Flexible magnetic devices are one of the indispensable flexible devices. However, the deformation of the magnetic devices will change the magnetic anisotropy of magnetic materials due to magnetoelastic anisotropy, which will decrease the performance of the devices. Therefore, it is essential to determine the stress-coefficient of magnetoelastic anisotropy in magnetic materials. Here, the magnetic anisotropy constants of an amorphous CoFeB film on a flexible polyvinylidene fluoride (PVDF) substrate in different stress states were quantitatively investigated by anisotropic magnetoresistance (AMR). The enhanced magnetic anisotropy of the CoFeB film at reduced temperature is due to magnetoelastic anisotropy induced by anisotropic thermal expansion of the PVDF substrate. Through fitting the AMR curves under variant fields in different stress states, the stress-coefficient of magnetoelastic anisotropy in the amorphous CoFeB film is obtained to be 170.7 × 103 erg cm−3 GPa−1.

Spin valve devices, consisting of a free magnetic layer, a spacer layer, and a pinned magnetic layer, are widely used in magnetic sensors and nonvolatile magnetic memories. However, even a slight bending deformation can affect the magnetization direction of the free magnetic layer, which will change the magnetoresistance signal of the devices. Therefore, it is a challenge to develop a flexible spin valve device with controllable performance. Here, an enhanced stress-invariance of the magnetization direction in amorphous CoFeB magnetic films on flexible polyimide substrates is achieved. The uniaxial anisotropy is induced by growing on the bent substrate under a magnetic field, which aligns more magnetic domains with easy axes along the direction perpendicular to the subsequently applied stress. Theoretical calculations indicate that pre-induced anisotropy with an easy axis perpendicular to the applied stress effectively resists the change in the magnetization direction during bending. These results are of importance for realizing better performance of flexible spin valve devices and the development of flexible spintronics. Published by AIP Publishing.

Antiferromagnetic (AFM) materials are of great interest for spintronics. Here, we report the magnetoelastic anisotropy of an AFM IrMn thin film. An exchange-biased CoFeB/IrMn bilayer was used to obtain a single domain of the AFM thin film, and the magnetic moment arrangement of the AFM layer was deduced from the magnetic hysteresis loop of the pinned FM layer. A uniaxial compressive stress is applied on the thin film through changing the temperature due to the anisotropic thermal expansion of the polyvinylidene fluoride (PVDF) substrate. Both experimental results and theoretical calculations show that the direction of IrMn magnetic moment can be changed when a compressive stress is applied and the direction of IrMn AFM moment rotates about 10° under 2.26 GPa compressive stress. These results provide important information for the practical application of flexible spintronics based on AFM spintronic devices.

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Large magnetoresistance and large magnetic field induced strain are observed in polycrystalline Ni42.8Co7.7Mn38.8Al10.7 Heusler alloy. The martensitic transformation from ferromagnetic austenite to weak‐magnetic martensite is realized in the alloy around the room temperature. A magentoresistance of −45% and magnetic field induced strain up to −500 ppm are observed under the magnetic field of 90 kOe. The evolution of the topography and magnetic domain is measured by magnetic force microscopy under different magnetic fields. Dramatic changes in magnetic domain structures are observed and discussed in the martensitic transformation process. The magnetic field induced reverse martensitic transformation should account for the large magnetoresistance and magnetic field induced strain. The results indicate the potential application of Ni42.8Co7.7Mn38.8Al10.7 alloy in magnetic multifunctional materials.

Exchange bias effect has been widely employed for various magnetic devices. The experimentally reported magnitude of exchange bias field is often smaller than that predicted theoretically, which is considered to be due to the partly pinned spins of ferromagnetic layer by antiferromagnetic layer. However, mapping the distribution of pinned spins is challenging. In this work, we directly image the reverse domain nucleation and domain wall movement process in the exchange biased CoFeB/IrMn bilayers by Lorentz transmission electron microscopy. From the in-situ experiments, we obtain the distribution mapping of the pinning strength, showing that only 1/6 of the ferromagnetic layer at the interface is strongly pinned by the antiferromagnetic layer. Our results prove the existence of an inhomogeneous pinning effect in exchange bias systems.

Objective: To predict the total number of patents of "specialized and Specialized, Fined, Peculiar and new" enterprises in Zhejiang province in the next five years, and to provide a reference for the Zhejiang Provincial government to implement scientific and modern management of "specialized and Specialized, Fined, Peculiar and new" enterprises. Method: from the ministry of three batches of "new" enterprise list using Pyton for enterprise location, understand the "new" distribution, and further analyze the "new" enterprises in Zhejiang province, mining 64 listed companies nearly ten years patent applications, using MATLAB software, using GM (1,1) model, predict the next five years "new" enterprises in the total number of listed enterprises. Conclusion: The prediction results show that in the next five years, the patent number of "Specialized, Fined, Peculiar and new" enterprises in Zhejiang Province will show an exponential growth, reflecting the strong scientific and technological innovation ability of "Specialized, Fined, Peculiar and new" enterprises.