Ultrasonic wave generation in two-band organic conductors due to thermoelectric effect

2017 ◽  
Vol 31 (31) ◽  
pp. 1750250 ◽  
Author(s):  
Danica Krstovska

A linear thermoelectric generation of a longitudinal ultrasonic wave in organic conductors with two conducting channels, quasi-one dimensional (q1D) and quasi-two dimensional (q2D), is investigated theoretically. The magnetic field and temperature dependences of the amplitude of generated through Nernst effect wave in [Formula: see text]-(BEDT-TTF)2KHg(SCN)4 for two boundary conditions, isothermal and adiabatic are obtained. Findings show a preference of one type of a boundary over another in the wave generation and propagation depending on the magnetic field strength and temperature. At lower temperatures and above B[Formula: see text]=[Formula: see text]4 T, the wave amplitude for adiabatic boundary is smaller compared to the one for isothermal boundary although there is a heat flux through the conductor’s surface in the latter. Both the q1D and q2D charge carriers contribute to the observation of the effect but with different magnitude due to the different drift velocity along the direction of wave propagation.

Author(s):  
Enza Orlandi ◽  
Livio Triolo

We consider the one-dimensional, nonlocal, evolution equation derived by De Masi et al. (1995) for Ising systems with Glauber dynamics, Kac potentials and magnetic field. We prove the existence of travelling fronts, their uniqueness modulo translations among the monotone profiles and their linear stability for all the admissible values of the magnetic field for which the underlying spin system exhibits a stable and metastable phase.


2002 ◽  
Vol 65 (5) ◽  
Author(s):  
Kazuaki Iwasa ◽  
Masahumi Kohgi ◽  
Arsen Gukasov ◽  
Jean-Michel Mignot ◽  
Naokazu Shibata ◽  
...  

2016 ◽  
Vol 30 (03) ◽  
pp. 1550260 ◽  
Author(s):  
I. Grusha ◽  
M. Menteshashvili ◽  
G. I. Japaridze

We derive an effective spin Hamiltonian for the one-dimensional half-filled asymmetric ionic Hubbard model (IHM) with alternating on-site interaction in the limit of strong repulsion. It is shown that the effective Hamiltonian is that of a spin S = 1/2 anisotropic XXZ Heisenberg chain with alternating next-nearest-neighbor (NNN) and three-spin couplings in the presence of a uniform and a staggered magnetic field.


2016 ◽  
Vol 34 (4) ◽  
pp. 421-425
Author(s):  
Christian Nabert ◽  
Karl-Heinz Glassmeier

Abstract. Shock waves can strongly influence magnetic reconnection as seen by the slow shocks attached to the diffusion region in Petschek reconnection. We derive necessary conditions for such shocks in a nonuniform resistive magnetohydrodynamic plasma and discuss them with respect to the slow shocks in Petschek reconnection. Expressions for the spatial variation of the velocity and the magnetic field are derived by rearranging terms of the resistive magnetohydrodynamic equations without solving them. These expressions contain removable singularities if the flow velocity of the plasma equals a certain characteristic velocity depending on the other flow quantities. Such a singularity can be related to the strong spatial variations across a shock. In contrast to the analysis of Rankine–Hugoniot relations, the investigation of these singularities allows us to take the finite resistivity into account. Starting from considering perpendicular shocks in a simplified one-dimensional geometry to introduce the approach, shock conditions for a more general two-dimensional situation are derived. Then the latter relations are limited to an incompressible plasma to consider the subcritical slow shocks of Petschek reconnection. A gradient of the resistivity significantly modifies the characteristic velocity of wave propagation. The corresponding relations show that a gradient of the resistivity can lower the characteristic Alfvén velocity to an effective Alfvén velocity. This can strongly impact the conditions for shocks in a Petschek reconnection geometry.


1991 ◽  
Vol 05 (01n02) ◽  
pp. 3-30 ◽  
Author(s):  
J. Carmelo ◽  
P. Horsch ◽  
P.A. Bares ◽  
A.A. Ovchinnikov

The Landau-Luttinger liquid formulation is used to investigate the physics of the one-dimensional Hubbard model in a magnetic field of arbitrary strength H. The low lying charge and spin excitations are studied. A novel branch of sound wave-like spin excitations arises for H>0. The low temperature thermodynamics is considered in some detail.


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