arXiv subjects

W. -S. Zeng

Publications and source records attributed to W. -S. Zeng.

2 recordsLinked to original sources

arXiv1996

Displacive Excitation of Coherent Phonons in YBa_2Cu_3 O_7: An Optical Evidence for the Van-Hove Singularity

The amplitude of displacive excitation of coherent phonons ({\it DECP}) in $YBa_2Cu_3O_7$ observed in time-resolved spectroscopy increases by a very large factor of 15 between 20 K (below $T_c$) and 100 K (above $T_c$). Microscopic modelling of phonon excitation reveals that these amplitude changes of the {\it $A_{1g}$} mode phonons are related to the existence of the {\it Van-Hove} singularity (VHS) below but very close to Fermi energy. PACS numbers: 78.47.+p, 74.25.Gz, 74.25.Jb, 71.15.Fv

cond-mat↗

arXiv1996

The Structure of Barium in the hcp Phase Under High Pressure

Recent experimental results on two hcp phases of barium under high pressure show interesting variation of the lattice parameters. They are here interpreted in terms of electronic structure calculation by using the LMTO method and generalized pseudopotential theory (GPT) with a NFE-TBB approach. In phase II the dramatic drop in c/a is an instability analogous to that in the group II metals but with the transfer of s to d electrons playing a crucial role in Ba. Meanwhile in phase V, the instability decrease a lot due to the core repulsion at very high pressure. PACS numbers: 62.50+p, 61.66Bi, 71.15.Ap, 71.15Hx, 71.15La

cond-mat↗