Magnetic incommensurability and fluctuating charge density waves in the repulsive Hubbard model

Magnetic and charge susceptibilities of the two-dimensional repulsive Hubbard model are investigated applying a strong coupling diagram technique in which the expansion in powers of the hopping constants is used. For small lattices and high temperatures results are in agreement with Monte Carlo simulations. With the departure from half-filling $x$ the low-frequency magnetic susceptibility becomes incommensurate and the incommensurability parameter grows with $x$. The incommensurability, its dependence on frequency and on $x$ resemble experimental results in lanthanum cuprates. Also for finite $x$ sharp maxima appear in the static charge susceptibility. The maxima are finite which points to the absence of the long-range charge ordering (static stripes). However, for $x\approx 0.12$ the maxima are located near the momenta $(0,\pm\pi/2)$, $(\pm\pi/2,0)$. In this case an interaction of carriers with tetragonal distortions can stabilize stripes with the wavelength of four lattice spacings, as observed in the low-temperature tetragonal phase of cuprates. As follows from the obtained results, the magnetic incommensurability is not a consequence of the stripes.Comment: 4 pages, 3 figures, manuscript for proceefings of LT2

MHD boundary layers with non-equilibrium ionization and finite rates Quarterly report, 1 Jun. - 1 Sep. 1969

Ionization and recombination rates in boundary layer of magnetohydrodynamic channel electrod

Spin current injection by intersubband transitions in quantum wells

We show that a pure spin current can be injected in quantum wells by the absorption of linearly polarized infrared radiation, leading to transitions between subbands. The magnitude and the direction of the spin current depend on the Dresselhaus and Rashba spin-orbit coupling constants and light frequency and, therefore, can be manipulated by changing the light frequency and/or applying an external bias across the quantum well. The injected spin current should be observable either as a voltage generated via the anomalous spin-Hall effect, or by spatially resolved pump-probe optical spectroscopy.Comment: minor changes, short version publishe

Progress of Land Classification in the National Forests

The growth of the National Forests in the public land states of the west was largely a spasmodic mushroom growth. The first Forests were created under the authority of the Act of 1891, which provided merely for reservation without administration. A sudden increase in these areas, through Presidential proclamation, was at first set aside by Congress but resulted in the passage of the Act of June 4, 1897, which provided for the administration and protection of the areas reserved. The great body of timber land under Government ownership today was withdrawn during the ten years following the passage of that Act, the National Forest area, inclusive of Alaska, reaching its maximum April 20, 1910, with a total of 167,710,956 acres, gross

Ferdinand Augustus Silcox, Forester and Humanitarian

Fifth in the regular succession of Chiefs of the Forest Service, United States Department of Agriculture, Ferdinand Augustus Silcox was the third Chief to gain his forestry experience and win his administrative spurs in the great practical school of the National Forests of the West