Quantum versus thermal fluctuations in the fcc antiferromagnet: Alternative routes to order by disorder

Schick, R.; Ziman, Timothy; Zhitomirsky, M. E.

doi:10.1103/physrevb.102.220405

Cited by 21 publications

(21 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This effect was recently studied in Ref. [29] in the case of the nearest-neighbor Heisenberg model on the fcc lattice. [Recall that this model hosts a degenerate line of spiral ground states (phase i2 in our notations).]…”

Section: Application To the Anisotropic Modelmentioning

confidence: 98%

“…These orders, which are a superposition of spiral states, are notoriously difficult to stabilize in real antiferromagnets. Moreover, even when they appear as classical ground states degenerate with other collinear ones, fluctuations (thermal and quantum) are expected to lift the degeneracy in favor of the latter via the so-called "order-bydisorder" mechanism [25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Anisotropic exchange and non-collinear antiferromagnets on a noncentrosymmetric fcc structure as in the half-Heuslers

Diop,

Jackeli,

Savary

2021

Preprint

View full text Add to dashboard Cite

The face-centered cubic (fcc) antiferromagnet is a typical example of a geometrically frustrated system in three dimensions: the classical nearest-neighbor fcc Heisenberg model exhibits a ground state manifold with large accidental degeneracy. Here, we study the most general nearest-and nextnearest-neighbor exchange model allowed by the space-group symmetry of the noncentrosymmetric half-Heusler compounds, which includes a variety of anisotropic coupling terms. We show that, while the so-called Kitaev and symmetric off-diagonal (Γ) interactions do not fully lift the accidental ground state degeneracy of the isotropic J1-J2 model, Dzyaloshinskii-Moriya interactions which are allowed in the half-Heuslers unambiguously select a noncollinear ground state. We then discuss the role of other effects in the ground state selection, such as quantum fluctuations and the coupling to a magnetic field, and show that these effects can stabilize noncoplanar (triple-q) orders. These results suggest that some half-Heusler antiferromagnets might host rare noncollinear/noncoplanar orders, which may in turn affect the transport properties of these semimetals.

show abstract

Section: Application To the Anisotropic Modelmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Anisotropic exchange and non-collinear antiferromagnets on a noncentrosymmetric fcc structure as in the half-Heuslers

Diop,

Jackeli,

Savary

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…We also track the influence of different structural distortions on this parameter by monitoring ∆ upon cooling whilst the compound progressively reduces its symmetry via two consecutive structural phase transitions. K 2 IrBr 6 belongs to the family of Ir 4+ antifluorites, material realizations of frustrated spin- 1 2 fcc antiferromagnets [13][14][15], and we also investigate how symmetry lowering changes the strength of electronic correlations and magnetic couplings as well as the magnitude of magnetic frustration in this family of compounds.…”

Section: Introductionmentioning

confidence: 99%

Toward cubic symmetry for Ir$^{4+}$: structure and magnetism of antifluorite K$_2$IrBr$_6$

Khan,

Prishchenko,

Upton

et al. 2021

Preprint

View full text Add to dashboard Cite

Crystal structure, electronic state of Ir 4+ , and magnetic properties of the antifluorite compound K2IrBr6 are studied using high-resolution synchrotron x-ray diffraction, resonant inelastic x-ray scattering (RIXS), thermodynamic and transport measurements, and ab initio calculations. The crystal symmetry is reduced from cubic at room temperature to tetragonal below 170 K and eventually to monoclinic below 122 K. These changes are tracked by the evolution of the non-cubic crystal-field splitting ∆ measured by RIXS. Non-monotonic changes in ∆ are ascribed to the competing effects of the tilt, rotation, and deformation of the IrBr6 octahedra as well as tetragonal strain on the electronic levels of Ir 4+ . The Néel temperature of TN = 11.9 K exceeds that of the isostructural K2IrCl6, and the magnitude of frustration on the fcc spin lattice decreases. We argue that the replacement of Cl by Br weakens electronic correlations and enhances magnetic couplings.

show abstract

“…1(b)]. The presence of possible frustration in fcc lattices is interesting in its own right as it shows an intricate competition of magnetic ground states, even in the absence of Kitaev or any other exchange anisotropy [25][26][27]. In contrast to many other iridates, these compounds are available as relatively large single crystals amenable to lab spectroscopic probes, featuring a cubic symmetry of the molecule that not only ensures the spin-orbit-coupled j eff = 1 2 state of the Ir 4+ ions, but also restricts the number of relevant interaction parameters.…”

mentioning

confidence: 99%

“…Together with two other equivalent Q, obtained by permutation of Q x,y,z , there are in total six domains for the type-III collinear structure. Following a recent theoretical study of the excitation spectra in fcc antiferromagnets [26], we have performed linear spin-wave calculations for the Hamiltonian (2) with J 2 , K > 0. The ESR response corresponds to long wavelength excitations with k → 0.…”

mentioning

confidence: 99%

Antiferromagnetic resonance in the cubic iridium hexahalides (NH$_4$)$_2$IrCl$_6$ and K$_2$IrCl$_6$

Bhaskaran,

Ponomaryov,

Wosnitza

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

We report on high-field electron spin resonance studies of two iridium hexahalide compounds, (NH4)2IrCl6 and K2IrCl6. In the paramagnetic state, our measurements reveal isotropic g-factors g = 1.79(1) for the Ir 4+ ions, in agreement with their cubic symmetries. Most importantly, in the magnetically ordered state, we observe two magnon modes with zero-field gaps of 11.3 and 14.2 K for (NH4)2IrCl6 and K2IrCl6, respectively. Based on that and using linear spin-wave theory, we estimate the nearest-neighbor exchange couplings and anisotropic Kitaev interactions, J1/kB = 10.3 K, K/kB = 0.7 K for (NH4)2IrCl6, and J1/kB = 13.8 K, K/kB = 0.9 K for K2IrCl6, revealing the nearest-neighbor Heisenberg coupling as the leading interaction term, with only a weak Kitaev anisotropy.

show abstract

Quantum versus thermal fluctuations in the fcc antiferromagnet: Alternative routes to order by disorder

Cited by 21 publications

References 68 publications

Anisotropic exchange and non-collinear antiferromagnets on a noncentrosymmetric fcc structure as in the half-Heuslers

Anisotropic exchange and non-collinear antiferromagnets on a noncentrosymmetric fcc structure as in the half-Heuslers

Toward cubic symmetry for Ir$^{4+}$: structure and magnetism of antifluorite K$_2$IrBr$_6$

Antiferromagnetic resonance in the cubic iridium hexahalides (NH$_4$)$_2$IrCl$_6$ and K$_2$IrCl$_6$

Contact Info

Product

Resources

About