Phase Diagram of YbZnGaO4 in Applied Magnetic Field

Abstract

Recently, Yb-based triangular lattice antiferromagnets have garnered significant interest as possible quantum spin liquid candidates. One example is YbMgGaO 4 , which showed many promising spin liquid features, but also possesses a high degree of disorder owing to site-mixing between the non-magnetic cations. To further elucidate the role of chemical disorder and to explore the phase diagram of these materials in applied field, we present neutron scattering and sensitive magnetometry measurements of the closely related compound, YbZnGaO 4 . Our results suggest a difference in magnetic anisotropy between the two compounds, and we use key observations of the magnetic phase crossover to motivate an exploration of the field-and exchange parameter-dependent phase diagram, providing an expanded view of the available magnetic states in applied field. This enriched map of the phase space serves as a basis to restrict the values of parameters describing the magnetic Hamiltonian with broad application to recently discovered related materials.

Stripe-yz magnetic order in the triangular-lattice antiferromagnet KCeS2

“…We also find that, surprisingly, plain-vanilla DFT model at PBE/PAW level with explicit 4f 1 treatment correctly predicts the dominance of AFM phase over FM with the reasonable magnetization density and the difference in energy between AFM and FM configurations of 2 meV/Ce, which is remarkably close to the mean isotropic coupling, (J xx + J yy + J zz )/3 = 2.1 meV/Ce. Furthermore, comparing the ratio of J i j components in our model with the recent group-theoretical study with a pseudospin-1/2 moment model on a similar lattice [57,63], we find that with J yz /J xx ∼ 1 the KCeS 2 system should be deep in the stripe-yz region of the phase diagram, in consistency with our experimental spin structure.…”

“…The refinement suggests a statistically insignificant out-of-plane canting of Ce 3+ spins by (5.5 ± 5) • , yet fixing this angle to zero has no significant effect on the quality of the fit, so also the in-plane spin arrangement would be consistent with our data. This type of AFM structure on the triangular lattice is known as "stripe-yz" order among theorists [56,57,63,64]. The stacking of the AFM layers along the out-of-plane direction is illustrated in Fig.…”

Stripe-yz magnetic order in the triangular-lattice antiferromagnet KCeS2

“…We also find that, surprisingly, plain-vanilla DFT model at PBE/PAW level with explicit 4 f 1 treatment correctly predicts the dominance of AFM phase over FM with the reasonable magnetization density and the difference in energy between AFM and FM configurations of 2 meV/Ce, which is remarkably close to the mean isotropic coupling, (J xx + J yy + J zz )/3 = 2.1 meV/Ce. Furthermore, comparing the ratio of J i j components in our model with the recent group-theoretical study with a pseudospin-1/2 moment model on a similar lattice [57,63], we find that with J yz /J xx ∼ 1 the KCeS 2 system should be deep in the stripe-yz region of the phase diagram, in consistency with our experimental spin structure.…”

“…The refinement suggests a statistically insignificant out-of-plane canting of Ce 3+ spins by (5.5 ± 5) • , yet fixing this angle to zero has no significant effect on the quality of the fit, so also the in-plane spin arrangement would be consistent with our data. This type of AFM structure on the triangular lattice is known as 'stripe-yz' order among theorists [56,57,63,64]. The stacking of the AFM layers along the out-of-plane direction is illustrated in figure 2(e).…”