paper

Spectroscopic fingerprints of gapless type-II fracton phases

arXiv:2106.15631 · doi:10.1103/PhysRevB.105.L180416

Abstract

Fracton phases feature elementary excitations with fractionalized mobility and are exciting interest from multiple areas of theoretical physics. However, the most exotic 'type-II' fracton phases, like the Haah codes, currently have no known experimental diagnostics. Here, we explain how type-II fracton phases with gapless gauge modes, such as the Haah code, may be identified experimentally. Our analysis makes use of the 'multipole gauge theory' description of type-II fracton phases, which exhibits ultraviolet-infrared (UV-IR) mixing. We show that neutron scattering experiments on gapless type-II fracton phases should generically exhibit exotic pinch points in the structure factor, with distinctive anisotropic contours as a direct consequence of UV-IR mixing. This characteristic pinch point structure provides a clean diagnostic of type-II fracton phases. We also identify distinctive signatures of the (3+1)-D Haah code in the low-temperature specific heat.

5+7 pages, 3+5 figures; v2 includes discussion of a classical spin model with parabolic pinch points; title change in v3

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