A two-dimensional spin liquid in quantum kagome ice

Abstract

Actively sought since the turn of the century, two-dimensional quantum spin liquids (QSLs) are exotic phases of matter where magnetic moments remain disordered even at zero temperature. Despite ongoing searches, QSLs remain elusive, due to a lack of concrete knowledge of the microscopic mechanisms that inhibit magnetic order in materials. Here we study a model for a broad class of frustrated magnetic rare-earth pyrochlore materials called quantum spin ices. When subject to an external magnetic field along the [111] crystallographic direction, the resulting interactions contain a mix of geometric frustration and quantum fluctuations in decoupled two-dimensional kagome planes. Using quantum Monte Carlo simulations, we identify a set of interactions sufficient to promote a groundstate with no magnetic long-range order, and a gap to excitations, consistent with a Z 2 spin liquid phase. This suggests an experimental procedure to search for two-dimensional QSLs within a class of pyrochlore quantum spin ice materials.

Designing Frustrated Quantum Magnets with Laser-Dressed Rydberg Atoms

“…1(c). This illustrates the design of kagome quantum spin ice (J +-= 0) [10] for realistic atomic parameters. As discussed below, an angular dependence of J α can be obtained by inclining the laser beams [14].…”

“…The diagonal J z interaction is steplike with a repulsive (antiferromagnetic) soft core at small distances, ρ < 2 µm, and an attractive (ferromagnetic tail) at long distances. The spin flip term J ++ is peaked at ρ ≈ 2.5 µm while J +-= 0, thus realizing the Hamiltonian of quantum spin ice on a kagome lattice [10] at a lattice spacing a = 1.8 µm. The lifetime of the 60P 1/2 Rydberg state including blackbody radiation at T = 300 K is τ 60 = 133 µs [17] which yields an effective ground state decay rate of…”

“…This finds immediate application in the context of extended quantum ice models [19], as illustrated in Fig. 1 for kagome quantum spin ice [10]. Within the same geometry, moving away from the ∆ + = −∆ -regime, a finite J +-can be switched on, and extended XY Z models can be realized [11,20].…”

“…(c) Spin interactions Jα of Eq. (1) as a function of distance ρ realizing quantum spin ice on a kagome lattice [10]. Red (gray) dotted lines indicate NN and NNN interactions [red (gray) arrows in panel (a)].…”

“…1: on a kagome lattice, different coupling realizations of Eq. (1) encompass a variety of physical models, including kagome quantum spin ice (requiring J +-= 0) [10] and extended XY Z models [11]. These models encompass a prototypical feature of frustrated quantum magnets, i.e., the emergence of dynamical gauge fields [1].…”