Neutron spin-echo study of the critical dynamics of spin-52 antiferromagnets in two and three dimensions

K. F. Tseng, T. Keller, A. C. Walters, R. J. Birgeneau, and B. Keimer
Phys. Rev. B 94, 014424 – Published 19 July 2016

Abstract

We report a neutron spin-echo study of the critical dynamics in the S=52 antiferromagnets MnF2 and Rb2MnF4 with three-dimensional (3D) and two-dimensional (2D) spin systems, respectively, in zero external field. Both compounds are Heisenberg antiferromagnets with a small uniaxial anisotropy resulting from dipolar spin-spin interactions, which leads to a crossover in the critical dynamics close to the Néel temperature, TN. By taking advantage of the μeV energy resolution of the spin-echo spectrometer, we have determined the dynamical critical exponents z for both longitudinal and transverse fluctuations. In MnF2, both the characteristic temperature for crossover from 3D Heisenberg to 3D Ising behavior and the exponents z in both regimes are consistent with predictions from the dynamical scaling theory. The amplitude ratio of longitudinal and transverse fluctuations also agrees with predictions. In Rb2MnF4, the critical dynamics crosses over from the expected 2D Heisenberg behavior for TTN to a scaling regime with exponent z=1.387(4), which has not been predicted by theory and may indicate the influence of long-range dipolar interactions.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
3 More
  • Received 22 May 2016

DOI:https://doi.org/10.1103/PhysRevB.94.014424

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

K. F. Tseng1,2, T. Keller1,2, A. C. Walters1,3, R. J. Birgeneau4, and B. Keimer1,*

  • 1Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
  • 2Max Planck Society Outstation at the Forschungsneutronenquelle Heinz Maier-Leibnitz (MLZ), D-85747 Garching, Germany
  • 3Diamond Light Source Limited, Chilton, Didcot, Oxfordshire OX11 0DE, United Kingdom
  • 4Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

  • *To whom correspondence should be addressed: b.keimer@fkf.mpg.de

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 94, Iss. 1 — 1 July 2016

Reuse & Permissions
Access Options
CHORUS

Article Available via CHORUS

Download Accepted Manuscript
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×