Graphene nanoribbons (GNRs) are a fascinating class of quasi-one-dimensional semiconductors consisting of nanometer-wide strips of hexagonally bonded carbon atoms [1]. Recent progress in fabrication techniques have enabled the realization of atomically precise GNRs with diverse edge geometries, widths, and complex nanoarchitectures [2]. In this talk, I will present graphene nanoribbons as a promising platform for controlling and manipulating unconventional electronic phases, drawing from both ab initio and model Hamiltonian calculations. First, I will explore the emergence of topological phases in armchair-edged nanoribbons induced by lattice deformations [3]. Second, I will demonstrate the formation of half-semimetallic phases in zigzag-edged nanoribbons upon incorporation into a lateral heterostructure [4, 5]. Third, I will discuss the development of ultra-flat bands and π-electron magnetism in chevron-edged graphene nanoribbons under an external electric field [6]. These findings may open new possibilities for engineering quantum phases in one-dimensional crystals, with potential applications in spintronics and related device concepts.

[1] O. V. Yazyev, Account of Chemical Research 46, 2319 (2013).
[2] A. Narita, K. Müllen, Advanced Materials 32, 2001893 (2020).
[3] N. V. Tepliakov, J, Lischner, E. Kaxiras, A. A. Mostofi, M. Pizzochero, Physical Review Letters 130, 026401 (2023).
[4] N. V. Tepliakov, R. Ma, J. Lischner, E. Kaxiras, A. A. Mostofi, M. Pizzochero, Nano Letters 23, 6698 (2024).
[5] M. Pizzochero, N. V. Tepliakov, J. Lischner, A. A. Mostofi, E. Kaxiras, Nano Letters 24, 6521 (2024).
[6] R. Ma, N. V. Tepliakov, A. A. Mostofi, M. Pizzochero, in preparation