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Quantized magnetic vortices driven by electric current determine key electromagnetic properties of superconductors. While the dynamic behavior of slow vortices has been thoroughly investigated, the physics of ultrafast vortices under strong currents remains largely unexplored. Here, we use a nanoscale scanning superconducting quantum interference device to image vortices penetrating into a superconducting Pb film at rates of tens of GHz and moving with velocities of up to tens of km/s, which are not only much larger than the speed of sound but also exceed the pair-breaking speed limit of superconducting condensate. These experiments reveal formation of mesoscopic vortex channels which undergo cascades of bifurcations as the current and magnetic field increase. Our numerical simulations predict metamorphosis of fast Abrikosov vortices into mixed Abrikosov-Josephson vortices at even higher velocities. This work offers an insight into the fundamental physics of dynamic vortex states of superconductors at high current densities, crucial for many applications. Ultrafast vortex dynamics driven by strong currents define eletromagnetic properties of superconductors, but it remains unexplored. Here, Embon et al. use a unique scanning microscopy technique to image steady-state penetration of super-fast vortices into a superconducting Pb film at rates of tens of GHz and velocities up to tens of km/s.

Modulating superconductivityStrain can have considerable effects on the electronic properties of materials. For instance, the temperature at which a material becomes superconducting—the critical temperature—can be tuned by varying strain. Bachmann et al. used focused ion beam milling to fabricate microstructures of the superconductor CeIrIn5 on sapphire substrate. A difference in the thermal contraction coefficients of the two layers induced nonuniform strain upon cooling of the sample, leading to large gradients of the critical temperature. This approach can be used in other materials and may enable fabrication of superconducting circuitry without physical junctions.Science, this issue p. 221Although crystals of strongly correlated metals exhibit a diverse set of electronic ground states, few approaches exist for spatially modulating their properties. In this study, we demonstrate disorder-free control, on the micrometer scale, over the superconducting state in samples of the heavy-fermion superconductor CeIrIn5. We pattern crystals by focused ion beam milling to tailor the boundary conditions for the elastic deformation upon thermal contraction during cooling. The resulting nonuniform strain fields induce complex patterns of superconductivity, owing to the strong dependence of the transition temperature on the strength and direction of strain. These results showcase a generic approach to manipulating electronic order on micrometer length scales in strongly correlated matter without compromising the cleanliness, stoichiometry, or mean free path.

Nano‐patterned magnetic materials have opened new venues for the investigation of strongly correlated phenomena including artificial spin‐ice systems, geometric frustration, and magnetic monopoles, for technologically important applications such as reconfigurable ferromagnetism. With the advent of atomically thin 2D van der Waals (vdW) magnets, a pertinent question is whether such compounds could make their way into this realm where interactions can be tailored so that unconventional states of matter can be assessed. Here, it is shown that square islands of CrGeTe3 vdW ferromagnets distributed in a grid manifest antiferromagnetic correlations, essential to enable frustration resulting in an artificial spin‐ice. By using a combination of SQUID‐on‐tip microscopy, focused ion beam lithography, and atomistic spin dynamic simulations, it is shown that a square array of CGT island as small as 150 × 150 × 60 nm3 have tunable dipole–dipole interactions, which can be precisely controlled by their lateral spacing. There is a crossover between non‐interacting islands and significant inter‐island anticorrelation depending on how they are spatially distributed allowing the creation of complex magnetic patterns not observable at the isolated flakes. These findings suggest that the cross‐talk between the nano‐patterned magnets can be explored in the generation of even more complex spin configurations where exotic interactions may be manipulated in an unprecedented way. CrGeTe₃ nanoislands exhibiting tunable dipolar interactions resulting in an effective inter‐island antiferromagnetic coupling are demonstrated. The crossover between random and anticorrelated islands depends on their spatial distribution. The dipolar interaction enables the formation of complex magnetic patterns, which can be harnessed to generate more intricate spin configurations including artificial spin ice in van der Waals materials.

