Magnetic field-tuned quantum criticality in optimally electron-doped cuprate thin films

TL;DR

This study reveals a magnetic field-induced antiferromagnetic quantum phase transition in electron-doped cuprate thin films, highlighting the interplay between magnetic and superconducting states and providing insights into quantum criticality.

Contribution

It demonstrates a magnetic field-tuned quantum critical point in electron-doped cuprates, linking magnetic transitions to superconductivity suppression and ferromagnetic polarization.

Findings

AF quantum phase transition near 60 T observed

Hall number jumps from -x to 1-x at transition

Suppression of AF state predicts ferromagnetic polarization

Abstract

Antiferromagnetic (AF) spin fluctuations are commonly believed to play a key role in electron pairing of cuprate superconductors. In electron-doped cuprates, it is still in paradox about the interplay among different electronic states in quantum perturbations, especially between superconducting and magnetic states. Here, we report a systematic transport study on cation-optimized La2-xCexCuO4 (x = 0.10) thin films in high magnetic fields. We find an AF quantum phase transition near 60 T, where the Hall number jumps from nH =-x to nH = 1-x, resembling the change of nH at the AF boundary (xAF = 0.14) tuned by Ce doping. In the AF region a spin dependent state manifesting anomalous positive magnetoresistance is observed, which is closely related to superconductivity. Once the AF state is suppressed by magnetic field, a polarized ferromagnetic state is predicted, reminiscent of the recently reported ferromagnetic state at the quantum endpoint of the superconducting dome by Ce doping. The magnetic field that drives phase transitions in a similar but distinct manner to doping thereby provides a unique perspective to understand the quantum criticality of electron-doped cuprates.