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This paper explores the effect of agricultural policies on industrialization and economic development over the long-run. I analyze the differential effect of the \textit{Battle for Grain}, implemented by the Italian Fascist regime to achieve self-sufficiency in wheat production, on the development path across areas of Italy. Employing time variation, along with cross-sectional variation in the suitability of land for the implementation of the advanced wheat production technologies, I find that the policy had unintended positive effects on industrialization and economic prosperity which persisted until the contemporary period. Furthermore, I find that the positive effect of the \textit{Battle for Grain} on human capital accumulation was instrumental in this process, suggesting that the complementarity between human capital and agricultural technology may be a critical mechanism through which agricultural productivity may enhance the development of non-agricultural sectors.

We investigate the link between the 1918 Great Influenza and regional economic growth in Italy, a country in which the measures implemented by public authorities to contain the contagion were limited or ineffective. The pandemic caused 600,000 deaths in Italy: 1.2% of the population. Going from regions with the lowest mortality to those with the highest mortality is associated to a decline in per capita GDP growth of 6.5%, which dissipated within 3 years. Our estimates provide an upper bound of the adverse effect of pandemics on regional economic growth in the absence of non-pharmaceutical public-health interventions.

High critical temperature superconductors (HTS) based devices can have impact in the study of the phase dynamics of Josephson junctions (JJs) thanks to the wide range of junction parameters they offer and to their unconventional properties. Measurements of current-voltage characteristics and of switching current distributions constitute a direct way to classify different regimes of the phase dynamics and of the transport, also in nontrivial case of the moderately damped regime (MDR). MDR is going to be more and more common in JJs with advances in nanopatterning superconductors and synthesizing novel hybrid systems. Distinctive signatures of macroscopic quantum tunneling and of thermal activation in presence of different tunable levels of dissipation have been detected in YBCO grain boundary JJs. Experimental data are supported by Monte Carlo simulations of the phase dynamics, in a wide range of temperatures and dissipation levels. This allows us to quantify dissipation in the MDR and partially reconstruct a phase diagram as guideline for a wide range of moderately damped systems. (C) 2014 Elsevier B.V. All rights reserved.

Concepts and experimental procedures to obtain different types of YBa 2 Cu 3 O 7 grain boundaries Josephson junction through the biepitaxial technique have been developed. Various seed layers (MgO, CeO 2 and SrTiO 3) and substrates (MgO, SrTiO 3) have been used providing, for the biepitaxial technique, additional flexibility in circuit design. A detailed investigation on transport properties evidenced good performances for both junctions and superconducting quantum interference devices. Experimental evidence is given of a conventional magnetic field behavior in 45° tilt Artificial Grain Boundary (AGB) for which no π-loops are predicted along the interface.

(110) and (103) YBa 2 Cu 3 O 7 films have been grown onto exact and vicinal (110) SrTiO 3 substrates, and on vicinal (110) MgO substrates with a SrTiO 3 buffer layer. The samples are carefully characterised by reciprocal space mapping with x-ray diffraction, in order to investigate the features of the typical double domain of (110) and (103) YBa 2 Cu 3 O 7 structure. It is demonstrated that vicinal cut substrates allow to select one film/substrate epitaxial relation. The growth properties of these thin films deposited on vicinal surfaces are discussed.

We suggest a spin filter scheme using T-stub nanometric crossjunctions patterned in two dimensional electron gases (2DEGs) in the presence of spin orbit interaction (SOI). We compare the effects of SOI arising from vertical confinement of charge carriers in the well, Rashba or alpha-SOI, with SOI generated by lateral confinement of the wire, beta-SOI. We show that beta coupling can be more effective in generating a spin polarized current as compared to alpha-SOI. We also compare the efficiency of the T-stub filter with the one of the X shaped cross junction.

We have developed a fabrication process that allows us to realize pure YBCO nanowires displaying robust superconductivity at widths w as low as 160 nm. We can modify the process in order to maintain a Au protective layer. This allows us to scale our nanowires even further to widths as low as 50 nm. We have studied how the presence of vortices and the occurrence of phase slips affect the transport properties of nanowires in the width range xi < w < lambda, being xi the coherence length and lambda the magnetic penetration depth. Magnetoresistance curves present features which are related to the effect of screening currents. Vortex entry barrier is found to scale with the width. Our findings confirm that for widths xi < w < lambda nanowires are better protected against phase slips and vortex flow. (C) 2014 Elsevier B.V. All rights reserved.

