Surface levels of organic conductors in a tilted in-plane magnetic field

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Danica Krstovska ◽  
Aleksandar Skeparovski

Abstract Surface quantum states in quasi-two dimensional organic conductors induced by an external magnetic field tilted in the plane of the layers are obtained and analyzed. In tilted magnetic fields, these states arise from the transitions of the electrons between the closed orbits on the sides of the Fermi surface determined by the electron momentum along the magnetic field direction p B and the coordinate of the center of electron revolution Z. By far, in organic conductors, the surface states have not been studied for tilted magnetic fields. In this work, we have performed detail analyses of the surface states in a tilted in-plane magnetic field by calculating the surface energy spectrum and surface wave functions in order to address their properties and features. We find that, in a tilted magnetic field, the surface levels have higher energies compared to those at zero tilt angle but can be observed only up to a certain tilt angle. The resonant magnetic field and angular values at which the peaks in the surface oscillations should be observed are obtained. Further theoretical and new experimental studies of the surface states in a tilted magnetic field might give new insights into the surface properties of quasi-two dimensional organic conductors. Additionally, they may reveal new information about the parameters of the Fermi surface of organic conductors necessary for its reconstruction.

2015 ◽  
Vol 15 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Matthias Ratajczak ◽  
Thomas Wondrak ◽  
Klaus Timmel ◽  
Frank Stefani ◽  
Sven Eckert

AbstractIn continuous casting DC magnetic fields perpendicular to the wide faces of the mold are used to control the flow in the mold. Especially in this case, even a rough knowledge of the flow structure in the mold would be highly desirable. The contactless inductive flow tomography (CIFT) allows to reconstruct the dominating two-dimensional flow structure in a slab casting mold by applying one external magnetic field and by measuring the flow-induced magnetic fields outside the mold. For a physical model of a mold with a cross section of 140 mm×35 mm we present preliminary measurements of the flow field in the mold in the presence of a magnetic brake. In addition, we show first reconstructions of the flow field in a mold with the cross section of 400 mm×100 mm demonstrating the upward scalability of CIFT.


1990 ◽  
Vol 140 ◽  
pp. 379-380
Author(s):  
Kazunari Shibata ◽  
Ryoji Matsumoto

Magnetohydrodynamic (MHD) mechanisms producing radio lobes, shells, and filaments in the Galactic center as well as in the gas disk of the Galaxy are studied by using two-dimensional MHD code: (a) the explosion in a magnetized disk, (b) the interaction of a rotating disk with vertical fields, and (c) the nonlinear Parker instability in toroidal magnetic fields in a disk. In all cases, dense shells or filaments are created along magnetic field lines in a transient state, in contrast to the quasi-equilibrium filaments perpendicular to magnetic fields.


1997 ◽  
Vol 163 ◽  
pp. 799-800
Author(s):  
Craig H. Smith ◽  
Christopher M. Wright ◽  
David K. Aitken ◽  
Patrick F. Roche

AbstractWe present the results from mid-infrared spectro-polarimetric observations of a number of bi-polar outflow sources. The specto-polarimetric data provides information on the polarization mechanism and the magnetic field direction. The field direction in the disks of the observed sources is most often normal to the ambient field direction and lies in the plane of the disk, indicating a toroidal rather than poloidal field configuration.


2014 ◽  
Vol 32 (10) ◽  
pp. 1247-1261 ◽  
Author(s):  
L. Turc ◽  
D. Fontaine ◽  
P. Savoini ◽  
E. K. J. Kilpua

Abstract. Magnetic clouds (MCs) are large-scale magnetic flux ropes ejected from the Sun into the interplanetary space. They play a central role in solar–terrestrial relations as they can efficiently drive magnetic activity in the near-Earth environment. Their impact on the Earth's magnetosphere is often attributed to the presence of southward magnetic fields inside the MC, as observed in the upstream solar wind. However, when they arrive in the vicinity of the Earth, MCs first encounter the bow shock, which is expected to modify their properties, including their magnetic field strength and direction. If these changes are significant, they can in turn affect the interaction of the MC with the magnetosphere. In this paper, we use data from the Cluster and Geotail spacecraft inside the magnetosheath and from the Advanced Composition Explorer (ACE) upstream of the Earth's environment to investigate the impact of the bow shock's crossing on the magnetic structure of MCs. Through four example MCs, we show that the evolution of the MC's structure from the solar wind to the magnetosheath differs largely from one event to another. The smooth rotation of the MC can either be preserved inside the magnetosheath, be modified, i.e. the magnetic field still rotates slowly but at different angles, or even disappear. The alteration of the magnetic field orientation across the bow shock can vary with time during the MC's passage and with the location inside the magnetosheath. We examine the conditions encountered at the bow shock from direct observations, when Cluster or Geotail cross it, or indirectly by applying a magnetosheath model. We obtain a good agreement between the observed and modelled magnetic field direction and shock configuration, which varies from quasi-perpendicular to quasi-parallel in our study. We find that the variations in the angle between the magnetic fields in the solar wind and in the magnetosheath are anti-correlated with the variations in the shock obliquity. When the shock is in a quasi-parallel regime, the magnetic field direction varies significantly from the solar wind to the magnetosheath. In such cases, the magnetic field reaching the magnetopause cannot be approximated by the upstream magnetic field. Therefore, it is important to take into account the conditions at the bow shock when estimating the impact of an MC with the Earth's environment because these conditions are crucial in determining the magnetosheath magnetic field, which then interacts with the magnetosphere.


2020 ◽  
Vol 34 (32) ◽  
pp. 2030007
Author(s):  
Andrei G. Lebed

It was theoretically predicted more than 20 years ago [A. G. Lebed and K. Yamaji, Phys. Rev. Lett. 80, 2697 (1998)], that a triplet quasi-two-dimensional (Q2D) superconductor could restore its superconducting state in parallel magnetic fields, which are higher than its upper critical magnetic field, [Formula: see text]. It is very likely that, recently, such phenomenon has been experimentally discovered in the Q2D superconductor UTe2 by Nicholas Butch, Sheng Ran, and their colleagues and has been confirmed by Japanese–French team. We review our previous theoretical results using such a general method that it describes the reentrant superconductivity in the abovementioned compound and will hopefully describes the similar phenomena, which can be discovered in other Q2D superconductors.


Nano Letters ◽  
2017 ◽  
Vol 17 (5) ◽  
pp. 2921-2927 ◽  
Author(s):  
Chao Wang ◽  
Haifeng Du ◽  
Xuebing Zhao ◽  
Chiming Jin ◽  
Mingliang Tian ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document