Emergence of robust 2D skyrmions in SrRuO3 ultrathin film without the capping layer

Magnetic skyrmions have fast evolved from a novelty, as a realization of topologically protected structure with particle-like character, into a promising platform for new types of magnetic storage. Significant engineering progress was achieved with the synthesis of compounds hosting room-temperature skyrmions in magnetic heterostructures, with the interfacial Dzyaloshinskii-Moriya interactions (DMI) conducive to the skyrmion formation. Here we report findings of ultrathin skyrmion formation in a few layers of SrRuO3 grown on SrTiO3 substrate without the heavy-metal capping layer. Measurement of the topological Hall effect (THE) reveals a robust stability of skyrmions in this platform, judging from the high value of the critical field 1.57 Tesla (T) at low temperature. THE survives as the field is tilted by as much as 85 degrees at 10 Kelvin, with the in-plane magnetic field reaching up to 6.5 T. Coherent Bragg Rod Analysis, or COBRA for short, on the same film proves the rumpling of the Ru-O plane to be the source of inversion symmetry breaking and DMI. First-principles calculations based on the structure obtained from COBRA find significant magnetic anisotropy in the SrRuO3 film to be the main source of skyrmion robustness. These features promise a few-layer SRO to be an important new platform for skyrmionics, without the necessity of introducing the capping layer to boost the spin-orbit coupling strength artificially.Comment: Supplementary Information available upon reques

Emergence of robust 2D skyrmions in SrRuO3 ultrathin film without the capping layer

Magnetic skyrmions have fast evolved from a novelty, as a realization of topologically protected structure with particle-like character, into a promising platform for new types of magnetic storage. Significant engineering progress was achieved with the synthesis of compounds hosting room-temperature skyrmions in magnetic heterostructures, with the interfacial Dzyaloshinskii-Moriya interactions (DMI) conducive to the skyrmion formation. Here we report findings of ultrathin skyrmion formation in a few layers of SrRuO3 grown on SrTiO3 substrate without the heavy-metal capping layer. Measurement of the topological Hall effect (THE) reveals a robust stability of skyrmions in this platform, judging from the high value of the critical field 1.57 Tesla (T) at low temperature. THE survives as the field is tilted by as much as 85 degrees at 10 Kelvin, with the in-plane magnetic field reaching up to 6.5 T. Coherent Bragg Rod Analysis, or COBRA for short, on the same film proves the rumpling of the Ru-O plane to be the source of inversion symmetry breaking and DMI. First-principles calculations based on the structure obtained from COBRA find significant magnetic anisotropy in the SrRuO3 film to be the main source of skyrmion robustness. These features promise a few-layer SRO to be an important new platform for skyrmionics, without the necessity of introducing the capping layer to boost the spin-orbit coupling strength artificially.Comment: Supplementary Information available upon reques

Inflation Targeting and Relative Price Variability: What Difference Does Inflation Targeting Make?

This article studies the effects of inflation targeting (IT) on relative price variability (RPV) using a data set of twenty countries comprising both targeters and nontargeters. We find that a decline in mean inflation after IT adoption is not necessarily associated with a similar fall in RPV and that what matters most for the structural changes in RPV is the initial inflation regime prior to the adoption of IT rather than IT adoption itself. IT adoption impacts the shape of the underlying relationship between inflation and RPV in countries with initially high inflation rates, moving it from monotonie to the U-shaped profile observed consistently for countries with low-inflation regimes. The minimum point of this U-shaped curve is indicative of the public\u27s expectations of inflation and is very close to the announced target for inflation in most of the countries we study

