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Electronic structure of KTi(SO4)(2)center dot H2O: An S=1/2 frustrated chain antiferromagnet

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Kasinathan Deepa, Koepernik K., Janson O., Nilsen G. J., Piatek J. O., Ronnow H. M., Rosner H.,
Project Setup for studies of quantum phenomena in condensed matter systems at ultra-low temperatures in magnetic vector fields
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Original article (peer-reviewed)

Journal PHYSICAL REVIEW B
Volume (Issue) 88(22)
Page(s) 224410
Title of proceedings PHYSICAL REVIEW B
DOI 10.1103/physrevb.88.224410

Open Access

URL https://infoscience.epfl.ch/record/196123?ln=en
Type of Open Access Repository (Green Open Access)

Abstract

The compound KTi(SO4)(2)center dot H2O was recently reported as a quasi-one-dimensional spin-1/2 compound with competing antiferromagnetic nearest-neighbor exchange J(1) and next-nearest-neighbor exchange J(2) along the chain with a frustration ratio alpha = J(2)/J(1) approximate to 0.29 [G. J. Nilsen, H. M. Ronnow, A. M. Lauchli, F. P. A. Fabbiani, J. Sanchez-Benitez, K. V. Kamenev, and A. Harrison, Chem. Mater. 20, 8 (2008)]. Here, we report a microscopically based magnetic model for this compound derived from density functional theory (DFT) based electronic structure calculations along with respective tight-binding models. Our (LSDA+U-d) calculations confirm the quasi-one-dimensional nature of the system with antiferromagnetic J(1) and J(2), but suggest a significantly larger frustration ratio alpha(DFT) approximate to 0.94-1.4, depending on the choice of U-d and structural parameters. Based on transfer matrix renormalization group (TMRG) calculations we find alpha(TMRG) = 1.5. Due to an intrinsic symmetry of the J(1)-J(2) model, our larger frustration ratio alpha is also consistent with the previous thermodynamic data. To identify the frustration ratio alpha unambiguously, we propose performing high-field magnetization and low-temperature susceptibility measurements.
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