Since the discovery of high-temperature superconductors (HTSs), most efforts of researchers have been focused on the fabrication of superconducting devices capable of immobilizing vortices, hence of operating at enhanced temperatures and magnetic fields. Recent findings that geometric restrictions may induce self-arresting hypervortices recovering the dissipation-free state at high fields and temperatures made superconducting strips a mainstream of superconductivity studies. Here we report on the geometrical melting of the vortex lattice in a wide YBCO submicron bridge preceded by magnetoresistance (MR) oscillations fingerprinting the underlying regular vortex structure. Combined magnetoresistance measurements and numerical simulations unambiguously relate the resistance oscillations to the penetration of vortex rows with intermediate geometrical pinning and uncover the details of geometrical melting. Our findings offer a reliable and reproducible pathway for controlling vortices in geometrically restricted nanodevices and introduce a novel technique of geometrical spectroscopy, inferring detailed information of the structure of the vortex system through a combined use of MR curves and large-scale simulations.

Proximity-effect and resistance magneto-fluctuations measurements in submicron Nd1.2Ba1.8Cu3Oz (NBCO) nano-loops are reported to investigate coherent charge transport in the non-superconducting state. We find an unexpected inhibition of cooper pair transport, and a destruction of the induced superconductivity, by lowering the temperature from 6K to 250mK. This effect is accompanied by a significant change in the conductance-voltage characteristics and in the zero bias conductance response to the magnetic field pointing to the activation of a strong pair breaking mechanism at lower temperature. The data are discussed in the framework of mesoscopic effects specific to superconducting nanostructures, proximity effect and high temperature superconductivity., to appear on new journal of Physics

YBaCuO nanowires were reproducibly fabricated down to widths of 50 nm. A Au/Ti cap layer on YBCO yielded high electrical performance up to temperatures above 80 K in single nanowires. Critical current density of tens of MA/cm2 at T = 4.2 K and of 10 MA/cm2 at 77 K were achieved that survive in high magnetic fields. Phase-slip processes were tuned by choosing the size of the nanochannels and the intensity of the applied external magnetic field. Data indicate that YBCO nanowires are rather attractive system for the fabrication of efficient sensors, supporting the notion of futuristic THz devices., 8 pages, 3 figures. Accepted for publication in Superconductor Science and Technology

An innovative fabrication procedure has been developed to obtain YBa(2)Cu(3)O(7-x) (YBCO) nanobridges from c-axis oriented films. The novelty regards the use of a thin titanium mask used in the patterning process. The use of the Ti makes simpler the fabrication procedure guaranteeing high quality devices, as demonstrated by transport measurements. Critical temperatures and critical current densities scale with the width of the micro-bridge down to 200 nm in agreement with most results available in literature. The actual properties of the devices, performances, yield and reproducibility, along with an accurate control on doping, may allow the use of these micro-bridges for nanoscale experiments.

Transport properties of high quality Nb/semiconductor/Nb long Josephson junctions based on metamorphic In_0.75Ga_0.25As epitaxial layers are reported. Different junction geometries and fabrication procedures are presented that allow a systematic comparison with quasiclassical theory predictions. The impact of junction transparency is highlighted and a procedure capable of yielding a high junction quality factor is identified., Comment: 11 pages, 3 figures

We present various concepts and experimental procedures to produce biepitaxial ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}x}$ grain-boundary Josephson junctions. The device properties have an interesting phenomenology, related in part to the possible influence of $\mathrm{``}\ensuremath{\pi}$ loops.'' The performance of our junctions and superconducting quantum interference devices indicates significant improvement in the biepitaxial technique. Further, we propose methods for fabricating circuits in which 0 and $\ensuremath{\pi}$ loops are controllably located on the same chip.

The properties of YBa 2 Cu 3 O 7− x grain boundary Josephson junctions have been reproducibly modified by a focused electron beam irradiation. The original junctions were fabricated by using the biepitaxial technique on (110) SrTiO 3 substrates. The technique utilizes the property of YBa 2 Cu 3 O 7− x film to grow (103)-oriented on the bare substrate and (001)-oriented on the part of the substrate with the MgO seed layer, providing Josephson junctions of good quality and excellent reproducibility. The junction parameters can be adjusted controllably by applying an appropriate irradiation dose. Electron irradiation reduced the critical current of the junctions I C and increased the normal state specific resistivity. The disappearance of the excess current and the shift of the voltage position of the Fiske steps were also observed. Isothermal annealing partly restores the original junction properties. We also speculate that some aspects of the nature of the grain boundary barriers can be better understood from the study of the transport properties of irradiated junctions. PACS: 74.50+r, 74.72Bk, 74.76Bz, 85.25Cp

The properties of the Y 1 Ba 2 Cu 3 O 7-x biepitaxial Josephson junctions were reproducibly modified by a focused electron beam irradiation of the interface region. The original structures are based on 45° a-axis tilt grain boundaries. The junction parameters can be controllably adjusted by applying an appropriate irradiation dose. Electron irradiation reduced the critical current of the junctions and increased the normal state specific resistivity The disappearance of the excess current and the shift of the voltage position of the Fiske steps were also observed. Isothermal annealing partly restores the original junction properties. Some aspects of the nature of the grain boundary barriers can be better understood from the study of the properties of irradiated junctions.

