Optical evidence for a magnetically driven structural transition in the spin webG. Caimi1, L. Degiorgi1, H. Berger2 and L. Forró2
1 Laboratorium für Festkörperphysik, ETH Zürich - CH-8093 Zürich, Switzerland
2 Institut de Physique de la Matière Complexe (IPMC), EPF Lausanne CH-1015 Lausanne, Switzerland
received 30 November 2005; accepted in final form 9 June 2006
published online 30 June 2006
Cu3TeO6 is a modest frustrated S=1/2 spin system, which undergoes an antiferromagnetic transition at K. The antiferromagnetic spin alignment in Cu3TeO6 below TN is supposed to induce a magneto-elastic strain of the lattice. The complete absorption spectrum of Cu3TeO6 is obtained through Kramers-Kronig transformation of the optical reflectivity, measured from the far-infrared up to the ultraviolet spectral range as a function of temperature (T). Below K, we find a new mode at 208 cm-1. The spectral weight associated to this additional mode increases as with decreasing T below T*. The implication of the optical findings will be discussed in relation to the magnetic phase transition at TN.
78.20.-e - Optical properties of bulk materials and thin films.
75.50.Ee - Antiferromagnetics.
75.30.Gw - Magnetic anisotropy.
© EDP Sciences 2006