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The realization of long‐range magnetic ordering in 2D systems can potentially revolutionize next‐generation information technology. Here, the successful fabrication of crystalline Cr3Te4 monolayers with room temperature (RT) ferromagnetism is reported. Using molecular beam epitaxy, the growth of 2D Cr3Te4 films with monolayer thickness is demonstrated at low substrate temperatures (≈100 °C), compatible with Si complementary metal oxide semiconductor technology. X‐ray magnetic circular dichroism measurements reveal a Curie temperature (Tc) of v344 K for the Cr3Te4 monolayer with an out‐of‐plane magnetic easy axis, which decreases to v240 K for the thicker film (≈7 nm) with an in‐plane easy axis. The enhancement of ferromagnetic coupling and the magnetic anisotropy transition is ascribed to interfacial effects, in particular the orbital overlap at the monolayer Cr3Te4/graphite interface, supported by density‐functional theory calculations. This work sheds light on the low‐temperature scalable growth of 2D nonlayered materials with RT ferromagnetism for new magnetic and spintronic devices.

A large magnetic modulation, accompanied by stable bipolar resistive switching (RS) behavior, was observed in a Mn:ZnO film by applying a reversible electric field. A significant enhancement of the ferromagnetism of the film, to about five times larger than that in the initial (as-grown) state (IS), was obtained by switching the film into the low resistance state. X-ray photoelectron spectroscopy demonstrated the existence of abundant oxygen vacancies in the IS of the film. We suggest that this electric field-induced magnetic switching effect originates with the migration and redistribution of oxygen vacancies during RS. Our work indicates that electric switching is an effective and simple method to increase the ferromagnetism of diluted magnetic oxide films. This provides a promising direction for research in spintronic devices.

The effects of lanthanum deficiency on the structural and magnetic properties of manganites with normal composition La0.7−xSr0.3MnO3 prepared by the sol-gel method with the highest heat treatment temperature at 800 °C have been investigated. X-ray diffraction (XRD) spectra indicate that the materials possess a single phase with the R3¯c perovskite structure for x≤0.05, and that they possess two phases with the R3¯c perovskite being the dominant phase and Mn3O4 being the second phase for x≥0.10. Using XRD analysis, these materials can be expressed as La0.7−xSr0.3Mn1−yO3−1.5(x+y)/(Mn3O4)y/3. On the basis of the thermal equilibrium theory of crystal defects, the ion ratios at the A, B, and O sites in the ABO3 perovskite phase were calculated. Those ion ratios were used in Rietveld fitting of the XRD spectra. It was found that the dependence of the Curie temperature TC on the content ratio RM4 of Mn4+ ions at B site is similar to that of the typical perovskite La1−xSrxMnO3.

A method based on the thermal equilibrium theory of crystal defects for estimating the Mn4+ ion content ratio (RM4) at B sites in ABO3 self-doped manganite La1−xMnO3−δ is presented. For this kind of manganite, the relationship between the Curie temperature (TC) and RM4 can be explained by the double exchange mechanism of Zener, which is similar to that in the perovskite manganite La1−xCaxMnO3.

The inter-grain exchange-coupling interactions, effective anisotropy, and coercivity in nanocomposite Nd2Fe14B/α−Fe magnets were investigated. The effective anisotropy of nanocomposite magnets has been calculated starting from the statistics of boundaries between magnetically hard-hard, hard-soft, and soft-soft grains. The result shows that the effective anisotropy decreases with reduction in grain size and/or increase in soft phase components. When grain sizes reduce to 4–5 nm, Keff decreases to 1/3−1/4 of the ordinary value of K. The coercivity in nanocomposite magnets demonstrates a similar behavior. The decrement of coercivity is mainly due to the reduction of effective anisotropy. Considering the opposite varying trend the remanence demonstrates with respect to the effective anisotropy and the coercivity, we conclude that the mean grain size should be in the range of 10–15 nm and the volume fraction of soft phase should be less than 50% in order to achieve high energy product magnets.

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