Magnetization process and ordering of the S=1/2 pyrochlore Heisenberg antiferromagnet in a magnetic field

We study the S = 12 pyrochlore Heisenberg antiferromagnet in a magnetic field. Using large-scale density -matrix renormalization group calculations for clusters with up to 128 spins, we find indications of a finite triplet gap, causing a threshold field to nonzero magnetization in the magnetization curve. We obtain a robust saturation field consistent with a magnon crystal, although the corresponding 5/6 magnetization plateau is very slim and possibly unstable. Most remarkably, there is a pronounced and apparently robust 1/2 magnetization plateau where the ground state breaks the rotational symmetry of the lattice, exhibiting oppositely polarized spins on alternating kagome and triangular planes. Reminiscent of the kagome ice plateau of the pyrochlore Ising antiferromagnet known as spin ice, it arises via a much more subtle quantum order by disorder mechanism.

Automated summary

This study focuses on the investigation of the pyrochlore Heisenberg antiferromagnet in a magnetic field, revealing interesting magnetic behaviors such as a finite triplet gap and a stable 1/2 magnetization plateau.