Bending Strain-Tailored Magnetic and Electronic Transport Properties of Reactively Sputtered γ′-Fe₄N/Muscovite Epitaxial Heterostructures toward Flexible Spintronics
2020
Shi, Xiaohui | Wu, Mei | Lai, Zhengxun | Li, Xujing | Gao, Peng | Mi, Wenbo
The strain modulation on the magnetic and electronic transport properties of the ferromagnetic films is one of the hot topics due to the practical applications in flexible and wearable spintronic devices. However, the large strain-induced saturation magnetization and resistance change is not easy to achieve because most of the ferromagnetic films deposited on flexible substrates are polycrystalline or amorphous. Here, the flexible epitaxial γ′-Fe₄N/mica films are fabricated by facing-target reactive sputtering. At a tensile strain with a radius of curvature (ROC) of 3 mm, the saturation magnetization (Mₛ) of the γ′-Fe₄N/mica film is tailored significantly with a maximal variation of 210%. Meanwhile, the magnetic anisotropy was broadly tunable at different strains, where the out-of-plane Mᵣ/Mₛ at a tensile strain of ROC = 2 mm is six times larger than that at the unbent state. Besides, the strain-tailored longitudinal resistance Rₓₓ and anomalous Hall resistivity ρₓy appear where the drop of Rₓₓ (ρₓy) reaches 5% (22%) at a tensile strain of ROC = 3 mm. The shift of the nitrogen position in the γ′-Fe₄N unit cell at different bending strains plays a key role in the strain-tailored magnetic and electronic transport properties. The flexible epitaxial γ′-Fe₄N films have the potential applications in magneto- and electromechanical wearable spintronic devices.
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