Electron spin resonance inS=12antiferromagnets at high temperature

Abstract

We study the electron spin resonance of low-dimensional spin systems at high temperature and test the Kubo-Tomita theory of exchange narrowing. In finite-size systems ͑molecular magnets͒, we found a doublepeak resonance which strongly differs from the usual Lorentzian. For infinite systems, we have predictions for the linewidth and line shape as a function of the anisotropy strength. For this, we have used an interpolation between a nonperturbative calculation of the memory function at short times ͑exact diagonalization͒ and the hydrodynamic spin diffusion at long times. We show that the Dzyaloshinskii-Moriya anisotropies generally induce a much larger linewidth than the exchange anisotropies in two dimensions, contrary to the onedimensional case.

Quantum kagome frustrated antiferromagnets: One route to quantum spin liquids

“…Attributing all the ESR linewidth to this DM anisotropy yields an upper bound estimate of D p ∼ 0.01 J (negligible) and sizable D z ∼ 0.04-0.08 J [60,61], a common value in Cu oxides.…”

Dzyaloshinsky-Moriya interaction in vesignieite: A route to freezing in a quantum kagome antiferromagnet

“…[12][13][14] The mineral herbertsmithite, γ-ZnCu 3 (OH) 6 Cl 2 , believed so far to be the best realization of the QKA, 15 appears to be a spin liquid 9,16 sustaining spinon excitations, 17 in line with its DM anisotropy D z /J = 0.06(2). [18][19][20] Its location in the region close to the QCP is likely responsible for observed field- 21 and pressure-induced 22 freezing. This theoretical scenario awaits further validation, potentially by finding new compounds lying in the Néel-ordered region of the phase diagram.…”

Two-Dimensional Quantum Antiferromagnets

“…In fact the lack of inversion center on the magnetic bounds allows for Dzyaloshinskii-Moriya interaction of spin orbit origin. 334,335 These couplings have been estimated of the order of 0.08J, 351,355 not far from the theoretically expected quantum critical point. 352 The role of impurities in such a material has also been theoretically discussed.…”