Quantum Fluctuations Suppress the Critical Fields in BaCo$_2$(AsO$_4$)$_2$

• DOI: 10.48550/arxiv.2403.15315
• Publication Date: 2024-03-22
• Authors: Shiva Safari; William Bateman-H...; Asimpunya Mitra; Félix Desrochers; Emily Z. Zhang; Lubuna Shafeek; Austin M. Ferrenti; Tyrel M. McQueen; Arkady Shekhter; Zoltán Köllö; Yong Baek Kim; B. J. Ramshaw; K. A. Modic
• Keywords: Condensed Matter - Strongly Correlated Electrons; Quantum Physics; Strongly Correlated Electrons (cond-mat.str-el); FOS: Physical sciences; Quantum Physics (quant-ph)

Early efforts to realize exotic quantum ground states in frustrated magnets focused on frustration arising from the lattice geometry alone. Attention has shifted bond-dependent anisotropic interactions, as well further-neighbor non-geometrically-frustrated lattices due their greater versatility. The honeycomb magnet BaCo$_2$(AsO$_4$)$_2$ recently emerged a candidate host for both (e.g. Kitaev) and third-neighbor ($J_3$) become model experimental system its relatively low levels of disorder. Understanding relative importance different exchange interactions holds key achieving novel states, such spin liquids. Here, we use magnetotropic susceptibility map out intermediate high-field phase diagram function out-of-plane magnetic field direction at $T = 1.6$ K. We show that data are qualitatively consistent with classical Monte Carlo results XXZ-$J_1$-$J_3$ small Kitaev off-diagonal couplings included. However, calculated critical fields systematically larger than values. Infinite-DMRG computations reveal corrections nearby ferromagnetic state likely responsible suppressed fields. Together, our experiment theory analyses demonstrate that, while fluctuations play an important role determining diagram, most physics can be understood terms dynamics long-range ordered leaving little room possibility liquid.