In 1962, Overhauser showed that within Hartree-Fock (HF) the electron gas is unstable to a spin-density wave state. Determining the true HF ground state has remained a challenge. Using numerical calculations for finite systems and analytic techniques, we study the unrestricted HF ground state of the three-dimensional electron gas. At high density, we find broken spin symmetry states with a near...

Momentum and spin represent fundamental dynamic properties of quantum particles and fields. In particular, propagating optical waves (photons) carry momentum and longitudinal spin determined by the wave vector and circular polarization, respectively. Here we show that exactly the opposite can be the case for evanescent optical waves. A single evanescent wave possesses a spin component, which is...

from the early 1950s, estimating the autocorrelations of polynomials with coefficients on the unit circle has found applications in ising spin systems and in surface acoustic wave designs. in this paper, a technique is introduced that not only estimates the autocorrelations, but for some special types of such polynomials, it locates the frequencies at which maximum autocorrelation occurs.

pμ dx /h̄, as is often quoted in the literature. We work in isotropic coordinates where the wave equations have a simple managable form and do not make a weak gravitational field approximation. We interpret these wave equations in terms of a quantum mechanical particle moving in medium with a spatially varying effective index of refraction. Due to the first order spatial derivative structure of ...

A graded Holstein-Primakoff realization of the SU(2/1) algebra is proposed. A spin-wave theory with a condition that the sublattice magnetization is zero is discussed. It is shown that the generalized spin-wave theory is appropriate to investigate the long-range spiral (incommensurate) phase of the t − J model at T = 0. The spin-spin correlator is calculated.

Based on the effective four-band model we analyze the spin response in the normal and superconducting state of the novel Fe-pnictide superconductors. While the normal state spin excitations are dominated by the continuum of the interorbital antiferromagnetic fluctuations and the intraband spin density wave fluctuations, the unconventional superconductivity yields different feedback. The resonan...

Pushing the frontiers of condensed-matter magnetism requires the development of tools that provide real-space, few-nanometre-scale probing of correlated-electron magnetic excitations under ambient conditions. Here we present a practical approach to meet this challenge, using magnetometry based on single nitrogen-vacancy centres in diamond. We focus on spin-wave excitations in a ferromagnetic mi...

Knowledge of the spin-wave dispersion relation is a prerequisite for explanation many magnonic phenomena as well practical design devices. Spin-wave measurement by established optical techniques such Brillouin light scattering or magneto-optical Kerr effect at ultralow temperatures often forbiddingly complicated. By contrast, microwave spectroscopy can be used all but it usually lacks spatial a...