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This study employs an optimized model to investigate the lattice deformation and band structure evolutions induced by the tensile strain along the zigzag direction of bulk black phosphorus (bulk BP) and the physical mechanisms behind it. It has been found that the tensile strain leads to the lattice expansion along the zigzag direction, while contracting along the armchair direction, and the out-of-plane lattice undergoes sequential expansion and contraction. This is also accompanied by an increasing and decreasing of the bulk energy gap and eventually reaching zero. Furthermore, one hopping factor has been proposed to connecting the interlayer spacing and the interlayer interaction, which successfully explains the strain-induced evolutions of the bulk energy gap. This work provides a theoretical reference for the strain-induced band engineering of bulk BP. [ABSTRACT FROM AUTHOR]

The rapid development of 2D magnetic materials has opened new possibilities in the field of spintronics. CrTe2, a 2D material with perpendicular magnetic anisotropy (PMA) and ferromagnetic transient temperature near room temperature, holds promise for various applications. However, the underlying mechanism responsible for its global magnetism remains unclear. This work focuses on investigating the magneto‐transport properties of ultra‐thin CrTe2 Field Effect Transistor (FET) under the influence of top gate biases. The application of gate voltage ranging from 25 to −15 V tunes its coercivity (HC) and Curie temperature (TC) (from 152 to 191 K). Notably, a linear correlation is observed between the TC and the hole concentration (np1/3$n_{\mathrm{p}}^{1/3}$) in the CrTe2 film, indicating the involvement of the Ruderman–Kittel–Kasuya–Yosida interaction. This experimental analysis sheds light on the mechanism of the CrTe2's ferromagnetism and paves the way for future advancements and applications in this material. [ABSTRACT FROM AUTHOR]

In this paper, the reports about improving the perpendicular magnetic anisotropy at the CoFeB/MgO interface in recent years were reviewed. The influence factors of the perpendicular magnetic anisotropy at the CoFeB/MgO interface were summarized from the aspects of multilayer structure (thickness of each layer, stack sequence, periodic numbers, interfacial roughness, and the degree of crystallization in the buffer, layer, ferromagnetic layer, or oxide layer), multilayer composition (composition of the ferromagnetic layer, and material types of the buffer layer and capping layer), and material process (annealing process, applied electric field and applied strain). Understanding the influence factors of the perpendicular magnetic anisotropy at the CoFeB/MgO interface is helpful to better understand the source of perpendicular magnetic anisotropy in the nonmagnetic metal/CoFeB/MgO multilayers in the deep physical mechanism and optimize the perpendicular magnetic anisotropy by using proper structure and technology. [ABSTRACT FROM AUTHOR]

The insertion of a metal (metal oxide) layer in a ferromagnetic layer is highly effective for tailoring the interfacial microstructures of magnetic multilayers and consequently their physical, chemical, and magnetic properties. In this study, the authors add Hf (HfO2) spacer layers to magnetic tunnel junctions (MTJs) with two MgO layers to ensure the perpendicular magnetic anisotropy (PMA) of the films after annealing at 375 °C. High‐resolution transmission electron microscopy shows that the MgO and Ta layers are partially crystallized, while the CoFeB layers are predominantly amorphous. The different Ta, MgO, and CoFeB layers can be easily distinguished by energy‐dispersive X‐ray spectroscopy. X‐ray photoelectron spectroscopy indicates that some HfO2 is formed when the film is deposited, and more HfO2 is formed during annealing. More Fe and Co oxides are also formed as oxygen reduced from BOx and MgO combines with Fe and Co in the CoFeB layer, which strengthens the PMA. The results indicate that the insertion of a metal (metal oxide) layer is an effective way to improve the magnetic properties of MTJs. [ABSTRACT FROM AUTHOR]