Direct observation of Floquet-Bloch states in monolayer graphene

Fuente: arXiv
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Main Authors: Choi, Dongsung, Mogi, Masataka, De Giovannini, Umberto, Azoury, Doron, Lv, Baiqing, Su, Yifan, Hübener, Hannes, Rubio, Angel, Gedik, Nuh
Format: Preprint
Published: 2024
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author Choi, Dongsung
Mogi, Masataka
De Giovannini, Umberto
Azoury, Doron
Lv, Baiqing
Su, Yifan
Hübener, Hannes
Rubio, Angel
Gedik, Nuh
author_facet Choi, Dongsung
Mogi, Masataka
De Giovannini, Umberto
Azoury, Doron
Lv, Baiqing
Su, Yifan
Hübener, Hannes
Rubio, Angel
Gedik, Nuh
contents Floquet engineering is a novel method of manipulating quantum phases of matter via periodic driving [1, 2]. It has successfully been utilized in different platforms ranging from photonic systems [3] to optical lattice of ultracold atoms [4, 5]. In solids, light can be used as the periodic drive via coherent light-matter interaction. This leads to hybridization of Bloch electrons with photons resulting in replica bands known as Floquet-Bloch states. After the direct observation of Floquet-Bloch states in a topological insulator [6], their manifestations have been seen in a number of other experiments [7-14]. By engineering the electronic band structure using Floquet-Bloch states, various exotic phase transitions have been predicted [15-22] to occur. To realize these phases, it is necessary to better understand the nature of Floquet-Bloch states in different materials. However, direct energy and momentum resolved observation of these states is still limited to only few material systems [6, 10, 14, 23, 24]. Here, we report direct observation of Floquet-Bloch states in monolayer epitaxial graphene which was the first proposed material platform [15] for Floquet engineering. By using time- and angle-resolved photoemission spectroscopy (trARPES) with mid-infrared (mid-IR) pump excitation, we detected replicas of the Dirac cone. Pump polarization dependence of these replica bands unequivocally shows that they originate from the scattering between Floquet-Bloch states and photon-dressed free-electron-like photoemission final states, called Volkov states. Beyond graphene, our method can potentially be used to directly observe Floquet-Bloch states in other systems paving the way for Floquet engineering in a wide range of quantum materials.
format Preprint
id arxiv_https___arxiv_org_abs_2404_14392
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Direct observation of Floquet-Bloch states in monolayer graphene
Choi, Dongsung
Mogi, Masataka
De Giovannini, Umberto
Azoury, Doron
Lv, Baiqing
Su, Yifan
Hübener, Hannes
Rubio, Angel
Gedik, Nuh
Mesoscale and Nanoscale Physics
Other Condensed Matter
Floquet engineering is a novel method of manipulating quantum phases of matter via periodic driving [1, 2]. It has successfully been utilized in different platforms ranging from photonic systems [3] to optical lattice of ultracold atoms [4, 5]. In solids, light can be used as the periodic drive via coherent light-matter interaction. This leads to hybridization of Bloch electrons with photons resulting in replica bands known as Floquet-Bloch states. After the direct observation of Floquet-Bloch states in a topological insulator [6], their manifestations have been seen in a number of other experiments [7-14]. By engineering the electronic band structure using Floquet-Bloch states, various exotic phase transitions have been predicted [15-22] to occur. To realize these phases, it is necessary to better understand the nature of Floquet-Bloch states in different materials. However, direct energy and momentum resolved observation of these states is still limited to only few material systems [6, 10, 14, 23, 24]. Here, we report direct observation of Floquet-Bloch states in monolayer epitaxial graphene which was the first proposed material platform [15] for Floquet engineering. By using time- and angle-resolved photoemission spectroscopy (trARPES) with mid-infrared (mid-IR) pump excitation, we detected replicas of the Dirac cone. Pump polarization dependence of these replica bands unequivocally shows that they originate from the scattering between Floquet-Bloch states and photon-dressed free-electron-like photoemission final states, called Volkov states. Beyond graphene, our method can potentially be used to directly observe Floquet-Bloch states in other systems paving the way for Floquet engineering in a wide range of quantum materials.
title Direct observation of Floquet-Bloch states in monolayer graphene
topic Mesoscale and Nanoscale Physics
Other Condensed Matter
url https://arxiv.org/abs/2404.14392