Non-Fermi-liquid magic angle effects in high magnetic fields

We investigate a theoretical problem of electron-electron interactions in an inclined magnetic field in a quasi-one-dimensional (Q1D) conductor. We show that they result in strong non-Fermi-liquid corrections to a specific heat, provided that the direction of the magnetic field is far from the so-called Lebed's magic angles (LMAs). If magnetic field is directed close to one of the LMAs, the specific heat corrections become small and the Fermi-liquid picture restores. As a result, we predict Fermi-liquid–non-Fermi-liquid angular crossovers in the vicinities of the LMA directions of the field. We suggest to perform the corresponding experiment in the Q1D conductor ${\left(\mathrm{Per}\right)}_2\mathrm{Au}{\left(\mathrm{mnt}\right)}_2$ under pressure in magnetic fields of the order of $H\simeq 25\text{T}$.

Figure 1

One of the Feynman's diagrams, corresponding to the lowest-order corrections to electron free energy from electron-electron interactions. Solid lines with arrows stand for electron Green's functions, whereas solid lines without arrows represent electron-electron interactions. All electrons have the same spin projection on a magnetic field.

Figure 2

Normalized correction to electron specific heat, $-\mathrm{\Delta }C/\left(g^2{C}_0\right)$, due to the Feynman's diagrams of Fig. 1, is numerically calculated by means of Eqs. (22) and (23). The main minimum of the correction, corresponding to the LMA with $\alpha ={45}^{\circ }$, is split into two secondary dips.