Pseudo-magnetic field-induced ultra-slow carrier dynamics in periodically strained graphene

TL;DR

This study demonstrates that pseudo-magnetic fields in periodically strained graphene can drastically slow down hot carrier relaxation, revealing new physical phenomena and potential applications in optoelectronics.

Contribution

It provides the first direct evidence that pseudo-magnetic fields induce ultra-slow carrier dynamics in strained graphene using time-resolved spectroscopy.

Findings

Pseudo-magnetic fields of ~100 T significantly slow carrier relaxation.

Strain-engineered graphene exhibits altered optical properties.

Ultra-slow carrier dynamics open new physics and device opportunities.

Abstract

The creation of pseudo-magnetic fields in strained graphene has emerged as a promising route to allow observing intriguing physical phenomena that would be unattainable with laboratory superconducting magnets. Scanning tunneling spectroscopy experiments have successfully measured the pseudo-Landau levels and proved the existence of pseudo-magnetic fields in various strained graphene systems. These giant pseudo-magnetic fields observed in highly deformed graphene can substantially alter the optical properties of graphene beyond a level that can be feasible with an external magnetic field, but the experimental signatures of the influence of such pseudo-magnetic fields have yet to be unveiled. Here, using time-resolved infrared pump-probe spectroscopy, we provide unambiguous evidence for ultra-slow carrier dynamics enabled by pseudo-magnetic fields in periodically strained graphene. Strong pseudo-magnetic fields of ~100 T created by non-uniform strain in graphene nanopillars are found to significantly decelerate the relaxation processes of hot carriers by more than an order of magnitude. Our finding presents unforeseen opportunities for harnessing the new physics of graphene enabled by pseudo-magnetic fields for optoelectronics and condensed matter physics.