Observation of cyclotron resonance and measurement of the hole mass in optimally-doped La$_{2-x}$Sr$_{x}$CuO$_4$

TL;DR

This study uses terahertz spectroscopy in high magnetic fields to observe cyclotron resonance in a cuprate superconductor, measuring the hole effective mass and scattering rate, advancing understanding of charge dynamics in high-Tc materials.

Contribution

It reports the first direct measurement of hole cyclotron mass in La$_{2-x}$Sr$_{x}$CuO$_4$ using time-domain terahertz spectroscopy under pulsed magnetic fields.

Findings

Hole cyclotron mass measured as 4.9±0.8 m_e.

Scattering rate increases with magnetic field.

Consistent with cyclotron absorption of p-type carriers.

Abstract

Using time-domain terahertz spectroscopy in pulsed magnetic fields up to 31 T, we measure the terahertz optical conductivity in an optimally-doped thin film of the high temperature superconducting cuprate La$_{1.84}$Sr$_{0.16}$CuO$_4$. We observe systematic changes in the circularly-polarized complex optical conductivity that are consistent with cyclotron absorption of p-type charge carriers characterized by a cyclotron mass of $4.9\pm 0.8$ $m_{\rm e}$, and a scattering rate that increases with magnetic field. These results open the door to studies aimed at characterizing the degree to which electron-electron interactions influence carrier masses in cuprate superconductors.