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• Methodology for fracture energy estimation of pores located at bonded interface is proposed. • Extended J-integral approach with proper integral path is utilized and demonstrated. • Several porosity levels and distribution of porous materials are modeled by Monte Carlo approach. • Semiconductor low-k stacked films are given as an example by using the present estimation. • Important factors of interfacial fracture are found by the response surface methodology. In view of the fracture failure mechanism induced by low interfacial strength in porous low-dielectric materials, this study establishes an approach based on fracture mechanics theory and finite element simulation to analyze different pore distribution scenarios and interfacial cracks. The study investigates the estimation method of energy release rate for the fracture tip on concerned interfaces with pores and cracks in porous stacked thin films. By incorporating the proposed finite element simulation into J-integral calculations for fracture energy release rate and comparing with previous research, the approach is reliably verified. Subsequently, using the developed simulation approach, cracks and pores in porous materials are analyzed to understand the variations of energy release rates under different structural parameters. Finally, a Monte Carlo method is considered to model porous materials and analyze the fracture energy between dissimilar material interfaces under varying porosity levels. The simulation methodology developed in this study can be applied to estimate the critical value of interfacial fracture energy for corresponding porous materials and heterogeneous material interfaces under external loads. It can serve as a criterion for structural failure assessment. [ABSTRACT FROM AUTHOR]

The design of multicomponent materials has captured considerable attention due to its extraordinary ability to tailor functional properties. However, how a single element affects the behavior of the overall material has yet to be explored in depth. In this study, the heteroepitaxy of high entropy (Fe, Co, Ni, Cr, Mn)3O4 films with varying strain states are investigated in magnetic performance. It is discovered that the high entropy oxide thin film with compressive strain exhibits an effect of crystalline magnetic anisotropy. Diverse analyses provide a detailed understanding of high entropy magnetic oxide systems, including X‐ray diffraction, reciprocal space mapping, macroscopic magnetic characterization, X‐ray absorption spectroscopy (XAS), etc. Notably, the element‐specific XAS technique proves effective in uncovering the origin of the crystalline magnetic anisotropy. Due to the substrate‐induced epitaxial strain, the eg orbitals of Mn3+ form different energy levels, leading to different preferred electron occupancy. The exploration of magnetic properties in epitaxial high entropy oxide film is then raveled. By navigating the complexities introduced by the random atom distribution and intricate magnetic interactions, this study pioneers novel methodologies for probing the core physics of high entropy oxides. [ABSTRACT FROM AUTHOR]

The origin of insulating ferromagnetism in epitaxial LaCoO3 films under tensile strain remains elusive despite extensive research efforts are devoted. Surprisingly, the spin state of its Co ions, the main parameter of its ferromagnetism, is still to be determined. Here, the spin state in epitaxial LaCoO3 thin films is systematically investigated to clarify the mechanism of strain‐induced ferromagnetism using element‐specific X‐ray absorption spectroscopy and dichroism. Combining with the configuration interaction cluster calculations, it is unambiguously demonstrated that Co3+ in LaCoO3 films under compressive strain (on LaAlO3 substrate) is practically a low‐spin state, whereas Co3+ in LaCoO3 films under tensile strain (on SrTiO3 substrate) have mixed high‐spin and low‐spin states with a ratio close to 1:3. From the identification of this spin state ratio, it is inferred that the dark strips observed by high‐resolution scanning transmission electron microscopy indicate the position of Co3+ high‐spin state, i.e., an observation of a spin state disproportionation in tensile‐strained LaCoO3 films. This consequently explains the nature of ferromagnetism in LaCoO3 films. The study highlights the importance of spin state degrees of freedom, along with thin‐film strain engineering, in creating new physical properties that do not exist in bulk materials. [ABSTRACT FROM AUTHOR]

Development of metallic thin films with comprehensive properties fulfilling the needs of modern Micro/Nano Electro Mechanical Systems (M/NEMS) devices remains challenging. Here, a fully amorphous Ta 90 Co 10 is screened out by combinatorial sputtering and atomic manufacturing technique, and the Ta 90 Co 10 thin film metallic glass exhibits simultaneously a super-high crystallization temperature of 1325 K, a high hardness of 16.3 GPa, a high strength of 5000 MPa, and a large plastic strain exceeding 50%, outperforming all existing thin film materials. The excellent properties can be attributed to the atomic-scale structural heterogeneity induced by formation of different configurations in amorphous structure. The present work provides an approach to develop new M/NEMS-based thin film materials with outstanding comprehensive properties. [Display omitted] [ABSTRACT FROM AUTHOR]

This research explores the behavior of Co40Fe40W10B10 when it is sputtered onto Si(100) substrates with a thickness (tf) ranging from 10 nm to 100 nm, and then altered by an annealing process at temperatures of 200 °C, 250 °C, 300 °C, and 350 °C, respectively. The crystal structure and grain size of Co40Fe40W10B10 films with different thicknesses and annealing temperatures are observed and estimated by an X-ray diffractometer pattern (XRD) and full-width at half maximum (FWHM). The XRD of annealing Co40Fe40W10B10 films at 200 °C exhibited an amorphous status due to insufficient heating drive force. Moreover, the thicknesses and annealing temperatures of body-centered cubic (BCC) CoFe (110) peaks were detected when annealing at 250 °C with thicknesses ranging from 80 nm to 100 nm, annealing at 300 °C with thicknesses ranging from 50 nm to 100 nm, and annealing at 350 °C with thicknesses ranging from 10 nm to 100 nm. The FWHM of CoFe (110) decreased and the grain size increased when the thickness and annealing temperature increased. The CoFe (110) peak revealed magnetocrystalline anisotropy, which was related to strong low-frequency alternative-current magnetic susceptibility (χac) and induced an increasing trend in saturation magnetization (Ms) as the thickness and annealing temperature increased. The contact angles of all Co40Fe40W10B10 films were less than 90°, indicating the hydrophilic nature of Co40Fe40W10B10 films. Furthermore, the surface energy of Co40Fe40W10B10 presented an increased trend as the thickness and annealing temperature increased. According to the results, the optimal conditions are a thickness of 100 nm and an annealing temperature of 350 °C, owing to high χac, large Ms, and strong adhesion; this indicates that annealing Co40Fe40W10B10 at 350 °C and with a thickness of 100 nm exhibits good thermal stability and can become a free or pinned layer in a magnetic tunneling junction (MTJ) application. [ABSTRACT FROM AUTHOR]