Abstract.A study of dipolarization fronts of the Earth's magnetotail has been performed using seven years (2001)(2002)(2003)(2004)(2005)(2006)(2007) of Cluster data. Events both with and without highspeed earthward flows are included. A superposed epoch analysis of the data shows that the dipolarization is preceeded by a decrease of B z before the increase. The duration of the dipolarization tends to be decreasing with increasing velocity of the plasma flows. The thickness of the dipolarization front is on average 1.8 plasma inertial lengths, independent of the plasma velocity. We find that the events fall into two categories: Earthward and tailward moving dipolarizations. The dipolarization fronts can be assumed to be tangential discontinuities and the currents on the front have mainly a perpendicular component.

The magnetosheath flow may take the form of large amplitude, yet spatially localized, transient increases in dynamic pressure, known as "magnetosheath jets" or "plasmoids" among other denominations. Here, we describe the present state of knowledge with respect to such jets, which are a very common phenomenon downstream of the quasi-parallel bow shock. We discuss their properties as determined by satellite observations (based on both case and statistical studies), their occurrence, their relation to solar wind and foreshock conditions, and their interaction with and impact on the magnetosphere. As carriers of plasma and corresponding momentum, energy, and magnetic flux, jets bear some similarities to bursty bulk flows, which they are compared to. Based on our knowledge of jets in the near Earth environment, we discuss the expectations for jets occurring in other planetary and

Understanding the interplay between many-body phenomena and non-equilibrium in systems with entangled spin and orbital degrees of freedom is a central objective in nano-electronics. We demonstrate that the combination of Coulomb interaction, spin-orbit coupling and valley mixing results in a particular selection of the inelastic virtual processes contributing to the Kondo resonance in carbon nanotubes at low temperatures. This effect is dictated by conjugation properties of the underlying carbon nanotube spectrum at zero and finite magnetic field. Our measurements on a clean carbon nanotube are complemented by calculations based on a new approach to the nonequilibrium Kondo problem which well reproduces the rich experimental observations in Kondo transport.

Abstract. The observational rate of mirror mode waves in Venus's magnetosheath for solar maximum conditions is studied and compared with previous results for solar minimum conditions. It is found that the number of mirror mode events is approximately 14 % higher for solar maximum than for solar minimum. A possible cause is the increase in solar UV radiation, ionizing more neutrals from Venus's exosphere and the outward displacement of the bow shock during solar maximum. Also, the solar wind properties (speed, density) differ for solar minimum and maximum. The maximum observational rate, however, over Venus's magnetosheath remains almost the same, with only differences in the distribution along the flow line. This may be caused by the interplay of a decreasing solar wind density and a slightly higher solar wind velocity for this solar maximum. The distribution of strengths of the mirror mode waves is shown to be exponentially falling off, with (almost) the same coefficient for solar maximum and minimum. The plasma conditions in Venus's magnetosheath are different for solar minimum as compared to solar maximum. For solar minimum, mirror mode waves are created directly behind where the bow shock will decay, whereas for solar maximum all created mirror modes can grow.

We present multipoint observations of earthward moving dipolarization fronts and energetic particle injections from NASA's Magnetospheric Multiscale mission with a focus on electron acceleration. From a case study during a substorm on 02 August 2015, we find that electrons are only accelerated over a finite energy range, from a lower energy threshold at ~7–9 keV up to an upper energy cutoff in the hundreds of keV range. At energies lower than the threshold energy, electron fluxes decrease, potentially due to precipitation by strong parallel electrostatic wavefields or initial sources in the lobes. Electrons at energies higher than the threshold are accelerated cumulatively by a series of impulsive magnetic dipolarization events. This case demonstrates how the upper energy cutoff increases, in this case from ~130 keV to >500 keV, with each dipolarization/injection during sustained activity. We also present a simple model accounting for these energy limits that reveals that electron energization is dominated by betatron acceleration.

A suspended, doubly clamped single-wall carbon nanotube is characterized at cryogenic temperatures. We observe specific switching effects in dc-current spectroscopy of the embedded quantum dot. These have been identified previously as nano-electromechanical self-excitation of the system, where positive feedback from single-electron tunneling drives mechanical motion. A magnetic field suppresses this effect, by providing an additional damping mechanism. This is modeled by eddy current damping, and confirmed by measuring the resonance quality factor of the radio-frequency-driven nano-electromechanical resonator in an increasing magnetic field.

