Charge density wave and excitonic magnetic polarons in CeTe2

Mechanisms of anomalous magnetic and transport properties in CeTe2 observed recently on single-crystal samples are studied by comparing with the nonma gnetic reference material LaTe2, as well as other typical low carrier-densi ty systems such as Ce monopnictides, doped Eu chalcogenides and Yb4As3.The present system is unique on the point of low-carrier semimetal due to CDW o f near perfect nesting, which is shown to be nearly independent of the spin -orbit splitting. The large residual resistivity indicates the giant molecu lar scattering due to excitonic states forming the distorted Wigner crystal , similar to Yb4As3. At low temperatures, induced magnetic polarons cause u nusual novel transport properties with a sharp peak of resistivity without any anomaly on other physical properties. This is attributed to a sharp gla ssy transition from an antiferromagnetic short-range ordering to the ferrom agnetic ordering of the magnetic polarons within each CeTe double layer san dwiching the mono Te layer. It is shown that, similar to Ce monopnictides, the j(z) = +/- 3/2 type strong nonlinear p-f mixing is the origin of the ma in anomalous magnetic properties. Lattice polarons are essential for the st able excitonic states in LaXc(2), as well as in CeTe2 in the ferromagnetic state. (C) 2000 Elsevier Science B.V. All rights reserved.