Hybridization, superexchange, and competing magnetoelastic interactions in TiOBr

Roberto Macovez, Javier Luzon, Joachim Schiessling, Aymeric Sadoc, Lisbeth Kjeldgaard, Sander van Smaalen, Daniele Fausti, Paul H. M. van Loosdrecht, Ria Broer, and Petra Rudolf
Phys. Rev. B 76, 205111 – Published 20 November 2007

Abstract

A crystalline sample of TiOBr is probed at room temperature by a combination of electron spectroscopies and the results are compared to theoretical embedded-cluster calculations. Resonant photoemission of the valence band confirms that the lowest binding energy feature arises from the singly occupied Ti3d orbital. The polarization dependence of this orbital in nonresonant photoemission is consistent with the expected dominant dy2z2 character. The analysis of the TiL2,3 x-ray absorption spectra confirms the complete splitting of the Ti3d shell. X-ray absorption and resonant photoemission at the O1s edge provide direct evidence for hybridization between the transition metal orbitals and the O2p levels, which leads to superexchange interactions between the Ti ions. The existence of a mixing of O and Ti states and of strong superexchange interactions is supported by calculations of the ground-state electronic and magnetic properties. The calculated superexchange interchain interaction is one fifth in strength of the total magnetic coupling along the chain, and is antiferromagnetic in character. This O-mediated interchain interaction is frustrated in the room temperature phase of TiOBr and thus couples strongly to distortions of the soft lattice. The competition between the interchain magnetoelastic coupling and the spin-Peierls interaction might be at the origin of the complex TiOX phase diagram.

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  • Received 23 June 2007

DOI:https://doi.org/10.1103/PhysRevB.76.205111

©2007 American Physical Society

Authors & Affiliations

Roberto Macovez1, Javier Luzon1, Joachim Schiessling2, Aymeric Sadoc1, Lisbeth Kjeldgaard3, Sander van Smaalen4, Daniele Fausti1, Paul H. M. van Loosdrecht1, Ria Broer1, and Petra Rudolf1

  • 1Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747AG Groningen, The Netherlands
  • 2Department of Physics, Uppsala University, Box 530, SE-75121 Uppsala, Sweden
  • 3Max-lab, University of Lund, Box 118, SE-22100 Lund, Sweden
  • 4Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth, Germany

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Issue

Vol. 76, Iss. 20 — 15 November 2007

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