Quantum oscillations in the Luttinger model with quadratic band touching: applications to pyrochlore iridates

TL;DR

This paper develops a theory for quantum oscillations in the Luttinger model with quadratic band touching, explaining aperiodic Shubnikov de Haas signals in pyrochlore iridates like Pr2Ir2O7, and connecting experimental observations with unconventional Landau level structures.

Contribution

It introduces a theoretical framework for quantum oscillations in the Luttinger model with quadratic band touching, relevant for pyrochlore iridates, and explains observed aperiodic signals.

Findings

Aperiodic SdH signals are consistent with unconventional Landau level structures.

The Luttinger model with quadratic band touching accurately describes the magneto- and Hall resistivities.

The theory justifies the use of the Luttinger model for pyrochlore iridates.

Abstract

Motivated by recent experiments on Pr2Ir2O7, we provide a theory of quantum oscillations in the Luttinger model with quadratic band touching, modelled for the spin-orbit-coupled conduction electrons in pyrochlore iridates. The magneto- and Hall resistivities are computed for electron- and hole-doped systems, and the corresponding Shubnikov de Haas (SdH) signals are investigated. The SdH signals are characterized by aperiodic behaviors that originate from the unconventional Landau level structures of the Luttinger model near the neutrality point, such as the inter-Landau level crossing, nonuniform Landau level spacings and non-parabolic dispersions along the applied magnetic-field direction. The aperiodic SdH signals observed in the paramagnetic state of Pr2Ir2O7 are shown to be consistent with such behaviors, justifying the use of the Luttinger model and the quadratic band touching spectrum as excellent starting points for physics of pyrochlore iridates. The implications of these results are discussed in light of recent theoretical and experimental devel- opments in these systems.