We report the realization of a ballistic Josephson interferometer. The interferometer is made by a quantum ring etched in a nanofabricated two-dimensional electron gas confined in an InAs-based heterostructure laterally contacted to superconducting niobium leads. The Josephson current flowing through the structure shows oscillations with h/e flux periodicity when threading the loop with a perpendicular magnetic field. This periodicity, in sharp contrast with the h/2e one observed in conventional dc superconducting quantum interference devices, confirms the ballistic nature of the device in agreement with theoretical predictions. This system paves the way for the implementation of interferometric Josephson pi-junctions, and for the investigation of Majorana fermions., 4+ pages, 4 colored figures

We report on the study of the phase dynamics of high-critical-temperature superconductor Josephson junctions. We realized YBa${}_{2}$Cu${}_{3}$O${}_{7\ensuremath{-}x}$ grain boundary biepitaxial junctions in the submicron scale using low-loss substrates and analyzed their dissipation by comparing the transport measurements with Monte Carlo simulations. The behavior of the junctions can be fitted using a model based on two quality factors, which results in a frequency-dependent damping. Moreover, our devices can be designed to have Josephson energy of the order of the Coulomb energy. In this unusual energy range, phase delocalization strongly influences the device's dynamics, promoting the transition to a quantum phase diffusion regime. We study the signatures of such a transition by combining the outcomes of Monte Carlo simulations with the analysis of the device's parameters, the critical current, and the temperature behavior of the low-voltage resistance ${R}_{0}$.

We show that low-angle grain boundaries (GB) in high-temperature superconductors exhibit intermediate Abrikosov vortices with Josephson cores, whose length $l$ along GB is smaller that the London penetration depth, but larger than the coherence length. We found an exact solution for a periodic vortex structure moving along GB in a magnetic field $H$ and calculated the flux flow resistivity $R_F(H)$, and the nonlinear voltage-current characteristics. The predicted $R_F(H)$ dependence describes well our experimental data on $7^{\circ}$ unirradiated and irradiated $YBa_2Cu_3O_7$ bicrystals, from which the core size $l(T)$, and the intrinsic depairing density $J_b(T)$ on nanoscales of few GB dislocations were measured for the first time. The observed temperature dependence of $J_b(T)=J_{b0}(1-T/T_c)^2$ indicates a significant order parameter suppression in current channels between GB dislocation cores., 5 pages 5 figures. Phys. Rev. Lett. (accepted)

We present various concepts and experimental procedures to fabricate biepitaxial YBa 2Cu 3O 7-x grain boundary Josephson junctions. Different types of structures can be realized including "π-loops" in which one of the junctions is intrinsically π-phase shifted. Due to its versatility the biepitaxial technique offers the possibility to investigate basic aspects of the physics of grain boundary Josephson junctions, and also the influence of intrinsic and extrinsic d-wave induced effects in transport properties. Further, we discuss the possibility to produce circuits in which "0-" and "π-loops" are controllably located on the same chip, and intrinsic d-wave effects can be exploited.

The effects of the order parameter symmetry and the interface grain boundary orientation on the transport properties of YBa/sub 2/Cu/sub 3/O/sub 7-x/ biepitaxial grain boundary junctions have been investigated. 45/spl deg/ [100] tilt and twist junctions on SrTiO/sub 3/ [110] and MgO [110] substrates by employing respectively MgO and SrTiO/sub 3/ as seed layers have been fabricated. More complex junctions by using CeO as seed layers have also been fabricated and analyzed. The analysis of experimental data points towards a predominant d-wave symmetry of the superconductive order parameter.

The properties of single submicron high-temperature superconductor (HTS) rings are investigated. The Little-Parks effect is observed and is accompanied by an anomalous behavior of the magnetic dependence of the resistance, which we ascribe to non-uniform vorticity (superfluid angular momentum) within the ring arms. This effect is linked to the peculiar HTS-relationship between the values of the coherence length and the London penetration depth.

YBa(2)Cu(3)O(7-delta) (YBCO) grain boundaries characterized by a misalignment of the c-axes (45 degrees c-axis tilt or 45 degrees c-axis twist) have been obtained by employing a recently implemented biepitaxial technique. Junctions based on these grain boundaries exhibit good Josephson properties useful for applications. High values of the I(C)R(N) product and a Fraunhofer-like dependence of the critical current on the magnetic field, differently from traditional biepitaxial junctions, have been obtained. The correlation between transport properties and microstructure has been investigated by Transmission Electron Microscopy (TEM), which was also performed on previously measured junctions. The presence of atomically clean basal plane (BP) faced tilt boundaries, among other types of interfaces, has been shown. The possibility of selecting these kinds of boundaries by controlling film growth, and their possible advantages in terms of reproducibility and uniformity of the junction properties an discussed. The possibility of employing these junctions to explore the symmetry of the order parameter is also discussed. (C) 1999 Elsevier Science B.V. All rights reserved.

