Thermodynamics of spin-1∕2antiferromagnet-antiferromagnet-ferromagnet and ferromagnet-ferromagnet-antiferromagnet trimerized quantum Heisenberg chains

Abstract

The magnetization process, the susceptibility and the specific heat of the spin-1/2 AF-AF-F and F-F-AF trimerized quantum Heisenberg chains have been investigated by means of the transfer matrix renormalization group (TMRG) technique as well as the modified spin-wave (MSW) theory. A magnetization plateau at m = 1/6 for both trimerized chains is observed at low temperature. The susceptibility and the specific heat show various behaviors for different ferromagnetic and antiferromagnetic interactions and in different magnetic fields. The TMRG results of susceptibility and the specific heat can be nicely fitted by a linear superposition of double two-level systems, where two fitting equations are proposed. Three branch excitations, one gapless excitation and two gapful excitations, for both systems are found within the MSW theory. It is observed that the MSW theory captures the main characteristics of the thermodynamic behaviors at low temperatures. The TMRG results are also compared with the possible experimental data.

Low-energy structure of the homometallic intertwining double-chain ferrimagnetsA3Cu3(PO4)4Yamamoto1, Ohara2 2007Phys. Rev. B186160View full textAdd to dashboardCite

“…A minimum of S͑0͒ as a function of temperature is characteristic of ferrimagnets. 6,7,18,25,30,[52][53][54] S͑0͒ monotonically decreases and increases with increasing temperature in ferromagnets and antiferromagnets, respectively.…”

Quantum Monte Carlo study of the spin-1/2 honeycomb Heisenberg model with mixed antiferromagnetic and ferromagnetic interactions in external magnetic fields

“…, resulting in that two modes of low-lying excitations cause two minimums [43,44] in C ν . The part of C ν contributed by lower frequency mode increases faster.…”

Magnetic properties of the spinS= 1/2 Heisenberg chain with hexamer modulation of exchange

“…The F-F-AF trimerized chain has been observed experimentally in the compound 3CuCl 2 .2dx [28]. During the recent years, the trimerized Heisenberg chains have been studied in details [29,30,31]. Using the density matrix renormalization group (DMRG) method, the observation of the plateaus for chains with different spin (S = 1/2, 1, 3/2, 2) has been reported [29].…”

“…Using the density matrix renormalization group (DMRG) method, the observation of the plateaus for chains with different spin (S = 1/2, 1, 3/2, 2) has been reported [29]. A magnetization plateau at m = 1/3 of the saturation value exists at low temperature for both, F-F-AF and AF-AF-F trimerized spin-1/2 chains [30]. The spin structure factors are also calculated for the trimerized cases and found that the static structure factor dose not vary with the external magnetic field at the plateau state [31].…”