Strong-Field Bloch Electron Interferometry for Band Structure Retrieval

TL;DR

This paper introduces a novel strong-field interferometry technique using Landau-Zener transitions in Bloch electrons to directly measure band structures, demonstrated by determining graphene's Fermi velocity with high precision.

Contribution

The work presents a new method, strong-field Bloch electron interferometry, for retrieving band structure information with femtosecond resolution in solid materials.

Findings

Measured graphene's Fermi velocity as (1.07±0.04) nm/fs near K points.

Demonstrated the feasibility of band structure retrieval using strong-field interferometry.

Applicable to various materials for real-time band structure analysis.

Abstract

When Bloch electrons in a solid are exposed to a strong optical field, they are coherently driven in their respective bands where they acquire a quantum phase as the imprint of the band shape. If an electron approaches an avoided crossing formed by two bands, it may be split by undergoing a Landau-Zener transition. We here employ subsequent Landau-Zener transitions to realize strong-field Bloch electron interferometry (SFBEI), allowing us to reveal band structure information. In particular, we measure the Fermi velocity (band slope) of graphene in the vicinity of the K points as (1.07$\pm$0.04) nm fs$^{-1}$. We expect SFBEI for band structure retrieval to apply to a wide range of material systems and experimental conditions, making it suitable for studying transient changes in band structure with femtosecond temporal resolution at ambient conditions.