Topological modes bound to dislocations in mechanical metamaterials

By J. Paulose, B. Chen, V. Vitelli. Nature Physics, 2014

338 citations recorded by the source corpus.

Mechanical metamaterials are artificial structures whose properties originate from their geometry. In such structures, it is now shown that topological modes can exist that are robust against a range of structural deformations. Mechanical metamaterials are artificial structures with unusual properties, such as negative Poisson ratio, bistability or tunable vibrational properties, that originate in the geometry of their unit cell1,2,3,4,5. Often at the heart of such unusual behaviour is a soft mode: a motion that does not significantly stretch or compress the links between constituent elements. When activated by motors or external fields, soft modes become the building blocks of robots and smart materials. Here, we demonstrate the existence of topological soft modes that can be positioned at desired locations in a metamaterial while being robust against a wide range of structural deformations or changes in material parameters6,7,8,9,10. These protected modes, localized at dislocations in deformed kagome and square lattices, are the mechanical analogue of topological states bound to defects in electronic systems11,12,13,14. We create physical realizations of the topological modes in prototypes of kagome lattices built out of rigid triangular plates. We show mathematically that they originate from the interplay between two Berry phases: the Burgers vector of the dislocation and the topological polarization of the lattice. Our work paves the way towards engineering topologically protected nanomechanical structures for molecular robotics or information storage and read-out.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/ce9ea7027f165e925eb5946e706bd2ce5691083e

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Citations in the corpus

Topological active matter (2020, background): “Topological defects and topologically protected modes (such as chiral edge states) are intertwined 21–24 .”
Mechanical metamaterials associated with stiffness, rigidity and compressibility: a brief review (2017, background): “Tailoring the porosity of structures [135] in topological designs can yield complex ordered patterns, thereby achieving selective buckling via states of self-stress [41,136].”
Mechanical metamaterials: a state of the art (2019, background): “auxetic materials) [12–20], negative compressibility transitions [21], unusual dynamic behaviour for wave propagation [22–24], enhanced mechanical properties (robust buckling responses against structural perturbations) [25, 26], improved strength-to-weight ratios [27–29]), programmable shape transfo”
Artificial gauge fields in materials and engineered systems (2017, positive): “Topological modes in isostatic lattices have been observed in deformed kagome lattices [201] and in a 1D mechanical system of rigid links and rotors [202], which resembles the topological Su–Schrieffer–Heeger (SSH) model [203], and might open new possibilities to study effects beyond electronic syst”
Active Particles in Complex and Crowded Environments (2016, background): “ive matter systems on lattices: Recently there has been growing interest in topological eects in both quantum (Hasan and Kane, 2010; Ran et al., 2009) and classical systems (Kane and Lubensky, 2014; Paulose et al., 2015), where the behavior at the edge of the system is dierent from that in the bulk.”
Quantization of fractional corner charge in Cn -symmetric higher-order topological crystalline insulators (2018, background): “[73] Jayson Paulose, Bryan Gin-ge Chen, and Vincenzo Vitelli, “Topological modes bound to dislocations in mechanical metamaterials,” Nature Physics 11, 153 EP – (2015).”