Eur. Phys. J. B 34, 421-428 (2003)
https://doi.org/10.1140/epjb/e2003-00240-2

Electrical resistivity of the Ti₄O₇ Magneli phase under high pressure

¹ Laboratorio de Bajas Temperaturas, Departamento de Física, FCEyN, Universidad de Buenos Aires, Pabellón I, Ciudad Universitaria, 1428 Buenos Aires, Argentina
² CRTBT, CNRS, BP166, 38042 Grenoble Cedex 09, France
³ Facultad de Ciencias Experimentales y Técnicas, Universidad San Pablo, 28668 Boadilla del Monte, Spain
⁴ Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain

Corresponding author: ^a acha@df.uba.ar

Received: 11 February 2003
Revised: 19 June 2003
Published online: 9 September 2003

Abstract

We have measured resistivity as a function of temperature and pressure of Ti₄O₇ twinned crystals using different contact configurations. Pressures over 4 kbar depress the localization of bipolarons and allow the study of the electrical conduction of the bipolaronic phase down to low temperatures. For pressures P>40 kbar the bipolaron formation transition is suppressed and a nearly pressure independent behavior is obtained for the resistivity. We observed an anisotropic conduction. When current is injected parallel to the principal axis, a metallic conduction with interacting carrier effects is predominant. A superconducting state was not obtained down to 1.2 K, although evidences of the proximity of a quantum critical point were noticed. While when current is injected non-parallel to the crystal's principal axis, we obtained a logarithmic divergence of the resistivity at low temperatures. For this case, our results for the high pressure regime can be interpreted in the framework of interacting carriers (polarons or bipolarons) scattered by Two Level Systems.