A magnetic continuum observed by terahertz spectroscopy in a quantum spin liquid candidate BaCo$_2$(AsO$_4$)$_2$

Zhang, Xinshu; Xu, Yanyan; Halloran, T.; Zhong, Ruidan; Cava, R. J.; Broholm, C.; Drichko, N.; Armitage, N. P.

doi:10.48550/arxiv.2106.13418

Cited by 8 publications

(14 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The much smaller critical field of BaCo 2 (AsO 4 ) 2 was interpreted as an experimental demonstration that non-Kitaev interactions are indeed weaker in this 3d compound compared to the heavy transitionmetal based compounds. Recently, time-domain terahertz spectroscopy measurements [31] were argued to be consistent with the behavior expected for the Kitaev model.…”

mentioning

confidence: 57%

“…1 for the crystallographic structure) was suggested to be a particularly interesting reference compound [24][25][26][27][28][29]. This material manifests an antiferromagnetic ground state at ambient pressure below T N ≈ 5.4 K. Upon small in-plane magnetic fields (note that no discernable in-plane anisotropy was reported), two consecutive magnetic transitions at H1 ≈ 0.26 T and H2 ≈ 0.52 T at T = 1.8 K were observed, with the former corresponding to a transition into a ferrimagnetic state and the latter potentially giving rise to a moment bearing state that has no long-range order, but is still different from a trivial, fully saturated metamagnetic state, that might be in this case the realization of the Kitaev spin liquid [30,31]. This notion is motivated by the analogy of the temperature-field phase diagram to the one of α-RuCl 3 where in-plane fields of ∼ 80 kOe are needed to suppress magnetic order and where signatures of the Kitaev spin liquid might have been revealed [32].…”

mentioning

confidence: 88%

See 1 more Smart Citation

Hydrostatic pressure effect on Co-based honeycomb magnet BaCo2(AsO4)2

Huyan,

Schmidt,

Gati

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

The honeycomb antiferromagnet BaCo 2 (AsO 4 ) 2 , in which small in-plane magnetic fields (H1 ≈ 0.26 T and H2 ≈ 0.52 T at T = 1.8 K < T N ≈ 5.4 K) induce two magnetic phase transitions, has attracted attention as a possible candidate material for the realization of Kitaev physics based on the 3d element Co 2+ . Here, we report on the change of the transition temperature T N and the critical fields H1 and H2 of BaCo 2 (AsO 4 ) 2 with hydrostatic pressure up to ∼ 20 kbar, as determined from magnetization and specific heat measurements. Within this pressure range, a marginal increase of the magnetic ordering temperature is observed. At the same time, the critical fields are changed significantly (up to ∼ 25 -35 %). Specifically, we find that H1 is increased with hydrostatic pressure, i.e., the antiferromagnetic state is stabilized with hydrostatic pressure, whereas H2, which was previously associated with a transition into a proposed Kitaev spin liquid state, decreases with increasing pressure. These results put constraints on the magnetic models that are used to describe the low-temperature magnetic properties of BaCo 2 (AsO 4 ) 2 . I. INTRODUCTIONThe search for quantum spin liquids, a particularly exotic state of matter, has seen a boost over the last 15 years by the postulation of (i) the analytically exactly solvable Kitaev model [1] that hosts a spin-liquid ground state, as well as (ii) the Jackeli-Khaliullin approach to design Kitaev interactions in real materials [2]. The latter initially involved spin-orbitcoupled d 5 ions in an octahedral environment in Mott insulators, in which the combination of crystal field effects and spin-orbit coupling coupling generates an effective j eff = 1/2 moment. These moments are then coupled via bond-dependent ferromagnetic Ising interactions that are the central ingredient of the Kitaev model. Following these discoveries, the research concentrated on material realizations based on heavy, 4d and 5d, transition metals [3] due to their inherently large spin-orbit coupling. Prominent examples include Na 2 IrO 3 [4], α-Li 2 IrO 3 [5] and α-RuCl 3 [6]. All the listed materials show antiferromagnetic order at finite temperatures [7,8], which is thought to obscure the observation of the putative Kitaev spin liquid. The emergence of magnetic order is believed to originate from the presence of sizable non-Kitaev interactions [9, 10], such as nearest-neighbor and third nearest-neighbor Heisenberg couplings as well as off-diagonal couplings. The existence of these couplings is generally attributed to the spatial extent of the 4d and 5d orbitals which promotes longer-

show abstract

mentioning

confidence: 57%

mentioning

confidence: 88%

Hydrostatic pressure effect on Co-based honeycomb magnet BaCo2(AsO4)2

Huyan,

Schmidt,

Gati

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Generally, SOC in quantum magnets locks the spin rotation operations with the corresponding lattice rotations and hence reduce the continuous spin rotation symmetries to discrete ones. A class of spin-orbit coupled antiferromagnets on the honeycomb lattice has the discrete symmetry group D 3d [23][24][25][26][27] and contains anisotropic spin-spin interactions in addition to the isotropic Heisenberg exchanges (J terms). The anisotropic interactions include, the diagonal Kitaev type exchange terms S γ i S γ j (K terms) [28][29][30] and the off-diagonal exchange interactions such as the S α i S β j +S β i S α j interactions (Γ terms) 31,32 or the S α i S γ j + S γ i S α j + S β i S γ j + S γ i S β j interactions (Γ terms) [33][34][35][36] , here α, β, γ = x, y, z and we have only listed the interactions on the γ-bond.…”

