Science Daily February 21, 2024 The fractional quantum anomalous Hall effect (FQAHE), the analogue of the fractional quantum Hall effect at zero magnetic field, is predicted to exist in topological flat bands under spontaneous time-reversal-symmetry breaking. The demonstration of FQAHE could lead to non-Abelian anyons that form the basis of topological quantum computation. So far, FQAHE has been observed only in twisted MoTe2 at a moiré filling factor v > 1/2. Graphene-based moiré superlattices are believed to host FQAHE with the potential advantage of superior material quality and higher electron mobility. At zero magnetic field, an international team of researchers (USA – […]
Category Archives: Materials science
Physicists detect elusive ‘Bragg glass’ phase with machine learning tool
Phys.org February 9, 2024 Detecting the Bragg glass phase has been challenging despite its sharp theoretical definition in terms of diverging correlation lengths. A team of researchers in the US (Cornell University, Stanford University, National Accelerator Laboratory, Argonne National Laboratory provided bulk probe evidence supporting a Bragg glass phase in the systematically disordered charge-density-wave material of PdxErTe3. They established a diverging correlation length in samples with moderate intercalation over a wide temperature range. According to the researchers their work advances our understanding of the complex interplay between disorder and fluctuation and the use of their analysis technique to target fluctuations […]
Magnesium protects tantalum, a promising material for making qubits
Phys.org February 5, 2024 To scale up superconducting quantum circuits based on transmon qubits, substantial enhancements in qubit coherence time is necessary. Tantalum (Ta) has emerged as a promising candidate in this regard. However, amorphous surface Ta oxide layer may introduce dielectric loss limiting the coherence time. A team of researchers in the US (Brookhaven National Laboratory, Pacific Northwest National Laboratory, Princeton University) developed a new approach for suppressing the formation of tantalum oxide using an ultrathin magnesium (Mg) capping layer. They demonstrated that oxide was confined to an extremely thin region directly beneath the Mg/Ta interface, and that the […]
Strange New Kind of Magnetism Found Lurking In Material Just Six Atoms Thick
Science Alert February 4, 2024 The existence of alternate mechanisms for magnetism that could naturally facilitate electrical control has been discussed theoretically but an experimental demonstration has not been done. An international team of researchers (Switzerland, Spain, US -University of Tennessee, Japan) investigated MoSe2/WS2 van der Waals heterostructures in the vicinity of Mott insulator states of electrons forming a frustrated triangular lattice and observed direct evidence of magnetic correlations originating from a kinetic mechanism. By directly measuring electronic magnetization they found that when the Mott state was electron-doped, the system exhibited ferromagnetic correlations in agreement with the Nagaoka mechanism… read […]
Researchers add a ‘twist’ to classical material design
Phys.org January 24, 2024 Epitaxial growth of a crystalline film normally proceeds from one substrate. Researchers at Stanford University expanded the concept of epitaxy to a regime of “twisted epitaxy” with the epilayer crystal orientation between two substrates influenced by their relative orientation. They annealed nanometer-thick gold nanoparticles between two substrates of exfoliated hexagonal molybdenum disulfide with varying orientation of their basal planes with a mutual twist angle ranging from 0° to 60°. For larger twist angles, Au had only a small misorientation with the bottom MoS2. Further revealed a periodic strain variation (<|±0.5%|) in the Au nanodisks associated with […]
Researchers discover new ultra strong material for microchip sensors
Phys.org November 2, 2023 Although there have been remarkable strides in achieving low-dissipation mechanical sensors by utilizing high tensile stress, the performance of even the best strategy is limited by the tensile fracture strength of the resonator materials. An international team of researchers (the Netherlands, USA – Brown University) found that a wafer-scale amorphous thin film of silicon carbide (SiC) material exhibited an ultimate tensile strength of over 10 GPa, reaching the regime reserved for strong crystalline materials and approaching levels experimentally shown in graphene nanoribbons. They fabricated amorphous SiC strings with high aspect ratios with mechanical modes exceeding quality […]
3D-printed aluminium alloy with unprecedented fatigue resistance
Nanowerk October 24, 2023 Researchers in France have shown a fatigue resistance phenomenon in nano-TiB2-decorated AlSi10Mg enabled by additive manufacturing. This fatigue resistance mechanism benefited from the three-dimensional dual-phase cellular nanostructure, which acted as a strong volumetric nanocage to prevent localized damage accumulation fatigue crack initiation. The intrinsic fatigue strength limit of nano-TiB2-decorated AlSi10Mg was shown to be close to its tensile strength. They showed that printed bulk nano-TiB2-decorated AlSi10Mg achieved fatigue resistance more than double those of other additive manufacturing Al alloys and surpassed those of high-strength wrought Al alloys. According to the researchers their method can be extended […]
Researchers create the most water-repellent surface ever
Nanowerk October 23, 2023 Surface heterogeneity is generally acknowledged as the major cause of increased contact angle hysteresis and contact line friction of droplets. An international team of researchers (Finland, Japan) have shown that tuning the coverage of self-assembled monolayers (SAMs), water contact angles changed gradually from about 10° to 110° yet contact angle hysteresis and contact line friction were low for the low-coverage hydrophilic SAMs as well as high-coverage hydrophobic SAMs. Their slipperiness was not expected based on the substantial chemical heterogeneity of the SAMs featuring uncoated areas of the substrate well beyond the size of a water molecule […]
Working towards programmable matter: Unexpected behavior discovered in active particles
Phys.org October 23, 2023 In theoretical models for active particles, it is often assumed that the particles’ swimming speed is always the same. However, this is not so for particles produced in many experiments. An international team of researchers (UK, Germany) used a combination of computer simulations and theoretical derivations, to study the behavior of systems consisting of many active particles whose speed depended on orientation. In the process they discovered a series of new effects. They found that systems consisting of many active particles could spontaneously form clusters—even when the individual particles do not attract one another. The particles […]
Nanoscale rust: The future of magnets?
Phys.org October 5, 2023 Multiferroics have tremendous potential to revolutionize logic and memory devices through new functionalities and energy efficiencies. To better understand and enhance their ferroic orders and couplings an international team of researchers (Canada, USA – Lawrence Berkeley National Laboratory, Argonne National Laboratory) used epsilon iron oxide (ϵ-Fe2O3) as a model system with a simplifying single magnetic ion. Using 15, 20, and 30 nm nanoparticles, they found that a modified and size-dependent Fe–O hybridization changed the spin–orbit coupling. However, the size effects disappeared in the high-temperature phase where the strongest Fe–O hybridization occurred. By manipulating hybridization, they could […]