Dark rearing alters the development of GABAergic transmission in visual cortex

We studied the role of sensory experience in the maturation of GABAergic circuits in the rat visual cortex. Between the time at which the eyes first open and the end of the critical period for experience-dependent plasticity, the total GABAergic input converging into layer II/III pyramidal cells increases threefold. We propose that this increase reflects changes in the number of quanta released by presynaptic axons. Here, we show that the developmental increase in GABAergic input is prevented in animals deprived of light since birth but not in animals deprived of light after a period of normal experience. Thus, sensory experience appears to play a permissive role in the maturation of intracortical GABAergic circuits. Key words: synaptic inhibition; critical period; IPSC; EPSC; plasticity; sensory experience Sensory experience during the postnatal critical period is essentia

Gas-Filled Phospholipid Nanoparticles Conjugated with Gadolinium Play a Role as a Potential Theragnostics for MR-Guided HIFU Ablation

To develop a long-circulating theragnostics, meaning therapeutics and diagnostics for MR-guided HIFU ablation, we designed and prepared Gd-C5F12-phospholipid nanobubbles (PLNs) 30–100 nm in diameter. The biochemical and physical characterization of Gd-C5F12-PLNs were performed. Since Gd-C5F12-PLN-50 (Φ = 50 nm) and Gd-C5F12-PLN-100 (Φ = 100 nm) enhanced the hyperthermal effect of HIFU size- and concentration-dependently in a tissue-mimicking phantom, its circulation, distribution, tumor accumulation and tumor ablation were examined in tumor-bearing mice. The plasma-half life of Gd-C5F12-PLNs was longer than 1.5 hrs. Gd-C5F12-PLNs mainly accumulated in the liver and the spleen, suggesting that they are slowly secreted through the hepatobiliary pathway. Monitored by the T1 signal intensity of MR, Gd-C5F12-PLNs accumulated in tumor tissues for 8 hours in mice. HIFU with Gd-C5F12-PLN-100 showed the increased tumor ablation area as compared with HIFU alone. The results suggest that Gd-C5F12-PLNs exhibit a potential theragnostics for MR-guided HIFU ablation

Enhanced spin density wave in LaOFeSb

We predict atomic, electronic, and magnetic structures of a hypothetical compound LaOFeSb by first-principles density-functional calculations. It is shown that LaOFeSb prefers a stripe-type antiferromagnetic phase (i.e., spin density wave (SDW) phase) to the non-magnetic (NM) phase, with a larger Fe spin moment and greater SDW-NM energy difference than those of LaOFeAs. The SDW phase is found to favor the orthorhombic structure while the tetragonal structure is more stable in the NM phase. In the NM-phase LaOFeSb, the electronic bandwidth near the Fermi energy is reduced compared with LaOFeAs, indicating smaller orbital overlap between Fe $d$ states and subsequently enhanced intra-atomic exchange coupling. The calculated Fermi surface in the NM phase consists of three hole and two electron sheets, and shows increased nesting between two hole and two electron sheets compared with LaOFeAs. Monotonous changes found in our calculated material properties of LaOFePn (Pn=P, As, and Sb), along with reported superconducting properties of doped LaOFeP and LaOFeAs, suggest that doped LaOFeSb may have a higher superconducting transition temperature.Comment: 5 pages with 3 figures and 1 table, double colum

Towards Unbiased Evaluation of Detecting Unanswerable Questions in EHRSQL

Incorporating unanswerable questions into EHR QA systems is crucial for testing the trustworthiness of a system, as providing non-existent responses can mislead doctors in their diagnoses. The EHRSQL dataset stands out as a promising benchmark because it is the only dataset that incorporates unanswerable questions in the EHR QA system alongside practical questions. However, in this work, we identify a data bias in these unanswerable questions; they can often be discerned simply by filtering with specific N-gram patterns. Such biases jeopardize the authenticity and reliability of QA system evaluations. To tackle this problem, we propose a simple debiasing method of adjusting the split between the validation and test sets to neutralize the undue influence of N-gram filtering. By experimenting on the MIMIC-III dataset, we demonstrate both the existing data bias in EHRSQL and the effectiveness of our data split strategy in mitigating this bias.Comment: DPFM Workshop, ICLR 202