Topological mechanics of gyroscopic metamaterials

By L. Nash, D. Kleckner, Alismari Read, V. Vitelli, Ari M. Turner, William T. M. Irvine. Proceedings of the National Academy of Sciences of the United States of America, 2015

748 citations recorded by the source corpus.

Significance We have built a new type of mechanical metamaterial: a “gyroscopic metamaterial” composed of rapidly spinning objects that are coupled to each other. At the edges of these materials, we find sound waves that are topologically protected (i.e. they cannot be scattered backward or into the bulk). These waves, which propagate in one direction only, are directly analogous to edge currents in quantum Hall systems. Through a mathematical model, we interpret the robustness of these edge waves in light of the subtle topological character of the bulk material. Crucially, these edge motions can be controlled by distorting the metamaterial lattice, opening new avenues for the control of sound in matter. Topological mechanical metamaterials are artificial structures whose unusual properties are protected very much like their electronic and optical counterparts. Here, we present an experimental and theoretical study of an active metamaterial—composed of coupled gyroscopes on a lattice—that breaks time-reversal symmetry. The vibrational spectrum displays a sonic gap populated by topologically protected edge modes that propagate in only one direction and are unaffected by disorder. We present a mathematical model that explains how the edge mode chirality can be switched via controlled distortions of the underlying lattice. This effect allows the direction of the edge current to be determined on demand. We demonstrate this functionality in experiment and envision applications of these edge modes to the design of one-way acoustic waveguides.

Subfields: Atomic and Molecular Physics, and Optics, Biomedical Engineering, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/f80783cfdb390be11d3b2b068d2720061b688c10

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

In Biomedical Engineering

In Electronic, Optical and Magnetic Materials

Citations in the corpus

Exceptional topology of non-Hermitian systems (2019, neutral): “…problems in atomic and particle physics, as well as in nuclear reactions (Majorana, 1931a, 1931b; Breit and Wigner, 1936; Feshbach, Porter, and Weisskopf, 1954; Feshbach, 1958; Fano, 1961), all the way to applications in biological systems (Nelson and Shnerb, 1998; Lubensky and Nelson, 2000).”
Tailoring Structure‐Borne Sound through Bandgap Engineering in Phononic Crystals and Metamaterials: A Comprehensive Review (2022, background): “For elastic waves, these analogs includes Landau Level [163], quantum Hall based structures with robust chiral edge states [164],”
Acoustic metamaterials: From local resonances to broad horizons (2016, background): “Realizations of the chiral edge modes in mechanical systems have also appeared in systems such as a two-dimensional array of coupled pendula ( 182 ) and an oscillator array consisting of spinning masses ( 183 ).”
Artificial gauge fields in materials and engineered systems (2017, neutral): “where t denotes time, xi(t) describes the displacement of the ith oscillator, i ∈ N and Dij are related to spring constants coupling different degrees of freedom [196,197].”
Fracton hydrodynamics (2020, background): “Since hydrodynamic equations are ultimately classical, it may also be possible to mimic these effects using engineered active matter [86].”