[1] From time series of dissolved oxygen (O 2 ), phosphate (PO 4 ) and water temperature (T) during the last forty years in the Japan Sea Deep Water and the North Pacific Intermediate Water, we found that O 2 , PO 4 and T show a clear bidecadal oscillations of about 18 years superimposed on the linear trends of decrease of 0.47 mmol-O 2 kg À1 yr À1 and increase of 0.003 mmol-PO 4 kg À1 yr À1 and 0.005°C yr À1 in both two oceanic areas. The changes of O 2 , PO 4 and T in the two oceanic areas were synchronized despite the water formation systems of each area being independent. Both the linear trends and the oscillations of O 2 , PO 4 and T in the two oceanic areas also showed a strong correlation with the anomaly of the sea surface level pressure in the North Pacific that possibly affects the change of surface oceanic condition.
Using the von Neumann lattice formalism, we study compressible anisotropic states around the half-filled Landau levels in the quantum Hall system. In these states the unidirectional charge density wave (UCDW) state seems to be the most plausible state. The charge density profile and Hartree-Fock energy of the UCDW are calculated self-consistently. The wave length dependence of the energy for the UCDW is also obtained numerically. We show that the UCDW is regarded as a collection of the one-dimensional lattice Fermi-gas systems which extend to the uniform direction. The kinetic energy of the gas system is generated dynamically from the Coulomb interaction.
We study the compressible states in the quantum Hall system using a mean field theory on the von Neumann lattice. In the lowest Landau level, a kinetic energy is generated dynamically from Coulomb interaction. The compressibility of the state is calculated as a function of the filling factor ν and the width d of the spacer between the charge carrier layer and dopants. The compressibility becomes negative below a critical value of d and the state becomes unstable at ν = 1/2. Within a finite range around ν = 1/2, the stable compressible state exists above the critical value of d.PACS numbers: 73.40. Hm, 73.20.Dx The fractional quantum Hall effect (FQHE) [1] is observed in a two-dimensional electron system in a strong magnetic field around the rational filling factor ν with an odd denominator. The formation of the incompressible liquid state [2] successfully explains the FQHE. Recent experiments of the quantum Hall system around the rational filling factor ν with an even denominator (ex. 1/2) indicated the formation of the Fermi surface [3][4][5][6]. The composite fermion theory [7,8] can reasonably explain these experiments. However, the existence of the stable compressible Fermi liquid at ν = 1/2 is assumed a priori in this theory. It is more desirable to start from a microscopic theory and study the stability of the Fermi liquid state in the lowest Landau level space. Along this line a microscopic theory of the composite fermion has developed [9,10] and an effort is made to obtain the finite compressibility at ν = 1/2 [11]. Until now, understanding of the Fermi liquid property of the quantum Hall system in the microscopic level is unsatisfactory. The purpose of the present work is to study the stability of the compressible liquid state around ν = 1/2 using a mean field theory in the von Neumann lattice formalism [12]. We show that the stable Fermi-liquid-like state is formed if a distance between the 2d electron layer and dopants is larger than a critical value. We call this state the quantum Hall gas (QHG) state.In a strong magnetic field the free energy is quenched and kinetic energy, pressure, and compressibility are generated from the Coulomb interaction. Hence the pressure and compressibility of the QHG become negative in the jelium model where the uniform positive charge distribution cancels the Coulomb energy between electrons [13]. In realistic high-mobility samples, however, the positive charges (dopants) are separated from the negative charges (carriers) by the spacer in order to obtain highmobility and this separation d gives a positive contribution to the energy of the system. Owing to this contribution, the pressure and compressibility can become positive for a large d and the QHG state becomes stable. The critical values d c1 and d c2 for the pressure and compressibility are obtained in the present paper.In the lowest Landau level space, the total Hamiltonian for a two-dimensional system of this situation is given by,Here ρ(r) = ψ † (r)ψ(r) and the electron field operator ψ(r) is expanded by the...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.