Peculiarities of the electro- and magnetoresistivity of WTe2 and MoTe2 single crystals before and after quenching.

WTe₂ and MoTe₂ single crystals were grown, some of them were quenched, and the following properties were studied: electroresistivity in the temperature range from 1.8 to 300 K, magnetoresistivity at temperatures from 1.8 to 300 K in magnetic fields of up to 9 T. On the one hand, quenching leads to dramatic changes in the behaviour and value of the electroresistivity of MoTe₂; the type of the electroresistivity changes from "semiconductor" to "metallic", and the electroresistivity values of MoTe₂ before and after quenching differ by 8 orders of magnitude (!) at low temperatures. On the other hand, quenching is shown not to lead to significant changes in the behaviour and value of the electroresistivity of WTe₂. A relatively small increase in the electroresistivity of quenched WTe₂ at low temperatures can be associated with the scattering of current carriers by structural defects. The magnetoresistivity of MoTe₂ increases from 7 to 16% in a field of 9 T at a temperature of 12 K as a result of quenching. The magnetoresistivity of WTe₂ is shown to reach ∼1700% in a field of 9 T at 2 K. The behaviour of the magnetoresistivity of non-quenched samples is typical for compensated conductors with a closed Fermi surface. [ABSTRACT FROM AUTHOR]