The absence of two-dimensional (2D) van der Waals (vdW) ferromagnetic crystals with both above-room-temperature strong intrinsic ferromagnetism and large perpendicular magnetic anisotropy (PMA) severely hinders practical applications of 2D vdW crystals in next-generation low-power magnetoelectronic and spintronic devices. Here, we report a vdW intrinsic ferromagnetic crystal Fe3GaTe2 that exhibits record-high above-room-temperature Curie temperature (Tc, ~350-380 K) for known 2D vdW intrinsic ferromagnets, high saturation magnetic moment (40.11 emu/g), large PMA energy density (~4.79 × 105 J/m3), and large anomalous Hall angle (3%) at room temperature. Such large room-temperature PMA is better than conventional widely-used ferromagnetic films like CoFeB, and one order of magnitude larger than known 2D vdW intrinsic ferromagnets. Room-temperature thickness and angle-dependent anomalous Hall devices and direct magnetic domains imaging based on Fe3GaTe2 nanosheet have been realized. This work provides an avenue for room-temperature 2D ferromagnetism, electrical control of 2D ferromagnetism and promote the practical applications of 2D-vdW-integrated spintronic devices.

Commercial lead-based piezoelectric materials raised worldwide environmental concerns in the past decade. Bi 0.5 Na 0.5 TiO 3 -based solid solution is among the most promising lead-free piezoelectric candidates; however, depolarization of these solid solutions is a longstanding obstacle for their practical applications. Here we use a strategy to defer the thermal depolarization, even render depolarization-free Bi 0.5 Na 0.5 TiO 3 -based 0-3-type composites. This is achieved by introducing semiconducting ZnO particles into the relaxor ferroelectric 0.94Bi 0.5 Na 0.5 TiO 3 -0.06BaTiO 3 matrix. The depolarization temperature increases with increasing ZnO concentration until depolarization disappears at 30 mol% ZnO. The semiconducting nature of ZnO provides charges to partially compensate the ferroelectric depolarization field. These results not only pave the way for applications of Bi 0.5 Na 0.5 TiO 3 -based piezoceramics, but also have great impact on the understanding of the mechanism of depolarization so as to provide a new design to optimize the performance of lead-free piezoelectrics.

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The discovery of type‐II Weyl semimetal states in layered transition metal dichalcogenides Td‐WTe2 indicates great potential for novel electronic, spintronic, and quantum devices. Theoretically, the interaction between the topological states and the magnetic ordered states of Td‐WTe2 enables the modulation of Weyl semimetal states by an external magnetic field. However, currently, ferromagnetism in layered Td‐WTe2 is still elusive and rarely observed. In this research, ferromagnetic order into WTe2 using magnetic chromium (Cr) doping with a two‐step Te flux strategy is introduced. The Curie temperature (Tc) and the ferromagnetic moment are well tuned with a Cr doping concentration. The Tc of the Cr‐doped layered Td‐WTe2 could be regulated from 182 to 283 K, which is close to room temperature. The saturation magnetic moment could be changed from 2.26 to 4.20 emu g–1, which is stronger than most values reported for these materials. Most intriguingly, the Cr‐doped layered Td‐WTe2 single crystals still exhibit semimetallic behavior and they possess very large magnetoresistance with obvious Shubnikov de Haas (SdH) quantum oscillations and an anomalous Hall effect. The findings offer feasible ways to induce and tune ferromagnetic orders in layered Td‐WTe2 and thus to control its topological phase with external magnetic fields.

A comprehensive approach for the separation and identification of components in a traditional Chinese medicine Lobelia chinensis Lour. was developed using 2D-HPLC coupled with an online photodiode array (PDA) detector and a mass spectrometer. The extract of L. chinensis Lour. was separated on a CN column in the first-dimensional HPLC, and then each of the collected fractions was further separated on an ODS column followed by an online PDA detector. After separation in the two different chromatographic modes, the eluents were delivered to a quadrupole mass spectrometer equipped with a multimode ion source of an ESI and an atmospheric pressure chemical ionization (ESI/APCI). At least 536 components in L. chinensis Lour. extract were detected and 6 of them were identified as apigenin 7-O-rutinoside, luteolin, lobetyolinin, lobetyolin, diosmin, and linarin, respectively, according to their UV spectrum and mass spectrum. The results demonstrated the powerful resolution, high peak capacity, as well as the identification capability of the 2D-HPLC combined with PDA and ESI/APCI-MS for the analyses of complex samples.