Magnetic structure and exchange interactions in the Heisenberg pyrochlore antiferromagnet Gd₂Pt₂O₇

Journal article

The Heisenberg pyrochlore antiferromagnet Gd₂Pt₂O₇ is one of a series of gadolinium pyrochlore compounds with a variety of B-site cations. Despite the expected simplicity of a spin-only Gd³⁺ Heisenberg interaction model, the gadolinium pyrochlore series exhibits various complex magnetic ground states at low temperature. Gd₂Pt₂O₇ displays the highest temperature magnetic order of the series with TN=1.6 K, which has been attributed to enhanced superexchange pathways facilitated by empty 5deg Pt orbitals. In this study, we use various neutron scattering techniques on an isotopically enriched polycrystalline ¹⁶⁰Gd₂Pt₂O₇ sample to examine the magnetic structure and spin-wave excitation spectrum below TN in order to extract the dominant exchange interactions. We find that the ground-state magnetic structure is the Palmer-Chalker state previously seen in Gd₂Pt₂O₇ with an associated gapped excitation spectrum consistent with enhanced exchange interactions between further near-neighbor Gd3+ ions. We confirm this exchange model with analysis of the magnetic diffuse scattering in the paramagnetic regime using polarized neutrons.

Authors: Welch, PG; Paddison, JAM; Le, MD; Gardner, JS; Chen, W-T

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review B
• Volume: 105
• Issue: 9
• Article number: 94402
• Publication date: 2022-03-01
• Acceptance date: 2022-02-16
• DOI: 10.1103/physrevb.105.094402
• EISSN: 2469-9969
• ISSN: 2469-9950
• Language: English
• Keywords: FFR