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Title: Short-range order in the quantum XXZ honeycomb lattice material BaCo 2 ( PO 4 ) 2

Abstract

In this paper, we present observations of highly frustrated quasi-two-dimensional (2D) magnetic correlations in the honeycomb lattice layers of the S eff =1/2 compound γ-BaCo 2(PO 4) 2 (γ-BCPO). Specific heat shows a broad peak comprised of two weak kink features at T N1~6 K and T N2~3.5 K, the relative weights of which can be modified by sample annealing. Neutron powder diffraction measurements reveal short range quasi-2D order that is established below T N1 and T N2, at which two separate, incompatible, short range magnetic orders onset: commensurate antiferromagnetic correlations with correlation length ξ c=60±2 Å (T N1) and in quasi-2D helical domains with ξ h=350±11 Å (T N2). The ac magnetic susceptibility response lacks frequency dependence, ruling out spin freezing. Inelastic neutron scattering data on γ-BCPO is compared with linear spin wave theory, and two separate parameter regions of the XXZ J 1-J 2-J 3 model with ferromagnetic nearest-neighbor exchange J 1 are favored, both near regions of high classical degeneracy. High energy coherent excitations (~10 meV) persist up to at least 40 K, suggesting strong in-plane correlations persist above TN. Finally, these data show that γ-BCPO is a rare highly frustrated, quasi-2D S eff =1/2 honeycomb latticemore » material which resists long range magnetic order and spin freezing.« less

Authors:
 [1];  [1];  [1];  [1];  [1]; ORCiD logo [2];  [3];  [4]
  1. Colorado State Univ., Fort Collins, CO (United States). Department of Physics
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division
  3. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
  4. Colorado State Univ., Fort Collins, CO (United States). Department of Physics; Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario (Canada). Quantum Materials Program
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1435190
Alternate Identifier(s):
OSTI ID: 1432902
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 13; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Nair, Harikrishnan S., Brown, J, Coldren, E., Hester, G., Gelfand, M., Podlesnyak, Andrey A., Huang, Q., and Ross, K. A.. Short-range order in the quantum XXZ honeycomb lattice material BaCo2(PO4)2. United States: N. p., 2018. Web. doi:10.1103/PhysRevB.97.134409.
Nair, Harikrishnan S., Brown, J, Coldren, E., Hester, G., Gelfand, M., Podlesnyak, Andrey A., Huang, Q., & Ross, K. A.. Short-range order in the quantum XXZ honeycomb lattice material BaCo2(PO4)2. United States. doi:10.1103/PhysRevB.97.134409.
Nair, Harikrishnan S., Brown, J, Coldren, E., Hester, G., Gelfand, M., Podlesnyak, Andrey A., Huang, Q., and Ross, K. A.. Thu . "Short-range order in the quantum XXZ honeycomb lattice material BaCo2(PO4)2". United States. doi:10.1103/PhysRevB.97.134409.
@article{osti_1435190,
title = {Short-range order in the quantum XXZ honeycomb lattice material BaCo2(PO4)2},
author = {Nair, Harikrishnan S. and Brown, J and Coldren, E. and Hester, G. and Gelfand, M. and Podlesnyak, Andrey A. and Huang, Q. and Ross, K. A.},
abstractNote = {In this paper, we present observations of highly frustrated quasi-two-dimensional (2D) magnetic correlations in the honeycomb lattice layers of the Seff =1/2 compound γ-BaCo2(PO4)2 (γ-BCPO). Specific heat shows a broad peak comprised of two weak kink features at TN1~6 K and TN2~3.5 K, the relative weights of which can be modified by sample annealing. Neutron powder diffraction measurements reveal short range quasi-2D order that is established below TN1 and TN2, at which two separate, incompatible, short range magnetic orders onset: commensurate antiferromagnetic correlations with correlation length ξc=60±2 Å (TN1) and in quasi-2D helical domains with ξh=350±11 Å (TN2). The ac magnetic susceptibility response lacks frequency dependence, ruling out spin freezing. Inelastic neutron scattering data on γ-BCPO is compared with linear spin wave theory, and two separate parameter regions of the XXZ J1-J2-J3 model with ferromagnetic nearest-neighbor exchange J1 are favored, both near regions of high classical degeneracy. High energy coherent excitations (~10 meV) persist up to at least 40 K, suggesting strong in-plane correlations persist above TN. Finally, these data show that γ-BCPO is a rare highly frustrated, quasi-2D Seff =1/2 honeycomb lattice material which resists long range magnetic order and spin freezing.},
doi = {10.1103/PhysRevB.97.134409},
journal = {Physical Review B},
number = 13,
volume = 97,
place = {United States},
year = {Thu Apr 12 00:00:00 EDT 2018},
month = {Thu Apr 12 00:00:00 EDT 2018}
}

Journal Article:
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