Sondheimer magneto-oscillations as a probe of Fermi surface reconstruction in underdoped cuprates

TL;DR

This paper introduces Sondheimer oscillations as a new, robust method to probe Fermi surface reconstruction in underdoped cuprates, especially at high temperatures where traditional quantum oscillations fail.

Contribution

It proposes and analyzes Sondheimer oscillations as an alternative to quantum oscillations for studying Fermi surfaces in cuprates, highlighting their advantages and potential to distinguish different Fermi surface scenarios.

Findings

Sondheimer oscillations depend on FS parameters and are observable at moderate fields and high temperatures.

The spectrum reveals universal features that differentiate FS reconstruction scenarios.

The study characterizes how FS geometry and doping affect the oscillation spectrum.

Abstract

Determining the Fermi surface (FS) volume in underdoped cuprates is crucial for understanding the nature of the strongly correlated pseudogap phase. Conventional quantum oscillation techniques, typically used for this purpose, are inapplicable in this high-temperature regime due to thermal and disorder-induced smearing of Landau levels. We propose Sondheimer oscillations (SO), semiclassical oscillations of in-plane magnetoresistivity in thin films, as a robust alternative probe of FS reconstruction. SO arise from the commensuration between the cyclotron radius and film thickness, do not rely on Landau quantization, and remain observable at moderate fields and elevated temperatures where quantum oscillations are suppressed. Their frequencies depend solely on the FS parameters (e.g., curvature), and not on specific details of scattering mechanisms. SO are also sensitive to the coherence of inter-layer tunneling, allow contributions from individual FS pockets to be distinguished in the frequency domain, and naturally include the Yamaji angle effect (if present in the system) as a prominent feature in the frequency spectrum. We compute SO spectra as a function of the magnetic field orientation for three representative scenarios: (i) an unreconstructed large FS, (ii) a spin density wave reconstructed FS with volume $p/4$, and (iii) a fractionalized Fermi liquid (FL$^*$) with pocket volume $p/8$ (here $p$ is the hole doping). We show that the SO spectrum offers a wealth of universal features that could be used to differentiate between these scenarios. In particular, we highlight a FS geometry-dependent phase shift between oscillations in longitudinal and transverse conductivities, characterize how the FS curvature can be extracted from SO if the film orientation is perpendicular to the crystallographic $c$-axis, and analyze the evolution of the SO spectrum with doping.