A magnetic field, through its vector potential, usually causes measurable changes in the electron wave function only in the direction transverse to the field. Here we demonstrate experimentally and theoretically that in carbon nanotube quantum dots, combining cylindrical topology and bipartite hexagonal lattice, a magnetic field along the nanotube axis impacts also the longitudinal profile of the electronic states. With the high (up to 17 T) magnetic fields in our experiment the wave functions can be tuned all the way from "half-wave resonator" shape, with nodes at both ends, to "quarter-wave resonator" shape, with an antinode at one end. This in turn causes a distinct dependence of the conductance on the magnetic field. Our results demonstrate a new strategy for the control of wave functions using magnetic fields in quantum systems with nontrivial lattice and topology.As first noticed by Aharonov and Bohm [1], when a charged quantum particle travels in a finite electromagnetic potential, its wave function acquires a phase whose magnitude depends on the travelled path. For particles with electric charge q moving along a closed path, the phase shift ϕ AB = qΦ B /h, known as Aharonov-Bohm shift, is expressed in terms of the magnetic flux Φ B across the enclosed area. Because Φ B depends only on the magnitude of the magnetic field component normal to this area's surface, the phase is acquired along directions transverse to the magnetic field, see Fig. 1(a). In mesoscopic rings or tubular structures pierced by a magnetic field, the phase changes the quantization condition for the tangential part of the electronic wave vector by k ⊥ → k ⊥ + ϕ AB /r (with r the radius of the ring or tubulus) and is at the basis of remarkable quantum interference phenomena [2]. However, as the perpendicular components of the magnetic vector potential commute with the parallel component of the momentum, a parallel magnetic field is not expected to affect the wave function along the field.Also in carbon nanotubes (CNTs), the electronic wave function acquires an Aharonov-Bohm phase when a magnetic field is applied along the nanotube axis [3], see Fig. 1(a). The phase gives rise to resistance oscillations in a varying magnetic flux [4]. Since it changes k ⊥ , it also changes the energy E(k) of an electronic state, through its dependence on the wave vector k = (k , k ⊥ (B )). Such a magnetic field dependence of the energies has been observed through beatings in Fabry-Perot patterns [5], or in the characteristic evolution of excitation spectra of CNT quantum dots in the sequential tunneling [6-9] and Kondo [10-15] regimes.In this Letter we show that the combination of the bipartite honeycomb lattice, the cylindrical topology of the nanotubes, and the confinement in the quantum dot intertwines the usually separable parallel and transverse components of the wave function. This leads to unusual tunability of the wave function in the direction parallel to the magnetic field. Experimentally, it manifests in a pronounced variation of the conductanc...

We study the ion density and temperature in the predipolarization and postdipolarization plasma sheets in the Earth's magnetotail using 9 years (2001–2009) of Cluster data. For our study we selected cases when Cluster observed dipolarization fronts (DFs) with an earthward plasma flow greater than 150km/s. We perform a statistical study of the temperature and density variations during the DF crossings. Earlier studies concluded that on average, the temperature increases while the density decreases across the DF. Our statistical results show a more diverse picture: While ∼54% of the DFs follow this pattern (category A), for ∼28% the temperature decreases while the density increases across the DF (category B). We found an overall decrease in thermal pressure for category A DFs with a more pronounced decrease at the DF duskside, while DFs of category B showed no clear pattern in the pressure change. Both categories are associated with earthward plasma flows but with some difference: (1) category A flows are faster than category B flows, (2) the observations indicate that category B flows are directed perpendicular to the current in the near-Earth current sheet while category A flows are tilted slightly duskward from this direction, and (3) the background Bz of category B is higher than that of category A. Based on these results, we hypothesize that after reconnection takes place, a bursty bulk flow emerges with category A characteristics, and as it travels earthward, it further evolves into category B characteristics, which is in a more dipolarized region with slower plasma flow (closer to the flow-braking region).