Results of superconducting transition temperature measurements are presented for the bulk metallic glass Zr46.75Ti8.25Cu7.5Ni10Be27.5 before and after annealing. The superconducting critical temperature Tc is 1.84 K for the as-prepared metallic glassy sample and 3.76 K for the annealed sample at zero magnetic field, respectively. The temperature gradient (−dHc2/dT)Tc of the upper critical field Hc2 near the critical temperature Tc of the bulk metallic glass Zr46.75Ti8.25Cu7.5Ni10Be27.5 is about 2.5 T K−1. Annealing of the metallic glass leads to a decrease of (−dHc2/dT)Tc to 1.2 T K−1. The origin of the reduction of the critical temperature Tc in the amorphous Zr46.75Ti8.25Cu7.5Ni10Be27.5 is ascribed to a smearing of the density of states by the disordered atomic structure.
Hafnium oxide (HfO2), particularly at low-dimensional scales, exhibits extensive promising applications in ultrahigh density devices like low-power logic and non-volatile memory devices due to its compatibility with current semiconductor technology1-5. However, achieving ferroelectricity (FE) at ultimate scale especially in undoped HfO2 remains challenging as the non-centrosymmetric FE phase, so-called O-III (space group: Pca21) is metastable and FE has a strong tendency of depolarization with the decrease in thickness6. Up to now, this phase has usually stabilized via doping with other elements7-9. But the minimum film thickness is still limited to 1 nm, about 2-unit-cell, to keep FE8. Thinner and undoped films, conducive to further miniature device size and avoid contamination during deposition process, have been a challenge to fabricate on Si substrates. Herein, we report the robust FE observed in undoped HfO2 ultrathin films directly grown on Si substrate via atomic layer deposition (ALD) and post-heat treat in vacuum. The so-fabricated ferroelectric O-III phase contains about 4.48 at% oxygen vacancy, is robust even monoclinic phase (space group: P21/c) coexists. The spontaneous and switchable polarization is remarkably stable, still surviving even in films down to 0.5 nm (one-unit-cell). Our results show the robust FE O-III phase can be obtained in films down to one-unit-cell in thickness on Si, providing a practical way to fabricating this important material in thickness limit.
Boson peaks are observed in glassy materials due to atom, spin, and strain disordered states that provide additional vibration modes at low temperatures. However, Boson peaks have not been observed in pure dipole disordered systems without structural disorder. Here, we report the observation of a Boson-peak-like hump in specific heat near 7 K in organic-inorganic hybrid crystal $M{A}_{4}{\mathrm{InCl}}_{7}(MA={\mathrm{CH}}_{3}{\mathrm{NH}}_{3})$. The energy barrier for unbonded Cl anions migration is extremely low, allowing that the migration persists down to low temperatures. The migration and the subsequent relaxation process induce a random change in its dipole, leading to the dipole disorder states. Our results show that $M{A}_{4}{\mathrm{InCl}}_{7}$ can be regarded as a dipole glass that can give rise to the Boson peak as well.
This work successfully synthesized S 0.66(2) WS 2 bulk single crystals, confirming the successful intercalation of sulfur in the M-WS 2 interlayer space.
The van der Waals materials Ge 0.33 NbS 2 and Ge 0.26 NbSe 2 have been synthesized via the chemical vapor transport method and the former shows ultrahigh conductivity at room temperature due to its non-trivial topological band structure.
We have successfully achieved the nonpolar-polar transition to a polar junction in apatite materials by using size-differentiated atomic substitution to induce spontaneous polarization, and prepared a material with excellent pyroelectric properties.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
A coherent mode (CM) in the edge pedestal region has been observed on different fluctuation quantities, including density fluctuation, electron temperature fluctuation and magnetic fluctuation in H mode plasma on the Experimental Advanced Superconducting Tokamak (EAST) tokamak. Measurements at different poloidal positions show that the local poloidal wavenumber is smallest at the outboard midplane and will increase with poloidal angle. This poloidal asymmetry is consistent with the flute-like assumption (i.e. k// ~ 0) from which the toroidal mode number of the mode has been estimated as between 12 and 17. It was further found that the density fluctuation amplitude of the CM also demonstrated poloidal asymmetry. The appearance of a CM can clearly decrease or even stop the increase in the edge density, while the disappearance of a CM will lead to an increase in the pedestal density and density gradient. Statistical analysis showed there was a trend that as the CM mode amplitude increased, the rate of increase of the edge density decreased and the particle flux (Γdiv) onto the divertor plate increased. The CM sometimes showed burst behavior, and these bursts led bursts on Γdiv with a time of about 230 μs, which is close to the time for particle flow from the outer midplane to the divertor targets along the scrape-off layer magnetic field line. This evidence showed that the CM had an effect on the outward transport of particles.
Abstract C 12 H 32 O 10 Cu 2 Cl 4 , monoclinic, P 2 1 / n (no. 14), a = 9.0202(4) Å, b = 9.5791(4) Å, c = 13.6994(6) Å, β = 92.555(1) ° , V = 1182.53(9) Å 3 , Z = 2, R gt ( F ) = 0.0308, wR ref ( F 2 ) = 0.0800, T = 293(2) K.
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