Phys.org March 6, 2024 Zero-index metamaterials (ZIMs) can support uniform electromagnetic field distributions at any frequency, but their applications are hampered by the ZIM’s homogenization level—only 3-unit cells per free-space wavelength, which is fundamentally limited by the low-permittivity inclusions and background matrix. An international team of researchers (USA – Stanford University, China) demonstrated a highly homogeneous microwave ZIM with an over threefold increase in the homogenization level by filling high-permittivity SrTiO3 ceramic pillars in BaTiO3 background matrix. They achieved an antenna, and a concave lens with a focal length of as short as 1λ0… read more. Open Access TECHNICAL ARTICLE
Tag Archives: Materials science
New adhesive tape picks up and sticks down 2D materials as easily as child’s play
Science Daily February 9, 2024 The use of graphene and other 2D materials to create electronic and optoelectronic devices has been limited by the lack of effective large-area transfer processes. An international team of researchers (South Korea, Japan) has developed a method that uses functional tapes with adhesive forces controlled by ultraviolet light. The adhesion of the tape was optimized for the transfer of monolayer graphene, providing a yield of over 99%. Once detached from the growth substrate, the graphene/tape stack enables easy transfer of graphene to the desired target substrate. The method could be used to transfer other 2D […]
Scientists shed light on the inner workings of a new class of unconventional superconductors
Phys.org February 7, 2024 The discovery of superconductivity in infinite-layer nickelates established another category of unconventional superconductors that shares structural and electronic similarities with cuprates. However, key issues of the superconducting pairing symmetry, gap amplitude and superconducting fluctuations are yet to be addressed. A team of researchers in the US (Ames National Laboratory, SLAC National Laboratory, Stanford University) utilized static and ultrafast terahertz spectroscopy and demonstrated that the equilibrium terahertz conductivity and non-equilibrium terahertz responses of an optimally Sr-doped nickelate film are in line with the electrodynamics of d-wave superconductivity in the dirty limit. The gap-to-Tc ratio of 3.4 indicated […]
Physicists develop highly robust time crystal
Phys.org February 1, 2024 Crystals spontaneously break the continuous translation symmetry of free space. An international team of researchers (Germany, Russia) demonstrated a robust continuous time crystal in an electron–nuclear spin system of a semiconductor tailored by tuning the material composition. Continuous, time-independent external driving of the sample produced periodic auto-oscillations with a coherence time exceeding hours. Varying the experimental parameters revealed wide ranges in which the time crystal remained stable. At the edges of these ranges, they found chaotic behaviour with a lifted periodicity corresponding to the melting of the crystal. According to the researchers time crystal state enabled […]
Scientists make breakthrough in quantum materials research
Science Daily January 31, 2024 Although fine-tuning of topologically protected states in quantum materials holds great promise for novel electronic devices, there are limited methods that allow for the controlled and efficient modulation of the crystal lattice while simultaneously monitoring the changes in the electronic structure within a single sample. A team of researchers in the US (UC Irvine, Los Alamos National Laboratory, University of Tennessee) applied significant and controllable strain to high-quality HfTe5 samples and performed electrical transport measurements to reveal the topological phase transition from a weak topological insulator phase to a strong topological insulator phase. After applying […]
Short X-ray pulses reveal source of light-induced ferroelectricity in SrTiO?
Phys.org February 1, 2024 An international team of researchers (Germany, USA, Switzerland, UK) studied the time evolution of lattice fluctuations in the quantum paraelectric SrTiO3, in which mid-infrared drives have been shown to induce a metastable ferroelectric state. Crucial in these physics is the competition between polar instabilities and antiferrodistortive rotations, which in equilibrium frustrate the formation of long-range ferroelectricity. They made use of high-intensity mid-infrared optical pulses to resonantly drive the Ti–O-stretching mode at 17?THz, and measured the resulting change in lattice fluctuations using time-resolved X-ray diffuse scattering at a free-electron laser. They observed a long-lived quench in R-point […]
Tracking unconventional superconductivity
Science Daily January 31, 2024 In order to better understand the field-resistant superconducting phase, an international team of researchers (Germany, Japan, France) conducted magnetic-torque and magnetotransport measurements in pulsed magnetic fields. They determined the record-breaking upper critical field of ?0Hc2???73?T and its evolution with angle. The normal-state Hall effect experiences a drastic suppression indicative of a reduced band polarization above Hm in the angular range around 30° caused by a partial compensation between the applied field and an exchange field. According to the researchers this promotes the Jaccarino-Peter effect as a likely mechanism for the reentrant superconductivity above Hm… read […]
A type of plastic that can be shape-shifted using tempering
Phys.org February 2, 2024 A team of researchers in the US (University of Chicago, S DEVCOM Army Research Laboratory, NIST, NASA Glenn Research Center, Northwestern University) applied concept of pluripotency to adjust the microstructure of a range of materials, including many metals. They achieved through the inclusion of thia-Michael bonds that are relatively weak and capable of reshuffling at lower temperatures compared with the covalent bonds in the polymer. At higher tempering temperatures, the cross-link density of the thia-Michael network decreased, resulting in a lower stiffness of the material, whereas tempering at lower temperatures created a stiffer material. The material […]
Field-induced superconductivity in quantum materials
Phys.org December 12, 2023 Field-induced superconductivity is a rare phenomenon where an applied magnetic field enhances or induces superconductivity. A team of researchers in the US (MIT, Argonne National Laboratory, University of Washington, George Mason University) combined tunable uniaxial stress and applied magnetic field on the ferromagnetic superconductor Eu(Fe0.88Co0.12)2As2 to shift the field-induced zero-resistance temperature between 4 K and a record-high value of 10 K. They used x-ray diffraction and spectroscopy measurements under stress and field to reveal that strain tuning of the nematic order and field tuning of the ferromagnetism act as independent control parameters of the superconductivity. Combining […]
Newly developed material gulps down hydrogen, spits it out, protects fusion reactor walls
Phys.org December 14, 2023 An international team of researchers (USA, South Korea, France, Germany) investigated tantalum (Ta) coating deposited by cold spray technology on 316L stainless steel substrate as a potential plasma-facing material surface. High fluence low energy deuterium plasma irradiation experiments and subsequent thermal annealing cycles associated with thermal desorption spectrometry (TDS) demonstrated superior structural stability of the Ta coating. TDS experiments revealed the outgassing of deuterium (as measure of its retention) for cold spray Ta coatings to be three times higher than bulk Ta and two orders of magnitude greater than bulk polycrystalline W. X-ray photoelectron spectroscopy revealed […]