Permalloy
with low ferromagnetic resonance linewidth has great
application potential in spintronic/microwave devices. In this work,
we demonstrated that the nonmagnetic (Cu) layer’s sputtering
rate has a considerable impact on Ni0.81Fe0.19’s linewidth in Cu (4 nm)/Ni0.81Fe0.19 (3 nm) bilayer heterostructures. A monotonically decreasing out-of-plane
linewidth was displayed as the sputtering rates increased from 0.27
to 1.75 Å/s due to interdiffusion. Meanwhile, a large reduction
of the in-plane linewidth from 18.54 to 7.83 mT was also obtained
from suppressing the interfacial inhomogeneity and two-magnon scattering
effects. The present work contributes to a clearer understanding of
Cu/Ni0.81Fe0.19 nanoscale films’ interfacial
inhomogeneity and opens a new road on tailoring magnetodynamic properties.
CZTS thin films are fabricated by sulfurizing co-sputtered metallic precursor CuZnSn layers under H2S atmosphere. The precursor layers are Cu-poor, Zn-rich deposited and the fabricated films are about 2 µm in thickness. A closed-tube process is preferred with regard to its producing large closely pack grains with smooth surface. XRD and Raman confirm the CZTS structure and the impurities on the surface are removed after suitable chemistry treatments. The band gap of the CZTS is determined to be 1.48 eV by extrapolation. Some more CZTS films are product with slightly changed parameters, sulfurization time, temperature and concentration of H2S, respectively. It is supposed that beside sulfurization time, the temperature could be more significant than concentration of H2S in the closed system.
Perovskite materials with compositions in the vicinity of the steep morphotropic phase boundary (MPB) exhibit various intriguing properties including giant piezoelectricity and large dielectric constant. Aside from composition, the phase configuration of the perovskites is also strongly related to the ambient temperature. Here, we report a giant piezoelectricity of 10 980 pm/V at 93°C in the 0.7Pb(Mg 1/3 Nb 2/3) O 3-0.3PbTiO 3 (PMN-PT) single crystals which is more than five times larger than that at room temperature. The enhanced piezoelectricity can be attributed to the instability of the thermally induced tetragonal phase which can be converted to the orthorhombic phase by the external electric field in the <011> oriented single crystal. The transverse piezoelectricity has been investigated by measuring the electric-fielddependent ferromagnetic resonance (FMR) field in the CoFeB/PMN-PT magnetoelectric (ME) heterostructures. The ME coupling coefficient has been increased from 49.3 to 476 Oe cm/kV as temperature increased from 25 to 90°C. The findings reveal that both longitudinal and transverse piezoelectricity in the PMN-PT single crystals can be greatly enhanced by proper setting of ambient temperature, indicating an effective route for the design of strain-mediated tunable devices with ultralow driving voltage. K E Y W O R D S ferromagnetism/ferromagnetic materials, magnetoelectrics, phase transformations, piezoelectric materials/properties How to cite this article: Du Q, Wang W, Wang Z, et al. Thermally activated giant piezoelectricity and enhanced interface elastic strain-mediated magnetoelectric coupling.
Large working range is of vital importance for magnetic sensors when exposed to complicated magnetic field profile, especially in automation and power industry where large field variation is frequently encountered. The design for traditional magnetic sensors, e.g., magnetoresistive and fluxgate magnetometers, utilizes ferromagnetic materials with ultrahigh permeability to maximize the field sensitivity, resulting in strictly confined dynamic range due to limited saturation field. Here, an integratable ferromagnetic resonance (FMR) prototype magnetic sensor with high sensitivity and theoretically unlimited working range is reported. An ultrawide working range (>450 mT) which is more than two orders larger than that of commercial sensors with similar field resolution is experimentally verified. Moreover, the FMR magnetometer is a vector sensor in contrast to the traditional scalar sensors based on magnetic resonance. With a navigating magnetic field of 50 μT (ca. the Earth's magnetic field), the resolution for azimuth angle is 0.006°. Compared with traditional nuclear magnetic resonance and electron paramagnetic resonance sensors with large size and high power consumption, the compact FMR sensor with large dynamic range and high sensitivity has much broader application prospects, especially in magnetically harsh environments.
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