Section: Symmetry Group Of the Spin Modelmentioning

confidence: 99%

Magnon Condensation in Dimerized Antiferromagnets with Spin-Orbit Coupling

Zhao,

Sun,

Liu

et al. 2021

Preprint

View full text Add to dashboard Cite

Bose-Einstein condensation (BEC) of triplet excitations triggered by a magnetic field, sometimes called magnon BEC, in dimerized antiferromagnets gives rise to a long-range antiferromagnetic order in the plane perpendicular to the applied magnetic field. To explore the effects of spin-orbit coupling on magnon condensation, we study the spin model on the distorted honeycomb lattice with dimerized Heisenberg exchange (J terms) and uniform off-diagonal exchange (Γ terms) interactions. By using variational Monte Carlo method and spin wave theory, we find that an out-of-plane magnetic field can induce different types of long-range magnetic orders, no matter if the ground state is a nonmagnetic dimerized state or an antiferromagnetically ordered Néel state. Furthermore, the critical properties of field-driven phase transitions in systems with spin-orbit coupling can be different from the conventional magnon BEC. Our study is helpful to understand the rich phases of spin-orbit coupled antiferromagnets in an external magnetic field.

show abstract

“…Among 3d-based honeycomb magnets, BaCo 2 (AsO 4 ) 2 (BCAO) has attracted a great deal of research interest recently. A couple of recent experimental studies have proposed BCAO as a candidate closest to the ideal Kitaev spin liquid [25,26]. It has been reported earlier in the literature that there is no magnetic order in BCAO down to 5.4 K. Below critical temperature, it shows a strong field and temperature-dependent magnetization with two successive magnetic transitions at the applied in-plane magnetic field of 0.26 T and 0.52 T [25].…”

Section: Introductionmentioning

confidence: 95%

“…A single crystal x-ray study reported that there is no stacking fault or formation of domains in BCAO [25]. A subsequent time domain spectroscopic study has suggested that BCAO has a dominant Kitaev interaction, where applying small inplane magnetic fields ∼ 0.5 T has been reported to drive the compound to a paramagnetic phase [26].…”

Section: Introductionmentioning

confidence: 99%

Active orbital degree of freedom and potential spin-orbit-entangled moments in Kitaev magnet candidate BaCo$_2$(AsO$_4$)$_2$

Samanta¹,

Detrattanawichai²,

Na-Phattalung³

et al. 2022

Preprint

View full text Add to dashboard Cite

Candidate materials for Kitaev spin liquid phase have been intensively studied recently because of their potential applications in fault-tolerant quantum computing. Although most of the studies on Kitaev spin liquid have been done in 4d and 5d based transition metal compounds, recently there has been a growing research interest in Co-based quasi-two-dimensional honeycomb magnets, such as BaCo2(AsO4)2 because of formation of spin-orbit-entangled J eff = 1/2 pseudospin moments at Co 2+ sites and potential realizations of Kitaev-like magnetism therein. Here, we obtain high-accuracy crystal and electronic structure of BaCo2(AsO4)2 by employing a combined density functional and dynamical mean-field theory calculations, which correctly capture the Mottinsulating nature of the target system. We show that Co 2+ ions form a high spin configuration, S = 3/2, with an active L eff = 1 orbital degree of freedom, in the absence of spin-orbit coupling. The size of trigonal distortion within CoO6 octahedra is found to be not strong enough to completely quench the orbital degree of freedom, so that the presence of spin-orbit coupling can give rise to the formation of spin-orbit-entangled moments and the Kitaev exchange interaction. Our finding supports recent studies on potential Kitaev magnetism in this compound and other Co-based layered honeycomb systems.

show abstract

A magnetic continuum observed by terahertz spectroscopy in a quantum spin liquid candidate BaCo$_2$(AsO$_4$)$_2$

Cited by 8 publications

References 36 publications

Hydrostatic pressure effect on Co-based honeycomb magnet BaCo2(AsO4)2

Hydrostatic pressure effect on Co-based honeycomb magnet BaCo2(AsO4)2

Magnon Condensation in Dimerized Antiferromagnets with Spin-Orbit Coupling

Active orbital degree of freedom and potential spin-orbit-entangled moments in Kitaev magnet candidate BaCo$_2$(AsO$_4$)$_2$

Contact Info

Product

Resources

About