Magic angle effects of the one-dimensional axis conductivity in quasi-one dimensional conductors

TL;DR

This paper introduces a new semiclassical theory explaining the magic angle effects in one-dimensional conductivity of quasi-one-dimensional conductors, emphasizing the role of momentum-dependent Fermi velocity near spin density wave instabilities.

Contribution

It presents a novel explanation for the magic angle effect in one-dimensional conductivity, accounting for Fermi velocity dependence without relying on Fermi surface corrugation or hot spots.

Findings

Explains magic angle effects via Fermi velocity momentum dependence.

Does not require Fermi surface corrugation or hot spots.

Applicable to systems near spin density wave instability.

Abstract

In quasi-one-dimensional conductors, the conductivity in both one-dimensional axis and interchain direction shows peaks when magnetic field is tilted at the magic angles in the plane perpendicular to the conducting chain. Although there are several theoretical studies to explain the magic angle effect, no satisfactory explanation, especially for the one-dimensional conductivity, has been obtained. We present a new theory of the magic angle effect in the one-dimensional conductivity by taking account of the momentum-dependence of the Fermi velocity, which should be large in the systems close to a spin density wave instability. The magic angle effect is explained in the semiclassical equations of motion, but neither the large corrugation of the Fermi surface due to long-range hoppings nor hot spots, where the relaxation time is small, on the Fermi surface are required.