Abstract
Capturing the dynamic electronic band structure of a correlated material presents a powerful capability for uncovering the complex couplings between the electronic and structural degrees of freedom. When combined with ultrafast laser excitation, new phases of matter can result, since far-from-equilibrium excited states are instantaneously populated. Here, we elucidate a general relation between ultrafast non-equilibrium electron dynamics and the size of the characteristic energy gap in a correlated electron material. We show that carrier multiplication via impact ionization can be one of the most important processes in a gapped material, and that the speed of carrier multiplication critically depends on the size of the energy gap. In the case of the charge-density wave material 1T-TiSe2, our data indicate that carrier multiplication and gap dynamics mutually amplify each other, which explains—on a microscopic level—the extremely fast response of this material to ultrafast optical excitation.
Highlights
The MIT Faculty has made this article openly available
In the case of 1T-TiSe2, we argue that this gap-size dependent non-equilibrium behaviour explains—on a microscopic level—the extremely fast response of this charge-density wave (CDW) material to an optical excitation
We note that the quenching of the CDW in 1T-TiSe2 evolves on similar timescales as the carrier multiplication process, that is, the CDW gap size is dynamically reduced[15,16]
Summary
The MIT Faculty has made this article openly available. Please share how this access benefits you. If there are universal relations between the non-equilibrium electron relaxation dynamics and the size of the characteristic energy gaps in a correlated material.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
