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Spin-wave thermodynamics of square-lattice antiferromagnets revisited
| Title: | Spin-wave thermodynamics of square-lattice antiferromagnets revisited |
| Authors: | Yamamoto, Shoji Browse this author →KAKEN DB | | Noriki, Yusaku Browse this author |
| Issue Date: | 11-Mar-2019 |
| Journal Title: | Physical Review B |
| Volume: | 99 |
| Issue: | 9 |
| Start Page: | 94412 |
| Publisher DOI: | 10.1103/PhysRevB.99.094412 |
| Abstract: | Modifying the conventional spin-wave theory in a manner based on the Wick decomposition, we present an elaborate thermodynamics of square-lattice quantum antiferromagnets. Our scheme is no longer accompanied by the notorious problem of an artificial transition to the paramagnetic state inherent in modified spin waves in the Hartree-Fock approximation. In the cases of spin 1/2 and spin 1, various modified-spin-wave findings for the internal energy, specific heat, static uniform susceptibility, and dynamic structure factor are not only numerically compared with quantum Monte Carlo calculations and Lanczos exact diagonalizations but also analytically expanded into low-temperature series. Modified spin waves interacting via the Wick decomposition provide reliable thermodynamics over the whole temperature range of absolute zero to infinity. Adding higher-order spin couplings such as ring exchange interaction to the naivest Heisenberg Hamiltonian, we precisely reproduce inelastic-neutron-scattering measurements of the high-temperature-superconductor-parent antiferromagnet La2CuO4. Modifying Dyson-Maleev bosons combined with auxiliary pseudofermions also yields thermodynamics of square-lattice antiferromagnets free from thermal breakdown, but it is less precise unless temperature is sufficiently low. Applying all the schemes to layered antiferromagnets as well, we discuss the advantages and disadvantages of modified spin-wave and combined boson-pseudofermion representations. |
| Rights: | ©2019 American Physical Society |
| Type: | article |
| URI: | http://hdl.handle.net/2115/74901 |
| Appears in Collections: | 理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 山本 昌司
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