Deformation of the triangular spin-12 lattice in Na2SrCo(PO4)2

  • Crystal structure and thermodynamic properties of Na2SrCo(PO4)2, the chemical sibling of the triangular quantum spin-liquid candidate Na2BaCo(PO4)2, are reported. From single crystal x-ray diffraction and high-resolution synchrotron x-ray powder diffraction, the compound was found to crystallize in the monoclinic space group P21/a at room temperature, in contrast to the trigonal Na2BaCo(PO4)2. Above 650 K, the symmetry of Na2SrCo(PO4)2 changes to C2/m, while around 1025 K a further transformation toward trigonal symmetry is observed. The monoclinic symmetry leads to a small deformation of the CoO6 octahedra beyond the trigonal distortion ubiquitous in this structure type and results in the stronger g-tensor anisotropy (gz/gxy=1.6) as well as the increased XXZ anisotropy (Jz/Jxy=2.1) compared to the Ba compound (gz/gxy=1.1, Jz/Jxy=1.5), while the average coupling strength, Jav/kB=(2Jxy+Jz)/3kB≃1.3K, remains unchanged. The Néel temperature increases from 140 mK (Ba) to 600 mK (Sr), andCrystal structure and thermodynamic properties of Na2SrCo(PO4)2, the chemical sibling of the triangular quantum spin-liquid candidate Na2BaCo(PO4)2, are reported. From single crystal x-ray diffraction and high-resolution synchrotron x-ray powder diffraction, the compound was found to crystallize in the monoclinic space group P21/a at room temperature, in contrast to the trigonal Na2BaCo(PO4)2. Above 650 K, the symmetry of Na2SrCo(PO4)2 changes to C2/m, while around 1025 K a further transformation toward trigonal symmetry is observed. The monoclinic symmetry leads to a small deformation of the CoO6 octahedra beyond the trigonal distortion ubiquitous in this structure type and results in the stronger g-tensor anisotropy (gz/gxy=1.6) as well as the increased XXZ anisotropy (Jz/Jxy=2.1) compared to the Ba compound (gz/gxy=1.1, Jz/Jxy=1.5), while the average coupling strength, Jav/kB=(2Jxy+Jz)/3kB≃1.3K, remains unchanged. The Néel temperature increases from 140 mK (Ba) to 600 mK (Sr), and an uncompensated in-plane moment of 0.066(4)μB/f.u. appears. We show that the ordering temperature of a triangular antiferromagnet is capably controlled by its structural distortions.show moreshow less

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Metadaten
Author:Vera P. Bader, Jan LangmannORCiDGND, Philipp GegenwartORCiDGND, Alexander A. TsirlinORCiDGND
URN:urn:nbn:de:bvb:384-opus4-984343
Frontdoor URLhttps://opus.bibliothek.uni-augsburg.de/opus4/98434
ISSN:2469-9950OPAC
ISSN:2469-9969OPAC
Parent Title (English):Physical Review B
Publisher:American Physical Society (APS)
Type:Article
Language:English
Year of first Publication:2022
Publishing Institution:Universität Augsburg
Release Date:2022/10/05
Volume:106
Issue:5
First Page:054415
DOI:https://doi.org/10.1103/physrevb.106.054415
Institutes:Mathematisch-Naturwissenschaftlich-Technische Fakultät
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Physik
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Physik / Lehrstuhl für Chemische Physik und Materialwissenschaften
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Physik / Lehrstuhl für Experimentalphysik VI
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):Deutsches Urheberrecht