Dynamic Magnetoelectric Effect in Ferromagnet-Superconductor Tunnel Junctions

We study the magnetization dynamics in a ferromagnet-insulator-superconductor tunnel junction and the associated buildup of the electrical polarization. We show that for an open circuit, the induced voltage varies strongly and nonmonotonically with the precessional frequency, and can be enhanced significantly by the superconducting correlations. For frequencies much smaller or much larger than the superconducting gap, the voltage drops to zero, while when these two energy scales are comparable, the voltage is peaked at a value determined by the driving frequency. We comment on the potential utilization of the effect for the low-temperature spatially-resolved spectroscopy of magnetic dynamics.Comment: 4.2 pages, 4 figure

Acoustic phonons and strain in core/shell nanowires

We study theoretically the low-energy phonons and the static strain in cylindrical core/shell nanowires (NWs). Assuming pseudomorphic growth, isotropic media, and a force-free wire surface, we derive algebraic expressions for the dispersion relations, the displacement fields, and the stress and strain components from linear elasticity theory. Our results apply to NWs with arbitrary radii and arbitrary elastic constants for both core and shell. The expressions for the static strain are consistent with experiments, simulations, and previous analytical investigations; those for phonons are consistent with known results for homogeneous NWs. Among other things, we show that the dispersion relations of the torsional, longitudinal, and flexural modes change differently with the relative shell thickness, and we identify new terms in the corresponding strain tensors that are absent for uncapped NWs. We illustrate our results via the example of Ge/Si core/shell NWs and demonstrate that shell-induced strain has large effects on the hole spectrum of these systems.Comment: 21 pages, 5 figure

SANCTION – VIRTUES AND LIMITATIONS IN EDUCATION

Reward and sanction are reactions of a person or an instance to a behavior that supports, respectively affects norms, values and people that are part of a constituted group (the collective of a classroom that is supervised by a teacher or the school community). If reward is always accompanied by positive affective states which value people and place them in a positive light, sanction, which has the role of correcting by showing that the way things are in the present is wrong becomes a “two blade knife”: it can do good (fix things by showing the right way they need to be done) or wrong (by humiliating the person who is sanctioned, by punishing), depending on how it is designed and used. Our purpose in the present article is to present several considerations on the rather non-educational way in which sanction is used in Romanian schools.sanction, educational sanction, non-educational sanction

Resonantly Tunable Majorana Polariton in a Microwave Cavity

We study the spectrum of a one-dimensional Kitaev chain placed in a microwave cavity. In the off-resonant regime, the frequency shift of the cavity can be used to identify the topological phase transition of the coupled system. In the resonant regime, the topology of the system can be controlled via the microwave cavity occupation and, moreover, for a large number of photons (classical limit), the physics becomes similar to that of periodically-driven systems (Floquet insulators). We also analyze numerically a finite chain and show the existence of a degenerate subspace in the presence of the cavity that can be interpreted as a \textit{Majorana polariton}.Comment: 11 pages, 6 figure

The transformation of industrial relations in Romania at the micro level

Subsequent to the collapse of the communist regime in 1989, Romania has undergone political and economic changes which have determined radical changes in industrial relations (IR). Nevertheless, ten years after the fall of the communist regime, the old and new elements still exist side by side, although labour legislation and an institutional framework similar to those in developed countries has been adopted. It appears that communist legacies, such as the specific economic and political context which exists in Romania, the lack of experience of all the actors involved in IR and also the current international context have all had an important impact on the emerging IR system in Romania. Nevertheless, there has been very little empirical research into how the IR system works in practice and how terms and conditions of employment are established and implemented at company level. The aim of this paper is, firstly, to present a new perspective on Crouch’s exchange theory of IR (1993) and, secondly, to use this approach to analyse empirical findings regarding the changes which have occurred in IR at the company level in Romania since 1989. The empirical findings will be presented for each of the six categories investigated, analysing the development of IR since 1989. After that, a synthesis of the findings will be presented in an attempt to answer the research questions indicated in the next section

Overview of industrial relations in Romania

Industrial relations (IR) have been rather extensively investigated in many eastern European countries in the last 15 years, but there is still very limited information about Romania. This article presents an overview of the main IR institutions, concerning both the legal framework as well as their operation in practice, in Romania. It examines the role of the state, employers associations, trade unions and collective bargaining from a historical perspective. In the final part, the changes that have occurred after 1989 in these selected parameters are discussed in the broader eastern European context. The study is based on primary data collected in 2000 and 2001 which aimed to identify what has changed since 1989 regarding the IR actors (i.e. state, employers associations and trade unions) and the relations between them. Seven officials from national institutions were interviewed: a government representative involved in the establishing of the Labour Code; two officials from employers associations; two trade union officials; the secretary of the Economic and Social Council; and the representative in Romania of the International Labour Organisation (ILO). An ILO official responsible for the activities of employers associations throughout central and eastern European countries was also interviewed. In addition, 25 (one-to-one) interviews were conducted in a total of fifteen companies which were studied during the research. Thirteen interviewees were managers or employers (three employers, three top managers, three human resource managers and four line managers), while twelve were employees (four shop stewards, seven employees and an unemployed person). Hence, data triangulation is used to ensure the reliability of the empirical evidenc

Circuit QED with Hole-Spin Qubits in Ge/Si Nanowire Quantum Dots

We propose a setup for universal and electrically controlled quantum information processing with hole spins in Ge/Si core/shell nanowire quantum dots (NW QDs). Single-qubit gates can be driven through electric-dipole-induced spin resonance, with spin-flip times shorter than 100 ps. Long-distance qubit-qubit coupling can be mediated by the cavity electric field of a superconducting transmission line resonator, where we show that operation times below 20 ns seem feasible for the entangling square-root-of-iSWAP gate. The absence of Dresselhaus spin-orbit interaction (SOI) and the presence of an unusually strong Rashba-type SOI enable precise control over the transverse qubit coupling via an externally applied, perpendicular electric field. The latter serves as an on-off switch for quantum gates and also provides control over the g factor, so single- and two-qubit gates can be operated independently. Remarkably, we find that idle qubits are insensitive to charge noise and phonons, and we discuss strategies for enhancing noise-limited gate fidelities.Comment: 6 pages main article + 12 pages supplement, 4 figure