Observations across many families of unconventional materials motivate the search for robust mechanisms producing linear in temperature dc resistivity. Berezinskii-Kosterlitz-Thouless quantum phase transitions are commonplace in holographic descriptions of finite density matter, separating critical and ordered phases. We show that at a holographic Berezinskii-Kosterlitz-Thouless critical point, if the unstable operator is coupled to the current via irrelevant operators, then a linear contribution to the resistivity is universally obtained. We also obtain broad power law tails in the optical conductivity that shift spectral weight from the Drude peak as well as interband energy scales. We give a partial realization of this scenario using an Einstein-Maxwell-pseudoscalar bulk theory. The instability is a vectorial mode at nonzero wave vector, which is communicated to the homogeneous current via irrelevant coupling to an ionic lattice.

• Received 24 September 2012

DOI:https://doi.org/10.1103/PhysRevD.86.124046