MODULATION OF A SEMICONDUCTOR-TO-SEMIMETAL TRANSITION AT 7-THZ VIA COHERENT LATTICE-VIBRATIONS

This letter introduces the general notion of significantly modulating the physical characteristics of a solid on a terahertz time scale with coherent lattice vibrations. We show, as an example, experiments in w hich coherent phonons are optically excited in single-crystal Ti2O3, w hich is a narrow-gap semiconductor at 300 K and gradually transforms i nto a semimetal at 600 K. Quantitative comparison of previous equilibr ium measurements to our new transient measurements suggests that the i nduced coherent lattice vibration is significantly modulating the semi conductor-to-semimetal transition at 7 THz.