We developed a scanning superconducting quantum interference device (SQUID) microscope for imaging the magnetic field of geological samples in 2015 and have been continuously improving it. Since its introduction, the scanning SQUID microscope system has been used to measure various geological samples, including marine ferromanganese crusts, ferromanganese nodules, single-grain zircon crystals with magnetite inclusions, fault gauge samples, stalagmites with ultra-low magnetizations, ultramafic rocks containing strong magnetic minerals. In this paper, we detail the improvements made to the system and developments of measurement and post-processing software. We improved the implementation and the electrical connection of a SQUID chip on a sapphire rod. A new electrical connection combines aluminum wire bonding and silver paste, ensuring stable and low contact resistance across cooling cycles leading to constant sensitivity and stability of measurements. For the improved system, the shortest sensor-to-sample distance was measured at approximately 125 µm using a precision line current. Electromagnetic shielding and improvements on grounding were made, which contributed to improved signal-to-noise ratios. The introduction of the reference sensor allows subtraction of environmental magnetic field. The new feature of stacking at each measurement grid is effective in reducing noise for weakly magnetized samples. Additionally, the post-processing software has been developed. Various drift correction algorithms provide flexibility to the operator to deal with the situation including a narrow marginal area or a dirty marginal area contaminated with magnetic materials. Spike noises could be removed by median filter, and flux jumps could be corrected by another independent algorithm. Dipole fitting allows the operator to calculate the position, intensity, and direction of a dipole one by one. A list of dipoles is made, which could be subtracted from the magnetic images to clean up for further analyses. Upward continuation enables leveling of the magnetic images measured with different sensor-to-sample distances allowing meaningful comparison and subtraction between different demagnetization steps. Calculation of X- and Y-components from Z-component allows to obtain total magnetic field image, which could be used to locate magnetized materials easily.

Speleothems are ideal archives of environmental magnetism and paleomagnetism, since they retain continuous magnetic signals in stable conditions and can be used for reliable radiometric dating using U-series and radiocarbon methods. However, their weak magnetic signals hinder the widespread use of this archive in the field of geoscience. While previous studies successfully reconstructed paleomagnetic signatures and paleoenvironmental changes, the time resolutions presented were insufficient. Recently emerging scanning SQUID microscopy (SSM) in this field can image very weak magnetic fields while maintaining high spatial resolution that could likely overcome this obstacle. In this study, we employed SSM for high spatial resolution magnetic mapping on a stalagmite collected at Anahulu cave in Tongatapu Island, the Kingdom of Tonga. The average measured magnetic field after 5 mT alternating field demagnetization is ca. 0.27 nT with a sensor-to-sample distance of ~ 200 µm. A stronger magnetic field (average: ca. 0.62 nT) was observed above the grayish surface layer compared to that of the white inner part (average: ca. 0.09 nT) associated with the laminated structures of the speleothem at the submillimeter scale, which scanning resolution of the SSM in this study is comparable to the annual growth rates of the speleothem. The magnetization of the speleothem sample calculated from an inversion of isothermal remanent magnetization (IRM) also suggests that the magnetic mineral content in the surface layer is higher than the inner part. This feature was further investigated by low-temperature magnetometry. Our results show that the main magnetic carriers of the speleothem under study are magnetite and maghemite and it can contain hematite or ε-Fe2O3. The first-order reversal curve (FORC) measurements and the decomposition of IRM curves show that this speleothem contains a mixture of magnetic minerals with different coercivities and domain states. The contribution from maghemite to the total magnetization of the grayish surface layer was much higher than the white inner part. Such differences in magnetic mineralogy of the grayish surface layer from that of the inner part suggest that the depositional environment shifted and was likely changed due to the oxidative environment.

Two new pygmy squid from the Ryukyu archipelago, Japan, are described: Kodama jujutsu, n. gen., n. sp. and Idiosepius kijimuna, n. sp. They differ from all other nominal species in a combination of traits, including the number of tentacular club suckers, shape of the funnel-mantle locking-cartilage, modification of the male hectocotylus and the structure of the gladius and nuchal-locking cartilage, in addition to mitochondrial DNA markers (12S, 16S and COI). They are both known from Okinawa Island and there is some overlap in their distributions. In a molecular phylogeny that includes all nominal Idiosepiidae, Kodama jujutsu, n. gen., n. sp. is sister taxon to a clade containing Xipholeptos Reid & Strugnell, 2018 and Idiosepius Steenstrup, 1881. Xipholeptos and Idiosepius are sister taxa. Idiosepius spp. now includes seven nominal species. In addition, aspects of the behaviour of the new species are described.

Humboldt squid ( Dosidicus gigas ) is the most abundant cephalopod in the fishing industry, and its high nutritional and organoleptic properties make it a go-to food product for consumers. Therefore, developing new processing techniques seems imperative to minimize quality deterioration and provide products with appropriate characteristics. The study aimed to determine the effect of high-pressure impregnation (HPI) pretreatment on hot air-drying kinetics and the quality of Humboldt squid slices. Various pressures, times, and concentrations of osmotic solution during HPI were evaluated, followed by drying at 40 and 60 °C. The HPI pretreatment reduced the drying time by around 26% when dried at 40 °C, and only 18% when dried at⋅ 60 °C compared with unpretreated samples. The Weibull, Page, and Logarithmic models were considered for experimental drying curve modeling. Diffusion coefficient values varied from 3.82 to 6.59 × 10 −9 m 2 /s for all drying conditions. Moreover, the color, texture, and water-holding capacity were determined. Rehydration capacity values increased due to less damage to cellular tissue than the control (HPI-untreated dried samples). Also, scanning electron microscope (SEM) images showed a compacted structure of HPI-dried squid samples. Overall, HPI proved to be a beneficial pretreatment as it reduced drying time and improved the quality characteristics of Humboldt squid.

