Issue
EPL
Volume 88, Number 2, October 2009
Article Number 27001
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/88/27001
Published online 22 October 2009
EPL, 88 (2009) 27001
DOI: 10.1209/0295-5075/88/27001

Quantum electric dipole glass and frustrated magnetism near a critical point in Li2ZrCuO4

E. Vavilova1, 2, A. S. Moskvin3, 4, Y. C. Arango1, A. Sotnikov1, 5, S.-L. Drechsler3, R. Klingeler1, O. Volkova6, A. Vasiliev6, V. Kataev1 and B. Büchner1

1   Institute for Solid State Research, IFW Dresden - 01171 Dresden, Germany, EU
2   Zavoisky Physical-Technical Institute of RAS - 420029 Kazan, Russia
3   Institute for Theoretical Solid State Physics, IFW Dresden - 01171 Dresden, Germany, EU
4   Ural State University - 620083 Ekaterinburg, Russia
5   A. F. Ioffe Physical-Technical Institute of the RAS - 194021 St.-Petersburg, Russia
6   Moscow State University - 119992 Moscow, Russia

v.kataev@ifw-dresden.de

received on 16 September 2009; accepted in final form by G. A. Sawatzky on 8 October 2009; published October 2009
published online 22 October 2009

Abstract
We report a new peculiar effect of the interaction between a sublattice of frustrated quantum spin-1/2 chains and a sublattice of pseudospin-1/2 centers (quantum electric dipoles) uniquely co-existing in the complex oxide $\gamma$-Li2ZrCuO4 ($\equiv$ Li2CuZrO4). 7Li nuclear magnetic resonance, Cu2+ electron spin resonance and a complex dielectric constant data reveal that the sublattice of Li+-derived electric dipoles orders glass like at Tg $\simeq$ 70 K yielding a spin site nonequivalency in the CuO2 chains. We suggest that such a remarkable interplay between electrical and spin degrees of freedom might strongly influence the properties of the spiral spin state in Li2ZrCuO4 that is close to a quantum ferromagnetic critical point. In particular that strong quantum fluctuations and/or the glassy behavior of electric dipoles might renormalize the exchange integrals affecting this way the pitch angle of the spiral as well as be responsible for the missing multiferroicity present in other helicoidal magnets.

PACS
75.10.Pq - Spin chain models.
76.60.-k - Nuclear magnetic resonance and relaxation.
77.22.-d - Dielectric properties of solids and liquids.

© EPLA 2009