for developing reliable strain-assisted spintronic devices with low power consumption. For the conventional electricity-controlled strain engineering, it is difficult to reveal the pure strain effect on electronic structure tunability due to the inseparability of pure strain effect and surface charge effect. Here, a non-electrically controlled NiTi shape memory alloy was utilized as a strain output substrate to induce a pure strain on attached Fe films through a thermally controlled shape memory effect. The pure strain induced electronic structure evolution was revealed by in-situ X-ray photoelectron spectroscopy and correlated with first-principles calculations and magnetic anisotropy measurements. A compressive strain enhances the shielding effect for core electrons and significantly tunes their binding energy. Meanwhile, the strain modifies the partial density of states of outer d orbits, which may affect spin-orbit coupling strength and related magnetic anisotropy. This work helps for clarifying the physical nature of the pure strain effect and developing the pure-strain-assisted spintronic devices. Published by AIP Publishing.