Publications
Vibrational properties and magnetic specific heat of the covalent chain antiferromagnet RbFeSe2
A. G. Kiiamov, Y. Lysogorskiy, F. G. Vagizov, L. R. Tagirov, D. A. Tayurskii, Z. Seidov, H.-A. Krug von Nidda, V. Tsurkan, D. Croitori, A. Günther, F. Mayr, A. Loidl.
Physical Review B, 98, 214411, (2018)
Abstract
The magnetic specific heat of RbFeSe2 and the spin state of Fe3+ ions in the compound have been studied.
Phonon dispersion and phonon density of states (PDOS), element specific and total, were evaluated from firstprinciples
calculations. It is shown that iron atoms in quasi-one-dimensional chains have dramatically different
vibrational properties against Rb and Se atoms: the Fe PDOS is mostly concentrated within two Einstein-like
optical phonon peaks at high frequencies. Analysis of our Mössbauer data for RbFeSe2, utilizing the calculated
Fe PDOS as well as our optical absorption measurements, have shown full agreement with the location of the
high-frequency optical-type lattice vibrations within the FeSe4 tetrahedra. The calculated PDOS was utilized
to evaluate the lattice contribution to the specific heat. The phonon heat capacity has been used to evaluate
the magnetic specific heat of the quasi-one-dimensional antiferromagnetically correlated Fe3+ ion chains in
RbFeSe2. An intermediate spin state S = 3/2 has been found most closely relevant to our magnetic entropy
analysis for Fe3+ ions in RbFeSe2.
Cite as: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.98.214411
DOI: 10.1103/PhysRevB.98.214411
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