Rectifying acoustic phonons

Magnons and acoustic phonons in Y3ÀxBixFe5O12

We use Brillouin light scattering ~BLS! to study a series of single-crystal Bi-doped yttrium iron garnet Y32xBixFe5O12 ~Bi-YIG! prepared with x5 0, 0.14, 0.36, 0.54, and 0.92. BLS shows that the optimal laser power should be as low as possible, <5 mW. BLS manifests the Bi-concentration dependence of the magnetic and mechanic properties of Bi-YIG. Two bulk magnons are observed. One is the therma...

Coupled-mode stop bands of acoustic phonons in semiconductor superlattices.

Transverse acoustic phonons in germanium near the melting point

2014 The transverse acoustic phonon dispersion in germanium has been studied along [111] and [100] up to 935 °C, only 2 degrees below the melting point Tm. No evidence of softening is found, neither near the Brillouin Zone boundary, nor uniformly throughout the BZ. The phonon energies decrease slowly and linearly with increasing T from 100 K to Tm. This suggests that the free electron density a...

Coherent acoustic phonons in nanostructures investigated by asynchronous optical sampling

A new optical pump-probe technique is implemented for the investigation of acoustic phonon dynamics in the GHz to THz frequency range which is based on two asynchronously linked femtosecond lasers. Asynchronous optical sampling (ASOPS) provides the performance of on all-optical oscilloscope and allows us to record optically induced lattice dynamics over nanosecond times with 200 femtoseconds re...

Coherent Acoustic Phonons in a Semiconductor Quantum Dot

Coherent acoustic phonons in PbS quantum dots are observed using femtosecond optical techniques. This is the first observation of coherent acoustic phonons in a semiconductor quantum dot; the phonons are generated through the deformation-potential coupling to the quantum-dot exciton. The acoustic modes are weakly damped, and we also find extremely weak coupling (S , 0.01) to the optical modes. ...