Possible inversion symmetry breaking in the $S=1/2$ pyrochlore Heisenberg magnet

Understand

We address the ground-state properties of the long-standing and much-studied three-dimensional quantum spin liquid candidate, the $S=\frac 1 2$ pyrochlore Heisenberg antiferromagnet.

• By using $SU(2)$ density-matrix renormalization group (DMRG), we are able to access cluster sizes of up to 128 spins.
• Our most striking finding is a robust spontaneous inversion symmetry breaking, reflected in an energy density difference between the two sublattices of tetrahedra, familiar as a starting point of earlier perturbative treatments.
• We also determine the ground-state energy, $E_0/N_\text{sites} = -0.490(6) J$, by combining extrapolations of DMRG with those of a numerical linked cluster expansion.