Tenth-order high-temperature expansion for the susceptibility and the specific heat of spin-s Heisenberg models with arbitrary exchange patterns: Application to pyrochlore and kagome magnets

Autor(en): Lohmann, Andre
Schmidt, Heinz-Juergen
Richter, Johannes
Stichwörter: ANTIFERROMAGNET; EXCITATIONS; FLUCTUATIONS; LATTICE; Materials Science; Materials Science, Multidisciplinary; ORDER; Physics; Physics, Applied; Physics, Condensed Matter; SERIES; STATE; SYSTEM
Erscheinungsdatum: 2014
Volumen: 89
Ausgabe: 1
We present the high-temperature expansion (HTE) up to tenth order of the specific heat C and the uniform susceptibility chi for Heisenberg models with arbitrary exchange patterns and arbitrary spin quantum number s. We encode the algorithm in a C++ program provided in the Supplemental Material [http://link.aps.org/supplemental/10.1103/PhysRevB.89.014415] which allows to explicitly get the HTE series for concrete Heisenberg models. We apply our algorithm to pyrochlore ferromagnets and kagome antiferromagnets using several Pade approximants for the HTE series. For the pyrochlore ferromagnet, we use the HTE data for chi to estimate the Curie temperature T-c as a function of the spin quantum number s. We find that T-c is smaller than that for the simple-cubic lattice, although both lattices have the same coordination number. For the kagome antiferromagnet, the influence of the spin quantum number s on the susceptibility as a function of renormalized temperature T/s(s 1) is rather weak for temperatures down to T/s(s 1) similar to 0.3. On the other hand, the specific heat as a function of T/s(s 1) noticeably depends on s. The characteristic maximum in C(T) is monotonously shifted to lower values of T/s(s 1) when increasing s.
ISSN: 24699950
DOI: 10.1103/PhysRevB.89.014415

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