Magnetic properties of lightly doped antiferromagnetic YBa$_{2}$Cu$_{3}$O$_{y}$

TL;DR

This study investigates the magnetic properties of lightly doped YBa₂Cu₃O_y, revealing that antiferromagnetic order persists with stable staggered magnetization despite doping, and explains these phenomena through the physics of a lightly doped Mott insulator.

Contribution

It provides a detailed analysis of magnetic behavior in lightly doped YBa₂Cu₃O_y, highlighting the stability of staggered magnetization and the rapid decay of Neel temperature, advancing understanding of doped Mott insulators.

Findings

Staggered magnetization remains nearly constant with doping.

Neel temperature decreases rapidly to zero at 6% doping.

Antiferromagnetic order is stable below 6% doping due to Mott insulator physics.

Abstract

The present work addresses YBa$_{2}$Cu$_{3}$O$_{y}$ at doping below x=6% where the compound is a collinear antiferromagnet. In this region YBa$_{2}$Cu$_{3}$O$_{y}$ is a normal conductor with a finite resistivity at zero temperature. The value of the staggered magnetization at zero temperature is 0.6\mu_B, the maximum value allowed by spin quantum fluctuations. The staggered magnetization is almost independent of doping. On the other hand, the Neel temperature decays very quickly from T_N=420K at x=0 to practically zero at x = 0.06. The present paper explains these remarkable properties and demonstrates that the properties result from the physics of a lightly doped Mott insulator with small hole pockets. Nuclear quadrupole resonance data are also discussed. The data shed light on mechanisms of stability of the antiferromagnetic order at x < 6%.