Scanning magnetic microscopes enable high-sensitivity mapping of magnetic fields in thin geological sections, facilitating submillimeter- to submicrometer-scale studies of paleomagnetism and rock magnetism. Magnetic fields of geological samples have been mapped using various sensors, including Hall-effect devices, magneto-impedance devices, superconducting quantum interference devices (SQUIDs), quantum diamond devices, and tunnel magneto-resistance (TMR) devices. This study proposes magnetic microscopy using high-sensitivity room-temperature TMR sensors developed for biomagnetic applications. The goal was to create high-performance magnetic microscopes that do not require labor-intensive techniques, such as cryogenic technology. An XYZ stage developed for a scanning SQUID microscope (SSM) was used to demonstrate and evaluate magnetic microscopy with TMR sensors. The original TMR sensors developed for biomagnetic sensing composed of serially connected TMR elements with a total length of 2684 μm were shortened to 1073 μm (Sensor #1) and 357 μm length (Sensor #2). Background measurements at 50 Hz show magnetic field sensitivities better than 200 nT/√Hz and 600 nT/√Hz at 1 Hz for Sensor #1 and Sensor #2, respectively. By averaging 10 points of the original 50 Hz sampling, magnetic field sensitivities are better than 30 nT/√Hz and 90 nT/√Hz at 1 Hz for Sensor #1 and Sensor #2, respectively. To demonstrate TMR sensors as magnetic microscopes, a vertically magnetized Hawaii basalt thin section was measured and compared with a SQUID-acquired magnetic field map. Magnetic scanning images obtained with TMR sensors on a 0.1-mm grid were compared with those of SSM after adjusting the lift-off by upward continuation and integrated along the length of the sensors. The results demonstrated that magnetic images for 1073-μm-long (357 μm-long) TMR sensors aligned along the y-axis and x-axis are consistent with those after upward continuation to 0.3 mm (0.25 mm) and 0.4 mm (0.25 mm) and convolution by 1 × 10 (1 × 4) and 10 × 1 (4 × 1) matrix, respectively. Overall, the high-sensitivity TMR sensors exhibited promising performance. Further improvements can be made by optimizing the sensors, preamplifiers, and measurement systems for magnetic microscopy to achieve an optimum target resolution. Graphical Abstract

This paper reports magnetic microscopy using high-sensitivity room-temperature tunnel magnetoresistance (TMR) devices for thin geological sections. The sensitivity region of the TMR sensor has dimensions of 178 µm (L) × 0.1 µm (W) × 100 µm (H), consisting of two TMR devices. Magnetic images were obtained for a vertically magnetized Hawaii basalt thin section in two sensor configurations, with the sensor length aligned parallel to the X- (lift-off = 174 μm) and Y-axes (lift-off = 200 μm), without introducing anisotropic distortion in the magnetic images. Although the magnetic images obtained with a scanning SQUID microscope (SSM) were similar, slight discrepancies were observed in the high-spatial-resolution region. A magnetic point source (50 μm × 50 μm) with a perpendicular magnetization film was prepared for evaluation. The SSM measurements showed a clear magnetic dipole at an angle of approximately 1° from the vertical direction. The FWHMs for both the SSM and TMR sensors increased linearly with lift-off. However, the peak magnetic fields, magnetic moments, and dipole tilts of the TMR sensor were significantly larger than those of the SSM sensor. This discrepancy may be due to the vertical extent of the active region of the TMR sensor, as well as due to sensor noise and drift.

Serratia sp. W4-01 was immobilized in chitosan-activated carbon beads and used for diesel oil removal. The type and concentration of chitosan, activated carbon content, and bead diameter were investigated as factors affecting diesel oil removal. The results showed that 2% ( w / v ) squid pen chitosan beads modified with 1% activated carbon ( w / v ) and with a 3-mm diameter had a good spherical shape and strength as well as diesel oil removal capability. The immobilized W4-01 cells removed more than 40% of diesel oil after 7 days when the initial diesel oil concentration was 100 to 400 mg L −1 , whereas 29–36% of diesel oil was removed after 14 days when the initial concentration was 800 to 1000 mg L −1 . Additionally, the immobilized cells maintained the ability to remove diesel oil over a pH range of 5–11. The addition of a biosurfactant increased the diesel oil removal from 62 to 75%. The reusability tests revealed that the ability of immobilized cells to remove diesel oil was enhanced after reuse, and 50–90% of diesel oil was removed during 2 to 12 reuse cycles. The stability and survival of W4-01 cells was confirmed by scanning electron microscopy and confocal laser scanning microscopy. The results of this study showed the potential use of W4-01 cells immobilized in chitosan-activated carbon beads for future applications in remediating diesel contamination.