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arXiv · 0811.3549

Thermodynamics of the frustrated ferromagnetic spin-1/2 Heisenberg chain

J. Richter·M. Härtel·D. Ihle·S. -L. Drechsler
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Abstract

We studied the thermodynamics of the one-dimensional J1-J2 spin-1/2 Heisenberg chain for ferromagnetic nearest-neighbor bonds J1 < 0 and frustrating antiferromagnetic next-nearest-neighbor bonds J1 > 0 using full diagonalization of finite rings and a second-order Green-function formalism. Thereby we focus on J2 < |J1|/4 where the ground state is still ferromagnetic, but the frustration influences the thermodynamic properties. We found that their critical indices are not changed by J2. The analysis of the low-temperature behavior of the susceptibility chi leads to the conclusion that this behavior changes from chi \propto T^{-2} at J2 < |J1|/4 to chi \propto T^{-3/2} at the quantum-critical point J2=|J1|/4. Another effect of the frustration is the appearance of an extra low-T maximum in the specific heat C_v(T) for J2 \gtrsim |J1|/8, indicating its strong influence on the low-energy spectrum.

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J. Richter, M. Härtel, D. Ihle, S. -L. Drechsler. 2008-11-21. Thermodynamics of the frustrated ferromagnetic spin-1/2 Heisenberg chain. https://doi.org/10.1088/1742-6596/145/1/012064

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