Frustrated impurity spins in ordered two-dimensional quantum antiferromagnets
| dc.creator | Syromyatnikov, A. V. | |
| dc.creator | Maleyev, S. V. | |
| dc.date | 2006-10-18 | |
| dc.date.accessioned | 2026-07-07T07:27:35Z | |
| dc.date.available | 2026-07-07T07:27:35Z | |
| dc.description | Dynamical properties of an impurity spin coupled symmetrically to sublattices of ordered 2D Heisenberg quantum antiferromagnet (i.e., frustrated impurity spin) are discussed at $T\ge0$ (existence of a small interaction stabilizing the long range order at $T\ne0$ is implied). We continue our study on this subject started in Phys.Rev.B 72, 174419 (2005), where spin-1/2 defect is discussed and the host spins fluctuations are considered within the spin-wave approximation (SWA). In the present paper we i) go beyond SWA and ii) study impurities with spins $S\ge1/2$. It is demonstrated that in contrast to defects coupled to sublattices asymmetrically longitudinal host spins fluctuations play important role in the frustrated impurity dynamics. The spectral function, that is proportional to $ω^2$ within SWA, acquires new terms proportional to $ω^2$ and $ωT^2$. It is observed that the spin-1/2 impurity susceptibility has the same structure as that obtained within SWA: the Lorenz peak and the non-resonant term. The difference is that the width of the peak becomes larger being proportional to $f^2(T/J)^3$ rather than $f^4(T/J)^3$, where $f$ is the dimensionless coupling parameter. We show that transverse static susceptibility acquires a new negative logarithmic contribution. In accordance with previous works we find that host spins fluctuations lead to an effective one-ion anisotropy on the impurity site. Then defects with $S>1/2$ appears to be split. We observe strong reduction of the value of the splitting due to longitudinal host spins fluctuations. We demonstrate that the dynamical impurity susceptibility contains $2S$ Lorenz peaks corresponding to transitions between the levels, and the non-resonant term. | |
| dc.description | 17 pages, 7 figures, to appear in PRB | |
| dc.identifier | https://arxiv.org/abs/cond-mat/0610506 | |
| dc.identifier | http://arxiv.org/abs/cond-mat/0610506 | |
| dc.identifier | Phys. Rev. B 74, 184433 (2006) | |
| dc.identifier | doi:10.1103/PhysRevB.74.184433 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/117426 | |
| dc.subject | Strongly Correlated Electrons | |
| dc.title | Frustrated impurity spins in ordered two-dimensional quantum antiferromagnets | |
| dc.type | text |