Orbital dimer model for a spin-glass state in Y2Mo2O7
The formation of a spin glass generally requires that magnetic exchange interactions are both frustrated and disordered. Consequently, the origin of spin-glass behavior in Y2Mo2O7—in which magnetic Mo4þ ions occupy a frustrated pyrochlore lattice with minimal compositional disorder—has been a longst...
| Main Authors: | , , , , , , , , , |
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| Format: | Journal article |
| Published: |
American Physical Society
2016
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| _version_ | 1797064394165714944 |
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| author | Thygesen, P Paddison, J Zhang, R Beyer, K Chapman, K Playford, H Tucker, M Keen, D Hayward, M Goodwin, A |
| author_facet | Thygesen, P Paddison, J Zhang, R Beyer, K Chapman, K Playford, H Tucker, M Keen, D Hayward, M Goodwin, A |
| author_sort | Thygesen, P |
| collection | OXFORD |
| description | The formation of a spin glass generally requires that magnetic exchange interactions are both frustrated and disordered. Consequently, the origin of spin-glass behavior in Y2Mo2O7—in which magnetic Mo4þ ions occupy a frustrated pyrochlore lattice with minimal compositional disorder—has been a longstanding question. Here, we use neutron and x-ray pair-distribution function (PDF) analysis to develop a disorder model that resolves apparent incompatibilities between previously reported PDF, extended x-rayabsorption fine structure spectroscopy, and NMR studies, and provides a new and physical explanation of the exchange disorder responsible for spin-glass formation. We show that Mo4þ ions displace according to a local “two-in–two-out” rule on each Mo4 tetrahedron, driven by orbital dimerization of Jahn-Teller active Mo4þ ions. Long-range orbital order is prevented by the macroscopic degeneracy of dimer coverings permitted by the pyrochlore lattice. Cooperative O2− displacements yield a distribution of Mo–O–Mo angles, which in turn introduces disorder into magnetic interactions. Our study demonstrates experimentally how frustration of atomic displacements can assume the role of compositional disorder in driving a spin-glass transition. |
| first_indexed | 2024-03-06T21:13:39Z |
| format | Journal article |
| id | oxford-uuid:3f06f9e5-5998-45f4-8ff2-c7c48b311a47 |
| institution | University of Oxford |
| last_indexed | 2024-03-06T21:13:39Z |
| publishDate | 2016 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | oxford-uuid:3f06f9e5-5998-45f4-8ff2-c7c48b311a472022-03-26T14:29:29ZOrbital dimer model for a spin-glass state in Y2Mo2O7Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:3f06f9e5-5998-45f4-8ff2-c7c48b311a47Symplectic Elements at OxfordAmerican Physical Society2016Thygesen, PPaddison, JZhang, RBeyer, KChapman, KPlayford, HTucker, MKeen, DHayward, MGoodwin, AThe formation of a spin glass generally requires that magnetic exchange interactions are both frustrated and disordered. Consequently, the origin of spin-glass behavior in Y2Mo2O7—in which magnetic Mo4þ ions occupy a frustrated pyrochlore lattice with minimal compositional disorder—has been a longstanding question. Here, we use neutron and x-ray pair-distribution function (PDF) analysis to develop a disorder model that resolves apparent incompatibilities between previously reported PDF, extended x-rayabsorption fine structure spectroscopy, and NMR studies, and provides a new and physical explanation of the exchange disorder responsible for spin-glass formation. We show that Mo4þ ions displace according to a local “two-in–two-out” rule on each Mo4 tetrahedron, driven by orbital dimerization of Jahn-Teller active Mo4þ ions. Long-range orbital order is prevented by the macroscopic degeneracy of dimer coverings permitted by the pyrochlore lattice. Cooperative O2− displacements yield a distribution of Mo–O–Mo angles, which in turn introduces disorder into magnetic interactions. Our study demonstrates experimentally how frustration of atomic displacements can assume the role of compositional disorder in driving a spin-glass transition. |
| spellingShingle | Thygesen, P Paddison, J Zhang, R Beyer, K Chapman, K Playford, H Tucker, M Keen, D Hayward, M Goodwin, A Orbital dimer model for a spin-glass state in Y2Mo2O7 |
| title | Orbital dimer model for a spin-glass state in Y2Mo2O7 |
| title_full | Orbital dimer model for a spin-glass state in Y2Mo2O7 |
| title_fullStr | Orbital dimer model for a spin-glass state in Y2Mo2O7 |
| title_full_unstemmed | Orbital dimer model for a spin-glass state in Y2Mo2O7 |
| title_short | Orbital dimer model for a spin-glass state in Y2Mo2O7 |
| title_sort | orbital dimer model for a spin glass state in y2mo2o7 |
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