Dresden 2014 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MA: Fachverband Magnetismus
MA 55: Poster II
MA 55.48: Poster
Freitag, 4. April 2014, 10:30–13:30, P2
10th 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 — •J. Richter1, A. Lohmann1, and H.-J. Schmidt2 — 1University Magdeburg, Germany — 2University Osnabrueck, Germany
We present the high-temperature expansion (HTE) up to 10th order of the specific heat C and the uniform susceptibility χ for Heisenberg models with arbitrary exchange patterns and arbitrary spin quantum number s. We encode the algorithm in a C++ program available at http://www.uni-magdeburg.de/jschulen/HTE/ which allows to get explicitly the HTE series for concrete Heisenberg models. We apply our algorithm to pyrochlore and kagome magnets. For the pyrochlore FM we use the HTE to estimate the Curie temperature Tc as a function of the spin quantum number s. We find that Tc is smaller than that for the simple cubic lattice, although both lattices have the same coordination number. For the kagome AFM the influence of the spin quantum number s on χ as a function of renormalized temperature T/s(s+1) is rather weak for temperatures down to T/s(s+1) ∼ 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.
[1] H.-J. Schmidt, A. Lohmann, and J. Richter, Phys. Rev. B 84, 104443 (2011). [2] A. Lohmann, H.-J. Schmidt, and J. Richter, arXiv:1309.0940.