$S=2$ quasi-one-dimensional spin waves in CrCl${}_{2}$

$S = 2$ quasi-one-dimensional spin waves in CrCl $_{2}$

M. B. Stone, G. Ehlers, and G. E. Granroth

Phys. Rev. B 88, 104413 – Published 16 September 2013

Abstract

We examine the magnetic excitation spectrum in the $S = 2$ Heisenberg antiferromagnet CrCl $_{2}$ . Inelastic neutron scattering measurements on powder samples are able to determine the significant exchange interactions in this system. A large anisotropy gap is observed in the spectrum below the Néel temperature and the ratio of the two largest exchange constants is $J_{c} / J_{b} = 9.1 \pm 2.2$ . However, no sign of a gapped quantum spin liquid excitation was found in the paramagnetic phase.

Received 11 June 2013

DOI:https://doi.org/10.1103/PhysRevB.88.104413

Authors & Affiliations

M. B. Stone, G. Ehlers, and G. E. Granroth

Quantum Condensed Matter Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

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Issue

Vol. 88, Iss. 10 — 1 September 2013

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Images

Figure 1
Nuclear and magnetic structure of CrCl $_{2}$ .[32, 33] Open circles represent Cr atomic sites and gray circles represent Cl atomic sites. Proposed exchange constants along the $a$ , $b$ , and $c$ directions are illustrated with arrows in the left unit cell. Cr-Cl and Cl-Cl bonding are shown on the right side of the figure. The phase of the ordered moments on the Cr sites is shown using $+$ and $-$ symbols. Dashed lines correspond to the nuclear unit cell.Reuse & Permissions
Figure 2
Inelastic scattering intensity as a function of energy and wave-vector transfer for CrCl $_{2}$ . Measurements were made at $T = 5$ K. (a) Data from ARCS measured with $E_{i} = 15$ meV. Top axis corresponds to wave-vector transfer. (b) Data from SEQUOIA measured with $E_{i} = 15$ meV. Bottom axis corresponds to wave-vector transfer. (c) Data from CNCS measured with $E_{i} = 4.2$ meV. Bottom axis corresponds to wave-vector transfer. Data in (c) have been background subtracted using an empty aluminum sample can measurement.Reuse & Permissions
Figure 3
Neutron diffraction measurements of CrCl $_{2}$ as a function of temperature. Measurements are from the CNCS spectrometer for $E_{i} = 4.2$ meV integrated between $- 4$ and 4 meV energy transfer. Data have been background subtracted using an empty aluminum sample can measurement. (a) Scattering intensity at four select temperatures. (b) Temperature- and wave-vector-dependent scattering intensity for warming the sample. (c) Integrated scattering intensity for warming (solid symbols) and cooling (open symbols). Data have been integrated with a total width in wave-vector transfer of $Δ Q = 0.04$ Å $^{- 1}$ . Solid and dotted lines correspond to power-law fits between 13 and 43 K as described in the text.Reuse & Permissions
Figure 4
(a) Image plot of the scattering intensity as a function of energy and wave-vector transfer for CrCl $_{2}$ at $T = 5$ K as measured using the SEQUOIA instrument. (b) Calculated scattering intensity including $J_{c}$ and $D$ fitting parameters as described in the text. (c) Calculated scattering intensity including $J_{c}$ , $D$ , and $J_{b}$ fitting parameters as described in the text. (d) Calculated scattering intensity including $J_{c}$ , $D$ , $J_{b}$ , and $J_{a}$ fitting parameters as described in the text.Reuse & Permissions
Figure 5
Energy- and wave-vector-dependent scattering intensity for CrCl $_{2}$ at four temperatures. Data were measured using the ARCS instrument.Reuse & Permissions
Figure 6
Energy-dependent scattering intensity for CrCl $_{2}$ as a function of temperature. Data were integrated between 0.9 and 1.2 inverse angstroms in wave-vector transfer. Data were measured using the CNCS instrument.Reuse & Permissions

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