Magnetotransport of Sm2Ir2O7 across the pressure-induced quantum-critical phase boundary
Abstract Rare-earth pyrochlore iridates host two interlocking magnetic sublattices of corner-sharing tetrahedra and can harbour a unique combination of frustrated moments, exotic excitations and highly correlated electrons. They are also the first systems predicted to display both topological Weyl s...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2024-02-01
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| Series: | npj Quantum Materials |
| Online Access: | https://doi.org/10.1038/s41535-024-00624-8 |
| _version_ | 1797275983043100672 |
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| author | M. J. Coak K. Götze T. Northam De La Fuente C. Castelnovo J. P. Tidey J. Singleton A. T. Boothroyd D. Prabhakaran P. A. Goddard |
| author_facet | M. J. Coak K. Götze T. Northam De La Fuente C. Castelnovo J. P. Tidey J. Singleton A. T. Boothroyd D. Prabhakaran P. A. Goddard |
| author_sort | M. J. Coak |
| collection | DOAJ |
| description | Abstract Rare-earth pyrochlore iridates host two interlocking magnetic sublattices of corner-sharing tetrahedra and can harbour a unique combination of frustrated moments, exotic excitations and highly correlated electrons. They are also the first systems predicted to display both topological Weyl semimetal and axion insulator phases. We have measured the transport and magnetotransport properties of single-crystal Sm2Ir2O7 up to and beyond the pressure-induced quantum critical point for all-in-all-out (AIAO) Ir order at p c = 63 kbar previously identified by resonant X-ray scattering and close to which Weyl semimetallic behavior has been previously predicted. Our findings overturn the accepted expectation that the suppression of AIAO order should lead to metallic conduction persisting down to zero temperature. Instead, the resistivity-minimum temperature, which tracks the decrease in the AIAO ordering temperature for pressures up to 30 kbar, begins to increase under further application of pressure, pointing to the presence of a second as-yet unidentified mechanism leading to non-metallic behavior. The magnetotransport does track the suppression of Ir magnetism, however, with a strong hysteresis observed only within the AIAO phase boundary, similar to that found for Ho2Ir2O7 and attributed to plastic deformation of Ir domains. Around p c we find the emergence of a new type of electronic phase, characterized by a negative magnetoresistance with small hysteresis at the lowest temperatures, and hysteresis-free positive magnetoresistance above approximately 5 K. The temperature dependence of our low-temperature transport data are found to be best described by a model consistent with a Weyl semimetal across the entire pressure range. |
| first_indexed | 2024-03-07T15:21:52Z |
| format | Article |
| id | doaj.art-5e2a30f0ec264773b85ef146678383fc |
| institution | Directory Open Access Journal |
| issn | 2397-4648 |
| language | English |
| last_indexed | 2024-03-07T15:21:52Z |
| publishDate | 2024-02-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | npj Quantum Materials |
| spelling | doaj.art-5e2a30f0ec264773b85ef146678383fc2024-03-05T17:36:08ZengNature Portfolionpj Quantum Materials2397-46482024-02-019111210.1038/s41535-024-00624-8Magnetotransport of Sm2Ir2O7 across the pressure-induced quantum-critical phase boundaryM. J. Coak0K. Götze1T. Northam De La Fuente2C. Castelnovo3J. P. Tidey4J. Singleton5A. T. Boothroyd6D. Prabhakaran7P. A. Goddard8Department of Physics, University of WarwickDepartment of Physics, University of WarwickDepartment of Physics, Royal Holloway, University of LondonCavendish Laboratory, University of CambridgeDepartment of Chemistry, University of WarwickNational High Magnetic Field Laboratory, Los Alamos National LaboratoryDepartment of Physics, University of Oxford, Clarendon LaboratoryDepartment of Physics, University of Oxford, Clarendon LaboratoryDepartment of Physics, University of WarwickAbstract Rare-earth pyrochlore iridates host two interlocking magnetic sublattices of corner-sharing tetrahedra and can harbour a unique combination of frustrated moments, exotic excitations and highly correlated electrons. They are also the first systems predicted to display both topological Weyl semimetal and axion insulator phases. We have measured the transport and magnetotransport properties of single-crystal Sm2Ir2O7 up to and beyond the pressure-induced quantum critical point for all-in-all-out (AIAO) Ir order at p c = 63 kbar previously identified by resonant X-ray scattering and close to which Weyl semimetallic behavior has been previously predicted. Our findings overturn the accepted expectation that the suppression of AIAO order should lead to metallic conduction persisting down to zero temperature. Instead, the resistivity-minimum temperature, which tracks the decrease in the AIAO ordering temperature for pressures up to 30 kbar, begins to increase under further application of pressure, pointing to the presence of a second as-yet unidentified mechanism leading to non-metallic behavior. The magnetotransport does track the suppression of Ir magnetism, however, with a strong hysteresis observed only within the AIAO phase boundary, similar to that found for Ho2Ir2O7 and attributed to plastic deformation of Ir domains. Around p c we find the emergence of a new type of electronic phase, characterized by a negative magnetoresistance with small hysteresis at the lowest temperatures, and hysteresis-free positive magnetoresistance above approximately 5 K. The temperature dependence of our low-temperature transport data are found to be best described by a model consistent with a Weyl semimetal across the entire pressure range.https://doi.org/10.1038/s41535-024-00624-8 |
| spellingShingle | M. J. Coak K. Götze T. Northam De La Fuente C. Castelnovo J. P. Tidey J. Singleton A. T. Boothroyd D. Prabhakaran P. A. Goddard Magnetotransport of Sm2Ir2O7 across the pressure-induced quantum-critical phase boundary npj Quantum Materials |
| title | Magnetotransport of Sm2Ir2O7 across the pressure-induced quantum-critical phase boundary |
| title_full | Magnetotransport of Sm2Ir2O7 across the pressure-induced quantum-critical phase boundary |
| title_fullStr | Magnetotransport of Sm2Ir2O7 across the pressure-induced quantum-critical phase boundary |
| title_full_unstemmed | Magnetotransport of Sm2Ir2O7 across the pressure-induced quantum-critical phase boundary |
| title_short | Magnetotransport of Sm2Ir2O7 across the pressure-induced quantum-critical phase boundary |
| title_sort | magnetotransport of sm2ir2o7 across the pressure induced quantum critical phase boundary |
| url | https://doi.org/10.1038/s41535-024-00624-8 |
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