arXiv subjects

Hua Wu

Publications and source records attributed to Hua Wu.

256 records · Page 15Linked to original sources

arXiv2001

Spin state and phase competition in TbBaCo_{2}O_{5.5} and the lanthanide series LnBaCo_{2}O_{5+δ} (0<=δ<=1)

A clear physics picture of TbBaCo$_{2}$O$_{5.5}$ is revealed on the basis of density functional theory calculations. An antiferromagnetic (AFM) superexchange coupling between the almost high-spin Co$^{3+}$ ions competes with a ferromagnetic (FM) interaction mediated by both p-d exchange and double exchange, being responsible for the observed AFM-FM transition. And the metal-insulator transition is accompanied by an xy/xz orbital-ordering transition. Moreover, this picture can be generalized to the whole lanthanide series, and it is predicted that a few room-temperature magnetoresistance materials could be found in LnBa$_{1-x}$A$_{x}$Co$_{2}$O$_{5+δ}$ (Ln=Ho,Er,Tm,Yb,Lu; A=Sr,Ca,Mg).

cond-mat.mtrl-sci↗

arXiv1994

Ballistic transport: A view from the quantum theory of motion

Ballistic transport of electrons through a quantum wire with a constriction is studied in terms of Bohm's interpretation of quantum mechanics, in which the concept of a particle orbit is permitted. The classical bouncing ball trajectories, which justify the name ``ballistic transport'', are established in the large wave number limit. The formation and the vital role of quantum vortices is investigated.

cond-mat↗

arXiv1994

Numerical investigation of iso-spectral cavities built from triangles

We present computational approaches as alternatives to the recent microwave cavity experiment by S. Sridhar and A. Kudrolli (Phys. Rev. Lett. {\bf 72}, 2175 (1994)) on iso-spectral cavities built from triangles. A straightforward proof of iso-spectrality is given based on the mode matching method. Our results show that the experiment is accurate to 0.3% for the first 25 states. The level statistics resemble those of GOE when the integrable part of the spectrum is removed.

solv-int↗

arXiv1994

``Chaos" in Nuclear High Spin Spectroscopy

The Projected Shell Model with zero-, two- and four-quasiparticle configurations is used to investigate the level statistics, i.e. chaoticity, of high spin spectroscopy. The model can describe many high spin phenomena and with the present configuration space has sufficient number of levels for statistical analysis. It is found that the degree of chaoticity has a sensitive dependence on the classification of levels in question, and that it steadily increases with excitation energy and angular momentum.

nucl-th↗