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A ferroelectric thin film epitaxially deposited on a substrate is usually subjected to the mixed mechanical boundary conditions that can neither be treated as purely fixed-strain boundaries nor purely fixed-stress ones, thus causing the inconsistency or inaccuracy for choice of the Helmholtz or Gibbs thermodynamic potential. It would be of interest to clarify this inconsistency and set up some rules for such a choice. In this work, we discuss various roadmaps to construct two types of modified thermodynamic potentials under the epitaxial thin film boundary conditions. The equivalence of these thermodynamic potentials is then established. Subsequently, a set of misfit strain–strain phase diagrams by choosing K0.5Na0.5NbO3 thin films as an example of realistic calculations are constructed to check this equivalence. Finally, some scenarios on choosing various thermodynamic potentials for ferroelectric thin films are discussed. [ABSTRACT FROM AUTHOR]

With the discovery of two-dimensional (2D) ferroelectricity and ferromagnetism in van der Waals (vdW) materials, there has been significant interest in 2D multiferroics. Herein, we report the occurrence of weak ferromagnetism and magnetoelectricity in vdW antiferromagnet MnPSe3 single crystals. Our results demonstrate that MnPSe3 undergoes an antiferromagnetic transition at the Néel temperature TN = 70 K with weak ferromagnetism along the [1–10] direction. Detailed magnetoelectric (ME) data show that MnPSe3 exhibits a linear ME tensor αij with nine nonzero components. Additionally, a magnetically induced electric polarization as large as 98.5 μC/m2 is observed along the [110] direction, with a ME coefficient of 13.5 ps/m at 10 K for a magnetic field of 9 T applied along the [110] direction. Importantly, we discuss our experiments based on symmetry and microscopic analysis, thereby suggesting that the spin-dependent p-d hybridization mechanism plays an important role in the emergence of magnetic-field-induced ferroelectricity. Hence, our findings provide insights for exploring the ME coupling in vdW materials. [ABSTRACT FROM AUTHOR]

Antiferromagnetic spintronics has been receiving attention recently, while spin-texture dependent magnetoresistance (MR) represents one of the main mechanisms for magnetic data storage. In particular, sufficiently large MR with high operating temperatures would be highly required for advanced spintronic applications. In this work, we experimentally investigate the MR effect of well-known antiferromagnet α-Fe2O3 (hematite) in a single crystal form, which has the Morin transition temperature as high as Tm ∼ 260 K. It is revealed that the MR effect associated with the spin-texture re-alignment, i.e., the spin-flop from the out-of-plane direction (c axis) to the in-plane direction, driven by sufficiently low magnetic fields inclined along the [012] direction, reaches up to ∼2.5% at temperature T ∼ 250 K. The first-principles calculations suggest that this MR effect originates from the reduced bandgap due to the spin-flop and the finite spin–orbital coupling. The present work sheds light on the possibility of α-Fe2O3 as a favored MR-based candidate for near-room temperature spintronics. [ABSTRACT FROM AUTHOR]

The new sesquiterpenoid (6 R )-2-chloro-6-[(1 S )-1,5-dimethylhex-4-en-1-yl]-3-methylcyclohex-2-en-1-one (1), together with ten known compounds, (6 R )-6-[(1 S )-1,5-dimethylhex-4-en-1-yl]-3-methylcyclohex-2-en-1-one (2), bauerenol acetate (3), lupenone (4), α-amyrenone (5), β-sitosterol (6), stigmasterol (7), β-amyrin (8), ursolic acid (9), betulinic acid (10), scopolin (11), have been isolated from the roots of Euphorbia chrysocoma Lévl. et Vant. Their structures have been elucidated by spectroscopic data. [ABSTRACT FROM AUTHOR]

Radix Adenophorae (Shashen), a traditional Chinese medicine commonly used as an antitussive and expectorant, is derived from roots of Adenophora stricta Miq. and Adenophora tetraphylla (Thunb.) Fisch. Twelve species and varieties of Adenophora and Glehnia, however, could act as substitutes or adulterants of Radix Adenophorae on the commercial markets in South East Asia, and roots of Adenophora hunanensis Nannf. and Glihnia littoralis F. Schmidt ex Miq. are the most common examples. The authentic identification of dried roots of A. stricta and A. tetraphylla, however, is difficult on the basis of appearance and morphology. A molecular genetic approach was developed here to identify the species of Radix Adenophorae. The 5S-rRNA spacer domains (~250 bp) were amplified by the polymerase chain reaction (PCR) from genomic DNAs isolated from A. stricta, A. tetraphylla, A. hunanensis and G. littoralis, and subsequently, the nucleotide sequences were determined. Diversity in DNA sequence and restriction enzyme mapping among various species were found in their 5S-rRNA spacer domains, which could serve as markers for authentic identification of Radix Adenophorae. [ABSTRACT FROM AUTHOR]

The moiré-pattern with slightly interlayer-twisted bilayer two-dimensional (2D) materials has recently been receiving substantial attention. One of the major characters for these intriguing structures is the appearance of low-energy ultra-flat bands and thus a package of new physics associated with strong electron correlation emerges. However, such new physics may become vague unless the twist-angle θ is sufficiently small such as θ ∼ 1°, making practical applications and control-flexibility hard to handle. In this work, we explore the possible flat-band moiré physics in recently concerned 2D bilayer α-In2Se3 which is antiferroelectric with sublayer out-of-plane (OP) polarizations, addressing the potential role of polarization-bound charges in modulation of electron–electron correlation and interlayer hybridization, based on the extensive first-principles calculations. On one hand, it is found that the low energy band becomes extremely flat in the bilayer α-In2Se3 moiré-pattern with relatively large twist-angle, e.g. θ = 13.17°, which is more easily accessible experimentally. On the other hand, the impact of the sublayer OP polarizations on the band structure is asymmetric, and the flattening effect is much more remarkable for the end-to-end polarization alignment but weaker for the head-to-head alignment. This work thus opens a broad roadmap for technological access to artificial fabrication of novel moiré-patterned 2D materials by means of low-dimensional ferroelectricity. [ABSTRACT FROM AUTHOR]

A novel gel tape casting process has been developed by introducing sodium alginate into a conventional aqueous tape casting slurry. The process makes use of a binder system consisting of 1 wt-% sodium alginate and 20 vol.-% styrene acrylic latex to prepare the tape casting slurry. Sodium alginate can react with calcium iodate to form a three-dimensional network at room temperature, and with the ceramic particles held in this three-dimensional network, the slurry can be consolidated to form green tapes. This allows the need for the special drying procedure that is usually a critical step in tape casting to be avoided. Styrene acrylic latex was used to improve the flexibility of the green tapes. Compared with tapes obtained by conventional aqueous tape casting, more homogeneous microstructure was obtained by this process. [ABSTRACT FROM AUTHOR]