Savings, expectations and technological unemployment: a generalization of assumptions for the Hicksian fixwage traverse

This paper examines the role of alternative assumptions on savings and expectations for the fixwage traverse with strong forward biased technological change. After briefly outlining the model, some peculiarities of the adjustment path under the Hicksian Q-Assumption are investigated. Subsequently, the consequences of several savings functions consistent with the assumption of static expectations are explored. With all but one of these assumptions the possibility of permanent technological unemployment emerges. Additionally, the assumption of adaptive expectations is introduced, in which case technological unemployment throughout the early phase prevails. Furthermore, oscillating growth rates emerge, indicating the possibility of technologically caused business cycles. --Traverse analysis,technological unemployment,Neo-Austrian theory

Synthesis, phase stability, structural and physical properties of 11-type iron chalcogenides

This article reviews recent experimental investigations on two binary Fe-chalcogenides: FeSe and Fe$_{1+y}$Te. The main focus is on synthesis, single crystal growth, chemical composition, as well as on the effect of excess iron on structural, magnetic, and transport properties of these materials. The structurally simplest Fe-based superconductor Fe$_{1+x}$Se with a critical temperature $T_c \approx$ 8.5 K undergoes a tetragonal to orthorhombic phase transition at a temperature $T_s \approx$ 87 K. No long-range magnetic order is observed down to the lowest measured temperature in Fe$_{1+x}$Se. On the other hand, isostructural Fe$_{1+y}$Te displays a complex interplay of magnetic and structural phase transitions in dependence on the tuning parameter such as excess amount of Fe or pressure, but it becomes a superconductor only when Te is substituted by a sufficient amount of Se. We summarize experimental evidence for different competing interactions and discuss related open questions.Comment: 14 pages, 12 figures, Feature Article, Part of Special Issue on Iron-Based High Temperature Superconductor

Protective capping of topological surface states of intrinsically insulating Bi2_2Te3_3

We have identified epitaxially grown elemental Te as a capping material that is suited to protect the topological surface states of intrinsically insulating Bi$_2$Te$_3$. By using angle-resolved photoemission, we were able to show that the Te overlayer leaves the dispersive bands of the surface states intact and that it does not alter the chemical potential of the Bi$_2$Te$_3$ thin film. From in-situ four-point contact measurements, we observed that the conductivity of the capped film is still mainly determined by the metallic surface states and that the contribution of the capping layer is minor. Moreover, the Te overlayer can be annealed away in vacuum to produce a clean Bi$_2$Te$_3$ surface in its pristine state even after the exposure of the capped film to air. Our findings will facilitate well-defined and reliable ex-situ experiments on the properties of Bi$_2$Te$_3$ surface states with nontrivial topology.Comment: 5 pages, 5 figures, 2 pages supplemental material accepted for publication in AIP Advance

Savings, Expectations and Technological Unemployment : A Generalization of Assumptions for the Hicksian Fixwage Traverse

This paper examines the role of alternative assumptions on savings and expectations for the fixwage traverse with strong forward biased technological change. After briefly outlining the model, some peculiarities of the adjustment path under the Hicksian Q-Assumption are investigated. Subsequently, the consequences of several savings functions consistent with the assumption of static expectations are explored. With all but one of these assumptions the possibility of permanent technological unemployment emerges. Additionally, the assumption of adaptive expectations is introduced, in which case technological unemployment throughout the early phase prevails. Furthermore, oscillating growth rates emerge, indicating the possibility of technologically caused business cycles

Low-temperature phase diagram of Fe1+yTe

We used low-temperature synchrotron x-ray diffraction to investigate the structural phase transitions of Fe1+yTe in the vicinity of a tricitical point in the phase diagram. Detailed analysis of the powder diffraction patterns and temperature dependence of the peak-widths in Fe1+yTe showed that two-step structural and magnetic phase transitions occur within the compositional range 0.11 $\leq y \leq$ 0.13. The phase transitions are sluggish indicating a strong competition between the orthorhombic and the monoclinic phases. We combine high-resolution diffraction experiments with specific heat, resistivity, and magnetization measurements and present a revised temperature-composition phase diagram for Fe1+yTe.Comment: 10 pages, 14 figure

Flexibilität zahlt sich aus

In den Kosten- und Nutzenerwägungen von Unternehmen bezüglich möglicher Mobilitätsformen für Dienstwege findet Car-Sharing in der Regel keine Beachtung, weil die Mobilitätsoption von Unternehmen nicht wahrgenommen wird oder unbekannt ist. Dabei bietet Car-Sharing eine Reihe von Vorteilen und hilft, Ineffizienzen zu vermeiden

Emergence of an incipient ordering mode in FeSe

The structurally simplest Fe-based superconductor FeSe with a critical temperature $T_{c}\approx$ 8.5 K displays a breaking of the four-fold rotational symmetry at a temperature $T_{s}\approx 87$ K. We investigated the electronic properties of FeSe using scanning tunneling microscopy/spectroscopy (STM/S), magnetization, and electrical transport measurements. The results indicated two new energy scales (i) $T^{*} \approx$ 75 K denoted by an onset of electron-hole asymmetry in STS, enhanced spin fluctuations, and increased positive magnetoresistance; (ii) $T^{**} \approx$ 22 - 30 K, marked by opening up of a partial gap of about 8 meV in STS and a recovery of Kohler's rule. Our results reveal onset of an incipient ordering mode at $T^{*}$ and its nucleation below $T^{**}$. The ordering mode observed here, both in spin as well as charge channels, suggests a coupling between the spins with charge, orbital or pocket degrees of freedom.Comment: 5 pages, 4 figure

Impurity-induced bound states inside the superconducting gap of FeSe

We investigate the local density of states in the vicinity of a native dumbbell defect arising from an Fe vacancy in FeSe single crystals. The tunneling spectra close to the impurity display two bound states inside the superconducting gap, equally spaced with respect to zero energy but asymmetric in amplitude. Using spin-polarized density functional theory (DFT) calculations on realistic slab models with Fe vacancy, we show that such a defect does not induce a local magnetic moment. Therefore, the dumbbell defect is considered as non-magnetic. Thus, the in-gap bound states emerging from a non-magnetic defect-induced pair-breaking suggest a sign changing pairing state in this material.Comment: 8 pages, 6 figure