The discovery of superconductivity in a d 9−δ nickelate has inspired disparate theoretical perspectives regarding the essential physics of this class of materials. A key issue is the magnitude of the magnetic superexchange, which relates to whether cuprate-like high-temperature nickelate superconductivity could be realized. We address this question using Ni L-edge and O K-edge spectroscopy of the reduced d 9−1=3 trilayer nickelates R 4 Ni 3 O 8 (where R ¼ La, Pr) and associated theoretical modeling. A magnon energy scale of ∼80 meV resulting from a nearest-neighbor magnetic exchange of J ¼ 69ð4Þ meV is observed, proving that d 9−δ nickelates can host a large superexchange. This value, along with that of the Ni-O hybridization estimated from our O K-edge data, implies that trilayer nickelates represent an intermediate case between the infinite-layer nickelates and the cuprates. Layered nickelates thus provide a route to testing the relevance of superexchange to nickelate superconductivity.

We report the synthesis of single-crystal La0.67Sr0.33MnO3 (LSMO) freestanding films with different crystal orientations. By using pulsed laser deposition, water soluble perovskite-like sacrificial layers Sr3Al2O6 (SAO) followed by LSMO films are grown on differently oriented SrTiO3 substrates. Freestanding LSMO films with different orientations are obtained by etching the SAO in pure water. All the freestanding films show room-temperature ferromagnetism and metallicity, independent of the crystal orientation. Intriguingly, the Curie temperature (TC) of the freestanding films is increased due to strain relaxation after releasing from the substrates. Our results provide an additional degree of freedom to tailor the properties of freestanding perovskite oxide heterostructures by crystal orientation and an opportunity to further integrate different oriented films together.

Purpose: To investigate the effects of dose reduction on image quality and lesion detectability of oncological 18 F-FDG total-body PET/CT in paediatric oncological patients, and explore the minimum threshold of administered tracer activity. Methods: A total of 33 paediatric patients (weight, 8.5-58.5 kg; age 0.8-17.6 years) underwent total-body PET/CT using uEXPLORER scanner with an 18 F-FDG administered dose of 3.7 MBq/kg and an acquisition time of 600 s were retrospectively enrolled. Low-dose images (0.12 -1.85 MBq/kg) were simulated by truncating the list-mode PET data to reducing count density. Subjective image quality was rated on a 5point scale. Semi-quantitative uptake metrics for low-dose images were assessed using region-of-interest (ROI) analysis of healthy liver and suspected lesions and were compared to full-dose images. The microlesion detectability was compared among the dose-dependent PET images.Results: Our analysis shows that su cient subjective image quality and lesion conspicuity could be maintained down to 1/30th (0.12 MBq/kg) of the administered dose of 18 F-FDG, where good image quality scores were given to 1/2-and 1/10-dose groups. The image noise was signi cantly more deranged than the overall quality and lesion conspicuity in 1/30-to 1/10-dose groups (all P < 0.05). With reduced doses, quantitative analysis of ROIs showed that SUV max and SD in the liver increased gradually (P < 0.05), but SUV max in the lesions and lesion-to-background ratio (LBR) showed no signi cant deviation down to 1/30-dose. 100% of the 18 F-FDG-avid micro-lesions identi ed in full-dose images were localised down to 1/15-dose images; while 97% of the lesion were localized in 1/30-dose images. Conclusion:The total-body PET/CT might signi cantly decrease the administered dose upon maintaining the image quality and diagnostic performance of micro-lesions in paediatric patients. Data suggests that using total-body PET/CT, optimal image quality could be achieved with an administered dose-reduction down to 1/10-dose (0.37 MBq/kg).

Articles you may be interested inSeeking to quantify the ferromagnetic-to-antiferromagnetic interface coupling resulting in exchange bias with various thin-film conformations J. Appl. Phys. 116, 053911 (2014); 10.1063/1.4892177Effect of antiferromagnetic layer thickness on exchange bias, training effect, and magnetotransport properties in ferromagnetic/antiferromagnetic antidot arrays

In-plane exchange bias (EB) in [Pt/Co]n/NiFe/NiO heterostructures with orthogonal easy axes is investigated. The reversible in-plane EB effect at the ferromagnetic (FM)/FM [Pt/Co]n/NiFe interface allows one to manipulate the value and direction of the EB of the heterostructures, which can be induced by applying a magnetic field larger than the perpendicular anisotropy field of the [Pt/Co]n multilayers. The difference between the EB of the heterostructures after field cooling and zero field cooling disappears at 120 K, which may originate from the exchange coupling at the FM/antiferromagnetic (AFM) NiFe/NiO interface. The NiFe thickness dependence of the bias field of the EB exhibits behavior similar to that in conventional FM/AFM bilayers. The EB can be maintained even at room temperature.

Flexible magnetic materials with robust and controllable perpendicular magnetic anisotropy (PMA) are highly desirable for developing flexible high-performance spintronic devices. However, it is still challenge to fabricate PMA films on polymers directly. Here, we report a facile method for synthesizing single-crystal freestanding SrRuO3 membranes with controlled crystal structure and orientation using water-soluble Ca3-xSrxAl2O6 sacrificial layers. Through cooperative effect of crystal structure and orientation, flexible membranes reveal highly tunable magnetic anisotropy from in-plane to out-of-plane with a remarkable PMA energy of 7 × 106 erg·cm−3. First-principle calculations reveal that the underlying mechanism of PMA modulation is intimately correlated with structure-controlled Ru 4d-orbital occupation, as well as spin-orbital matrix element differences, dependent on the crystal orientation. In addition, even after 10,000 bending cycles, the PMA keeps stable, indicating a robust magnetism reliability in the prepared films. This work provides a feasible approach to prepare the flexible oxide films with strong and controllable PMA.

Due to climate variation and global warming, utilization of renewable energy becomes increasingly imperative. Rechargeable potassium-ion batteries (PIBs) have lately attracted much attention due to their earth-abundance and cost-effectiveness. Because soft carbon materials are cheap, abundant, and safe, extensive feasible research studies have indicated that they could become promising anode materials for PIBs. In spite of gaining achievements, fundamental questions regarding effects of the basic structure unit inside soft carbon on potassium storage potential have not been sufficiently addressed yet. Here, a series of soft carbon pyrolyzed from 900 to 2900 °C were systematically and quantitatively characterized by combining Raman spectroscopy, near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, X-ray pair distribution function analysis, and advanced evaluation of wide-angle X-ray scattering data. All these characterizations reveal structural details of soft carbon with increasing pyrolysis temperature. Our results show that the potassium storage behavior, especially the potential plateau is closely correlated to non-uniformity in interlayer distance and defect concentration in soft carbon, which is further confirmed by reverse Monte Carlo (RMC) modeling and density functional theory calculation. On the basis of these results, optimizing strategies are discussed to design an advanced soft carbon anode. This work provides significant insights into the structure engineering of soft carbon for high-performance rechargeable PIBs.

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