scholarly journals Quantum Dots in Strong Magnetic Fields: Stability Criteria for the Maximum Density Droplet

1993 ◽  
Vol 46 (3) ◽  
pp. 345 ◽  
Author(s):  
AH MacDonald ◽  
SR Eric Yang ◽  
MD Johnson

In this article we discuss the ground state of a parabolically confined quantum dot in the limit of very strong magnetic fields where the electron system is completely spin-polarised and all electrons are in the lowest Landau level. Without electron-electron interactions the ground state is a single Slater determinant corresponding to a droplet centred on the minimum of the confinement potential and occupying the minimum area allowed by the Pauli exclusion principle. Electron-electron interactions favour droplets of larger area. We derive exact criteria for the stability of the maximum density droplet against edge excitations and against the introduction of holes in the interior of the droplet. The possibility of obtaining exact results in the strong magnetic field case is related to important simplifications associated with broken time-reversal symmetry in a strong magnetic field.

1988 ◽  
Vol 03 (04) ◽  
pp. 345-351 ◽  
Author(s):  
M. MOSHINSKY ◽  
G. LOYOLA

We consider the nucleons in the triplet state of the deuteron bound by an oscillator potential and in a strong magnetic field. Using an appropriate linear canonical transformation, we solve the problem exactly. The expectation value of the distance between the nucleons in the plane perpendicular to the magnetic field diminishes slowly as we increase the latter, which suggests that the triplet state of the deuteron is stable. The conclusion is not altered when we consider possible transitions from the triplet to the singlet state due to the action of the magnetic field on the spins.


There are only two methods of producing a strong magnetic field. The first is by a solenoid, and the second by a solenoid with an iron core in it. The iron is introduced for the purpose of diminishing the magnetic resistance of the magnetic flux, and makes possible the production of much stronger fields than can be obtained without it. This is the principle on which modern electro-magnets are constructed, and by means of them it is possible to obtain field up to 60 kilogauss in a volume of a few cubic millimetres. The saturation of iron, however, makes it impossible to go further than this. According to the present theory of ferro-magnetism we can hardly hope to obtain any ferro-magnetic material which will give a much higher saturation-value than the iron used in modern electro-magnets; and without such a material it is impossible to increase the field obtainable by this means.


1996 ◽  
Vol 10 (23) ◽  
pp. 1141-1149 ◽  
Author(s):  
CHOON-LIN HO ◽  
V.R. KHALILOV ◽  
CHI YANG

We obtain the equations that define the equilibrium of a homogeneous relativistic gas of neutrons, protons and electrons in a constant magnetic field as applied to the conditions that probably occur near the center of neutron stars. We compute the relative densities of the particles at equilibrium and the Fermi momentum of electrons in the strong magnetic field as function of the density of neutrons and the magnetic field induction. Novel features are revealed as to the ratio of the number of protons to the number of neutrons at equilibrium in the presence of large magnetic fields.


When an α -particle moves in a magnetic field it describes a curved trajectory, the curvature of which is closely related to its charge and velocity. Thus the track of an α -particle obtained in a Wilson expansion chamber, placed in a magnetic field, will be no longer straight, but curved. From study of these curved tracks it should be possible to obtain information about the loss of energy and the change of the charge of a single atom moving through matter. The difficulty of this experiment is the necessity of using a strong magnetic field. The author has recently published a description of a method of producing strong magnetic fields for a small fraction of a second. The strength of these fields is of the order required for this kind of experiment, and the short period of time (0•01 sec.) during which the field is available is still very long compared with the time taken by the α -particle to describe its trajectory (1.0•10 -7 sec.). A preliminary account of this experiment has already been published, but it took about a year to complete the experimental results. In the present paper the description is given of the experimental arrangements used and of the results obtained.


2009 ◽  
Vol 23 (07) ◽  
pp. 891-902
Author(s):  
E. V. GORBAR ◽  
V. P. GUSYNIN ◽  
V. A. MIRANSKY

We analyze the gap equation for Dirac quasiparticles in graphene in a magnetic field using a low-energy effective model with a contact interaction. It is found that the order parameters connected with the quantum Hall (QH) ferromagnetism and the magnetic catalysis scenarios necessarily coexist. The ground-state solutions of the gap equation describe all the recently discovered novel QH plateaus in graphene in strong magnetic fields.


Author(s):  
Fei-Lu Wang ◽  
Xiao-Xing Pei ◽  
Bo Han ◽  
Hui-Gang Wei ◽  
Da-Wei Yuan ◽  
...  

In this paper, the recent studies of laboratory astrophysics with strong magnetic fields in China have been reviewed. On the Shenguang-II laser facility of the National Laboratory on High-Power Lasers and Physics, a laser-driven strong magnetic field up to 200 T has been achieved. The experiment was performed to model the interaction of solar wind with dayside magnetosphere. Also the low beta plasma magnetic reconnection (MR) has been studied. Theoretically, the model has been developed to deal with the atomic structures and processes in strong magnetic field. Also the study of shock wave generation in the magnetized counter-streaming plasmas is introduced.


2017 ◽  
Vol 20 (3) ◽  
pp. 128-135
Author(s):  
A.A. Kudreyko ◽  
R.N. Migranova ◽  
A.R. Khafizov

The role of anchoring effects in thin nematic films confined between two parallel plates was theoretically examined. The bulk and surface free energy densities weree xpanded up to O(e2) and the perturbated contributions were calculated. It is shown that the minimum of the free energy corresponds to the solution of the Euler-Lagrange equations and satisfies the Ericksen inequalities. The identified bifurcation points can estimate the influence of the saddle-splay constant k24 towards periodic perturbations of a director in the presence of strong magnetic field.


2005 ◽  
Vol 70 (8) ◽  
pp. 1133-1156 ◽  
Author(s):  
Alexander V. Turbiner ◽  
Alexei B. Kaidalov ◽  
Juan Carlos López Vieyra

Easy physics-inspired approximations of the total and binding energies for the H atom and for the molecular ions H2(+)(ppe), H3(2+)(pppe), (HeH)++(αpe), He2(3+)(ααe) as well as quadrupole moment for the H atom and the equilibrium distances of the molecular ions in strong magnetic fields > 109 G are proposed. The idea of approximation is based on the assumption that the dynamics of the one-electron Coulomb system in a strong magnetic field is governed by the ratio of transverse to longitudinal sizes of the electronic cloud.


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