Towards engineering the perfect defect in high-performing permanent magnets

Permanent magnets draw their properties from a complex interplay, across multiple length scales, of the composition and distribution of their constituting phases, that act as building blocks, each with their associated intrinsic properties. Gaining a fundamental understanding of these interactions is hence key to decipher the origins of their magnetic performance and facilitate the engineering of better-performing magnets, through unlocking the design of the "perfect defects" for ultimate pinning of magnetic domains. Here, we deployed advanced multiscale microscopy and microanalysis on a bulk Sm2(CoFeCuZr)17 pinning-type high-performance magnet with outstanding thermal and chemical stability. Making use of regions with different chemical compositions, we showcase how both a change in the composition and distribution of copper, along with the atomic arrangements enforce the pinning of magnetic domains, as imaged by nanoscale magnetic induction mapping. Micromagnetic simulations bridge the scales to provide an understanding of how these peculiarities of micro- and nanostructure change the hard magnetic behaviour of Sm2(CoFeCuZr)17 magnets. Unveiling the origins of the reduced coercivity allows us to propose an atomic-scale defect and chemistry manipulation strategy to define ways toward future hard magnets

Stories from the field:Women's networking as gender capital in entrepreneurial ecosystems

Women are underrepresented in successful entrepreneurial ecosystems and the creation of women-only entrepreneurial networks has been a widespread policy response. We examine the entrepreneurial ecosystem construct and suggest that it, and the role networks play in entrepreneurial ecosystems, can be analysed in terms of Bourdieu's socio-analysis as field, habitus and capital. Specifically, we develop the notion of gender capital as the skill set associated with femininity or from simply being recognized as feminine. We apply this to the development of women's entrepreneurial networks as a gender capital enhancing initiative. Using data from qualitative interviews with network coordinators and women entrepreneurs we reflect on the extent to which formally established women-only networks generate gender capital for their members and improve their ability to participate in the entrepreneurial ecosystem. The paper concludes by drawing out the implications of our analysis for theory, entrepreneurial practice and economic development policy

Transport properties of Bi2Sr2Ca2Cu3O10+sigma bicrystal grain boundary Josephson junctions and SQUIDs

Josephson junctions and SQUIDs on 36.8° SrTiO3 bicrystal substrates were prepared from epitaxial Bi2Sr2Ca2Cu3O10+δ thin films with critical temperatures around 95K. The current-voltage characteristics are well described by the resistively and capacitively shunted junction model. IcRn products of 50µV at 77K and 0.7mV at 4.2K have been reached. The Ic(B) dependence is symmetric to B = 0 with an Ic suppression of 90% in the first minimum. Nevertheless it turns out, that the junctions are inhomogeneous on a µm scale. SQUID modulations observed at 78K indicate a flux-voltage transfer function of 2.7µV/Φ0 at this temperature

Transport properties of Bi2Sr2Ca2Cu3O10+δ Bicrystal Grain Boundary Josephson Junctions and SQUIDs

Josephson junctions and SQUIDs on 36.8° SrTiO3 bicrystal substrates were prepared from epitaxial Bi2Sr2Ca2Cu3O10+δ thin films with critical temperatures around 95K. The current-voltage characteristics are well described by the resistively and capacitively shunted junction model. IcRn products of 50µV at 77K and 0.7mV at 4.2K have been reached. The Ic(B) dependence is symmetric to B = 0 with an Ic suppression of 90% in the first minimum. Nevertheless it turns out, that the junctions are inhomogeneous on a µm scale. SQUID modulations observed at 78K indicate a flux-voltage transfer function of 2.7µV/Φ0 at this temperature

Bi2Sr2Ca2Cu3O10+δ based Josephson junctions and SQUIDs

Josephson junctions and SQUIDs on SrTiO3 bicrystal substrates were prepared from epitaxial Bi2Sr2Ca2Cu3O10 ? thin films with critical temperatures around 95K. The current-voltage characteristics are well described by the resistively and capacitively shunted junction model.I c R n products of 50?V at 77K and 0.7m V at 4.2K have been reached. TheI c (B) dependence is symmetric toB=0 with anI c suppression of 90% in the first minimum. Nevertheless it turns out, that the junctions are inhomogeneous on a ?m scale. The flux-voltage transfer function of a SQUID reached 2.7?V/?0 at 78K

Josephson junctions and SQUIDs based on artificial grain boundaries in Bi2Sr2Ca2Cu3O10-thin films

High quality thin films of Bi2Sr2Ca2Cu3O10 with critical temperatures of 95K were used to prepare grain boundary Josephson junctions on commercial 36.8 degrees SrTiO3-bicrystal substrates. IcRn- products of 50 (mu) V at 77 K and 0.7 mV at 4.2 have been reached. For temperatures higher than 50K the current- voltage curves of the junctions can be well described by the resistively shunted junction model and show no hysteresis. From the hysteretic behavior at low temperature we estimate a junction capacitance of 21 (mu) F/cm2. The Fraunhofer pattern of the critical current in an external applied field shows, that the junctions are inhomogeneous on a micrometers scale. The SQUID modulation of a 30 X 40 micrometers 2 wide superconducting loop containing two 10 micrometer wide junctions yields a flux-voltage transfer function of 2.7 (mu) V/(Phi) 0 at 78K

Josephson junctions and superconducting field effect transistors based on epitaxial Bi2Sr2Can-1CunO2(n+2) thin films

Josephson junctions based on thin films of the Bi2Sr2Ca2Cu3O10 ? compound show IcRn products compatible with YBa2Cu3O7?? samples. Using quasiparticle tunneling experiments we found evidence for a superconductor?insulator?superconductor tunneling process via localized states in the barrier. The Bi2Sr2CaCu2O8 ? compound is investigated regarding possible applications in superconducting field effect devices. We present thin films of four unit cells thickness that are superconducting at 58 K. An inverted metal?insulator?superconductor structure was prepared. From the modulation of the normal state resistance we estimate a carrier density of 7×1019 cm?3 for a superconducting sample. The shift of the transition temperature was 1 K/V. The modulation of the I?V characteristics was demonstrated