Tuning the disorder of superglasses

Abstract

We study the interplay of superfluidity, glassy and magnetic orders of hardcore bosons with random frustrating interactions. In the classical limit, this model reduces to a $\pm J$ Edwards-Anderson Ising model with concentration $p$ of the ferromagnetic bonds, which hosts a glassy-ferromagnetic transition at a critical concentration $p_c^{\rm cl}\sim 0.77$ on a 3D cubic lattice. Our quantum Monte Carlo simulation results using the worm algorithm show that quantum fluctuations stabilize the coexistence of superfluidity and glassy order ("superglass"), and shift the (super)glassy-ferromagnetic transition to $p_c> p_c^{\rm cl}$. In contrast, antiferromagnetic order coexists with superfluidity to form a supersolid, and the transition to the glassy phase occurs at a higher $p$.