YBa2Cu3O7-x artificial grain boundary Josephson junctions have been fabricated, employing a recently implemented biepitaxial technique. The grain boundaries can be obtained by controlling the orientation of the MgO seed layer and are characterized by a misalignment of the c-axes (45 degrees a-axis tilt or 45 degrees a-axis twist). These types of grain boundaries are still mostly unexplored. We carried out a complete characterization of their transport properties and microstructure. Junctions and de SQUIDs associated with these grain boundaries exhibit an excellent Josephson phenomenology and high values of the ICRN product and of the magnetic flux-to-voltage transfer parameter respectively. Remarkable differences in the transport parameters of tilt and twist junctions have been observed, which can be of interest for several applications. A maximum speed of Josephson vortices as calculated from the voltage step values of the order of 2 x 10(6) m s(-1) is obtained. These devices could also have some impact on experiments designed to study the symmetry of the order parameter, exploiting their microstructure and anisotropic properties. High-resolution electron microscopy showed the presence of perfect basal plane faced boundaries in the cross sections of tilt boundaries.

We have fabricated and characterized Hall probes on an In0.75Al0.25As/In0.75Ga0.25As two-dimensional electron gas with lateral sizes down to 100 nm. We studied the dependence of the low temperature (4 K) magnetic field sensitivity on the probe size, showing that the best flux sensitivity is achieved by devices of ≈ 200 nm, employing highly doped systems ( n ∼ 1 0 12 cm−2). Hall bars with sizes down to the range of 200–250 nm show a magnetic field sensitivity of a few Gauss, corresponding to a flux sensitivity equal to ≈ 1 0 − 2 Φ 0 .

YBa/sub 2/Cu/sub 3/O/sub 7/-/sub x/ junctions and dc SQUIDs have been realized by employing 45/spl deg/ a-axis tilt grain boundaries through a fabrication procedure based on the biepitaxial technique. YBa/sub 2/Cu3O/sub 7-x/ grows mainly oriented [103] on SrTiO/sub 3/ and [001] on the MgO seed layer. A wide characterization of the tilt junctions and SQUID properties has been carried out. High values of the I/sub C/R/sub N/ quality factor and of the magnetic flux-to-voltage transfer parameter have been obtained, The observed phenomenology confirms differences from the one typical of 45/spl deg/ c-axis tilt grain boundary junctions and gives important information on the nature of the current steps appearing at finite voltages in the current-voltage characteristics. These devices could also have some impact on experiments designed to study the symmetry of the order parameter, exploiting their microstructure and anisotropic properties. A maximum speed of Josephson vortices as calculated from the voltage step values, of the order of 2 10/sup 6/ m/sec is obtained, which encourages high frequency applications.

The magnetic-field evolution of Coulomb blockade peaks in lateral In0.75Ga0.25As/In0.75Al0.25As quantum dots in the few-electron regime is reported. Quantum dots are defined by gates evaporated onto a 60-nm-thick hydrogen silsesquioxane insulating film. A gyromagnetic factor g∗≈4.4 is measured via zero-bias spin spectroscopy and a transition from singlet to triplet spin configuration is found at an in-plane magnetic field B=0.7 T. This observation opens the way to the manipulation of singlet and triplet states at moderate fields and its relevance for quantum information applications will be discussed.

We report on the study of the phase dynamics of high critical temperature superconductor Josephson junctions. We realized YBa$_2$Cu$_3$O$_{7-x}$ (YBCO) grain boundary (GB) biepitaxial junctions in the submicron scale, using low loss substrates, and analyzed their dissipation by comparing the transport measurements with Monte Carlo simulations. The behavior of the junctions can be fitted using a model based on two quality factors, which results in a frequency dependent damping. Moreover, our devices can be designed to have Josephson energy of the order of the Coulomb energy. In this unusual energy range, phase delocalization strongly influences the device's dynamics, promoting the transition to a quantum phase diffusion regime. We study the signatures of such a transition by combining the outcomes of Monte Carlo simulations with the analysis of the device's parameters, the critical current and the temperature behavior of the low voltage resistance $R_0$., Comment: 8 pages, 4 figures

The properties of single submicron high-temperature superconductor (HTS) rings are investigated. The Little-Parks effect is observed and is accompanied by an anomalous behavior of the magnetic dependence of the resistance, which we ascribe to non-uniform vorticity (superfluid angular momentum) within the ring arms. This effect is linked to the peculiar HTS-relationship between the values of the coherence length and the London penetration depth., 14 pages, 3 figures