Shubnikov-de Haas oscillations in YBa_2Cu_4O_8

TL;DR

This study reports the observation of Shubnikov-de Haas oscillations in underdoped YBa2Cu4O8, revealing small Fermi surface pockets and quasiparticle effective mass, indicating a common feature in underdoped cuprates.

Contribution

First observation of Shubnikov-de Haas oscillations in YBa2Cu4O8, demonstrating small Fermi surface pockets in this compound, expanding understanding of electronic structure in underdoped cuprates.

Findings

Oscillation frequency of 660 T indicating small Fermi pockets

Effective quasiparticle mass of 2.7 times the electron mass

Small Fermi surface pockets are a generic feature in underdoped cuprates

Abstract

We report the observation of Shubnikov-de Haas oscillations in the underdoped cuprate superconductor YBa$_2$Cu$_4$O$_8$ (Y124). For field aligned along the c-axis, the frequency of the oscillations is $660\pm 30$ T, which corresponds to $\sim 2.4$ % of the total area of the first Brillouin zone. The effective mass of the quasiparticles on this orbit is measured to be $2.7\pm0.3$ times the free electron mass. Both the frequency and mass are comparable to those recently observed for ortho-II YBa$_2$Cu$_3$O$_{6.5}$ (Y123-II). We show that although small Fermi surface pockets may be expected from band structure calculations in Y123-II, no such pockets are predicted for Y124. Our results therefore imply that these small pockets are a generic feature of the copper oxide plane in underdoped cuprates.