Chiral Majorana Modes via Proximity to a Twisted Cuprate Bilayer

We propose a novel heterostructure to achieve chiral topological superconductivity in 2D. A substrate with a large Rashba spin-orbit coupling energy is brought in proximity to a twisted bilayer of thin films exfoliated from a high-temperature cuprate superconductor. The combined system is then exposed to an out-of-plane magnetic field. The rare $d + id$ pairing symmetry expected to occur in such a system allows for nontrivial topology; specifically, in contrast to the case of the twisted bilayer in isolation, the substrate induces an odd Chern number. The resulting phase is characterized by the presence of a Majorana zero mode in each vortex.Comment: 7 pages, 6 figure

Visualization of Topological Boundary Modes Manifesting Topological Nodal-Point Superconductivity

The extension of the topological classification of band insulators to topological semimetals gave way to the topology classes of Dirac, Weyl, and nodal line semimetals with their unique Fermi arc and drum head boundary modes. Similarly, there are several suggestions to employ the classification of topological superconductors for topological nodal superconductors with Majorana boundary modes. Here, we show that the surface 1H termination of the transition metal dichalcogenide compound 4Hb-TaS2, in which 1T-TaS2 and 1H-TaS2 layers are interleaved, has the phenomenology of a topological nodal point superconductor. We find in scanning tunneling spectroscopy a residual density of states within the superconducting gap. An exponentially decaying bound mode is imaged within the superconducting gap along the boundaries of the exposed 1H layer characteristic of a gapless Majorana edge mode. The anisotropic nature of the localization length of the edge mode aims towards topological nodal superconductivity. A zero-bias conductance peak is further imaged within fairly isotropic vortex cores. All our observations are accommodated by a theoretical model of a two-dimensional nodal Weyl-like superconducting state, which ensues from inter-orbital Cooper pairing. The observation of an intrinsic topological nodal superconductivity in a layered material will pave the way for further studies of Majorana edge modes and its applications in quantum information processing.N.A., H.B., and B.Y acknowledge the German–Israeli Foundation for Scientific Research and Development (GIF grant no. I-1364-303.7/2016). H.B. and N.A. acknowledge the European Research Council (ERC, project no. TOPO NW), B.Y. acknowledges financial support by the Willner Family Leadership Institute for the Weizmann Institute of Sci- ence, the Benoziyo Endowment Fund for the Advancement of Science, the Ruth and Her- man Albert Scholars Program for New Scientists, and the Israel Science Foundation (ISF 1251/19). G.A.F. gratefully acknowledges partial support from the National Science Foun- dation through NSF Grant no. DMR-1720595, and DMR-1949701. Y.O. acknowledges partial support through the ERC under the European Union’s Horizon 2020 research and innovation programme (grant agreement LEGOTOP No 788715), the ISF Quantum Science and Technology (2074/19), the BSF and NSF (2018643), and the CRC/Transregio 183. A.K. acknowledges the Israel Science Foundation (ISF 320/17).Center for Dynamics and Control of Material

Gypsies in Germany—German Gypsies? Identity and Politics of Sinti and Roma in Germany

In this essay we introduce the population referred to as ‘German Gypsies.’ We then proceed to examine forms of organization and modern representation of identity, focusing especially on the dichotomy between two distinct self-images: the first, of a minority based in German territory and culture yet distinct from mainstream German society; the second, of a group that belongs to a transnational ethnic minority dispersed both within and outside of the German context. We will try to assess the i..

Cranialization of the frontal sinus for secondary mucocele prevention following open surgery for benign frontal lesions.

OBJECTIVE: To compare frontal sinus cranialization to obliteration for future prevention of secondary mucocele formation following open surgery for benign lesions of the frontal sinus. STUDY DESIGN: Retrospective case series. SETTING: Tertiary academic medical center. PATIENTS: Sixty-nine patients operated for benign frontal sinus pathology between 1994 and 2011. INTERVENTIONS: Open excision of benign frontal sinus pathology followed by either frontal obliteration (n = 41, 59%) or frontal cranialization (n = 28, 41%). MAIN OUTCOME MEASURES: The prevalence of post-surgical complications and secondary mucocele formation were compiled. RESULTS: Pathologies included osteoma (n = 34, 49%), mucocele (n = 27, 39%), fibrous dysplasia (n = 6, 9%), and encephalocele (n = 2, 3%). Complications included skin infections (n = 6), postoperative cutaneous fistula (n = 1), telecanthus (n = 4), diplopia (n = 3), nasal deformity (n = 2) and epiphora (n = 1). None of the patients suffered from postoperative CSF leak, meningitis or pneumocephalus. Six patients, all of whom had previously undergone frontal sinus obliteration, required revision surgery due to secondary mucocele formation. Statistical analysis using non-inferiority test reveal that cranialization of the frontal sinus is non-inferior to obliteration for preventing secondary mucocele formation (P<0.0001). CONCLUSION: Cranialization of the frontal sinus appears to be a good option for prevention of secondary mucocele development after open excision of benign frontal sinus lesions