Epitaxial LaFeAsOF thin films grown by pulsed laser deposition

Superconducting and epitaxially grown LaFeAsOF thin films were successfully prepared on (001)-oriented LaAlO3 substrates using pulsed laser deposition. The prepared thin films show exclusively a single in-plane orientation with epitaxial relation (001)[100] parallel to (001)[100] and a FWHM value of 1deg. Furthermore, resistive measurement of the superconducting transition temperature revealed a Tc90 of 25K with a high residual resistive ratio of 6.8. The applied preparation technique, standard thin film pulsed laser deposition at room temperature in combination with a subsequent post annealing process, is suitable for fabrication of high quality LaFeAsO1-xFx thin films. A high upper critical field of 76.2 T was evaluated for magnetic fields applied perpendicular to the c-axis and the anisotropy was calculated to be 3.3 assuming single band superconductivity.Comment: 6 pages, 4 Figure

Selective mass enhancement close to the quantum critical point in BaFe₂(As₁₋ₓ Pₓ )₂

A quantum critical point (QCP) is currently being conjectured for the BaFe₂(As₁₋ₓ Pₓ )₂ system at the critical value xc ≈ 0.3. In the proximity of a QCP, all thermodynamic and transport properties are expected to scale with a single characteristic energy, given by the quantum fluctuations. Such a universal behavior has not, however, been found in the superconducting upper critical field Hc2. Here we report Hc2 data for epitaxial thin films extracted from the electrical resistance measured in very high magnetic fields up to 67 Tesla. Using a multi-band analysis we find that Hc₂ is sensitive to the QCP, implying a significant charge carrier effective mass enhancement at the doping-induced QCP that is essentially band-dependent. Our results point to two qualitatively different groups of electrons in BaFe₂(As₁₋ₓ Pₓ )₂ . The first one (possibly associated to hot spots or whole Fermi sheets) has a strong mass enhancement at the QCP, and the second one is insensitive to the QCP. The observed duality could also be present in many other quantum critical systems

A disorder-sensitive emergent vortex phase identified in high- T csuperconductor (Li,Fe)OHFeSe

The magneto-transport properties are systematically measured under c-direction fields up to 33 T for a series of single-crystal films of intercalated iron-selenide superconductor (Li,Fe)OHFeSe. The film samples with varying degree of disorder are grown hydrothermally. We observe a magnetic-field-enhanced shoulder-like feature in the mixed state of the high-T c (Li,Fe)OHFeSe films with weak disorder, while the feature fades away in the films with enhanced disorder. The irreversibility field is significantly suppressed to lower temperatures with the appearance of the shoulder feature. Based on the experiment and model analysis, we establish a new vortex-phase diagram for the weakly-disordered high-T c (Li,Fe)OHFeSe, which features an emergent dissipative vortex phase intermediate between the common vortex glass and liquid phases. The reason for the emergence of this intermediate vortex state is further discussed based on related experiments and models. © 2022 IOP Publishing Ltd.Deutsche Forschungsgemeinschaft, DFG: HA6407/4-1; National Natural Science Foundation of China, NSFC: 11834016, 11874359, 11888101, 12061131005; Chinese Academy of Sciences, CAS: XDB25000000, XDB33010200; National Key Research and Development Program of China, NKRDPC: 2017YFA0303003; Ministry of Science and Higher Education of the Russian Federation: АААА-А18-118020190104-3D Li thanks Dr W Hu, professors Z X Shi, and H H Wen for helpful discussions. This work was supported by National Key Research and Development Program of China (Grant No. 2017YFA0303003), the National Natural Science Foundation of China (Grant Nos. 12061131005, 11834016, 11888101, and 11874359), the Strategic Priority Research Program of Chinese Academy of Sciences (XDB33010200 and XDB25000000). J Hänisch thanks for the financial support provided by the Deutsche Forschungsgemeinschaft (DFG) through project HA6407/4-1. E F Talantsev thanks for the financial support provided by the Ministry of Science and Higher Education of Russia (theme ‘Pressure’ No. АААА-А18-118020190104-3) and by Act 211 Government of the Russian Federation, Contract No. 02.A03.21.0006. A portion of this work was performed on the Steady High Magnetic Field Facilities, High Magnetic Field Laboratory, Chinese Academy of Sciences, and supported by the High Magnetic Field Laboratory of Anhui Province

Pathogens and polymers: Microbe–host interactions illuminate the cytoskeleton

Intracellular pathogens subvert the host cell cytoskeleton to promote their own survival, replication, and dissemination. Study of these microbes has led to many discoveries about host cell biology, including the identification of cytoskeletal proteins, regulatory pathways, and mechanisms of cytoskeletal function. Actin is a common target of bacterial pathogens, but recent work also highlights the use of microtubules, cytoskeletal motors, intermediate filaments, and septins. The study of pathogen interactions with the cytoskeleton has illuminated key cellular processes such as phagocytosis, macropinocytosis, membrane trafficking, motility, autophagy, and signal transduction

The Long-term impact of the location of concentration camps on radical-right voting in Germany

Of all atrocities committed by state actors in 20th century Europe, the systematic killings by Nazi Germany were arguably the most severe and best documented. While several studies have investigated the impact of the presence of concentration camps on surrounding communities in Germany and the occupied territories in terms of redistribution of wealth and property, the local-level impact on voting behaviour has not yet been explored. We investigated the impact of spatial proximity to a concentration camp between 1933 and 1945 on the likelihood of voting for far-right parties in the 2013 and 2017 federal elections. We find that proximity to a former concentration camp is associated with a higher vote share of such parties. A potential explanation for this finding could be a ‘memory satiation effect’, according to which voters who live in close proximity to former camps and are more frequently confronted with the past are more receptive to revisionist historical accounts questioning the centrality of the Holocaust in the German culture of remembrance

Stage-specific transcription activator ESB1 regulates monoallelic antigen expression in Trypanosoma brucei

Variant surface glycoprotein (VSG) coats bloodstream form Trypanosoma brucei parasites and monoallelic VSG expression underpins the antigenic variation necessary for pathogenicity. One of thousands of VSG genes is transcribed by RNA polymerase I (Pol I) in a singular nuclear structure called the expression site body (ESB) but how monoallelic VSG transcription is achieved remains unclear. Using a localisation screen of 153 proteins, we found one, ESB-specific protein 1 (ESB1), which localised only to the ESB and is expressed only in VSG-expressing life cycle stages. ESB1 associates with DNA near the active VSG promoter and is necessary for VSG expression, with overexpression activating inactive VSG promoters. Mechanistically, ESB1 is necessary for recruitment of a subset of ESB components, including Pol I, revealing the ESB has separately assembled sub-domains. As many trypanosomatid parasites have divergent ESB1 orthologs yet do not undergo antigenic variation, ESB1 likely represents an important class of transcription regulators