Electron spin resonance inS=12antiferromagnetic chains

Abstract

A systematic field-theory approach to Electron Spin Resonance (ESR) in the S = 1/2 quantum antiferromagnetic chain at low temperature T (compared to the exchange coupling J) is developed. In particular, effects of a transverse staggered field h and an exchange anisotropy (including a dipolar interaction) δ on the ESR lineshape are discussed. In the lowest order of perturbation theory, the linewidth is given as ∝ Jh 2 /T 2 and ∝ (δ/J) 2 T , respectively. In the case of a transverse staggered field, the perturbative expansion diverges at lower temperature; non-perturbative effects at very low temperature are discussed using exact results on the sine-Gordon field theory. We also compare our field-theory results with the predictions of Kubo-Tomita theory for the high-temperature regime, and discuss the crossover between the two regimes. It is argued that a naive application of the standard Kubo-Tomita theory to the Dzyaloshinskii-Moriya interaction gives an incorrect result. A rigorous and exact identity on the polarization dependence is derived for certain class of anisotropy, and compared with the field-theory results.

Site-selective quantum correlations revealed by magnetic anisotropy in the tetramer system SeCuO3

“…26 This was later explained as a consequence of the Dzyaloshinsky-Moriya interaction (DMI) within the Oshikawa-Affleck (OA) theory of ESR in spin S = 1/2 Heisenberg chains. 20,27 Similar g shift was documented and explained within the OA theory in 1D Cu pyrimidine dinitrate. 28 However, in SeCuO 3 the g shift saturates below 50 K only to increase again in the vicinity of the phase transition to long-range order.…”

“…More recently Oshikawa and Affleck (OA) have developed a model to cover the deficiency of the KT theory at low T in S = 1/2 AFM Heisenberg chains. 20 Since SeCuO 3 has two distinct copper site, neither the OA model can be applied.…”

Spin-orbit-mediated spin relaxation in monolayer MoS2

“…33 The expectation values in Eqs. (7) and (8) refer to the Hamiltonian without the SO coupling terms.…”

Spin dynamics in theS=12antiferromagnetic chain compoundsδ−(Náfrádi1, Olariu2, Forró3 et al. 2010Phys. Rev. B170160View full textAdd to dashboardCite

“…The perturbation HЈ due to an exchange anisotropy or a staggered effective field shifts and broadens the ESR line. The temperature dependence of the ESR line width of an anisotropic exchange coupled chain with HЈ = H ea = JЈ͚ j=1 N S j p S j+1 p , where an anisotropy axis is along p, was calculated 8,9 in the g e B B 0 Ӷ k B T Ӷ J ʈ parameter range…”

“…[7][8][9] The calculations are for chains where a staggered field alternating along the chain is added to a weakly anisotropic antiferromagnetic exchange interaction that is uniform for all molecules. In real materials there is always some exchange anisotropy or a dipolar field.…”