Multiband effect in elastoresistance of Fe(Se,Te)

¹ Faculty of Physics, M.V. Lomonosov Moscow State University - Moscow 119991, Russia
² Institute of Experimental Mineralogy, RAS - Chernogolovka, 142432, Russia
³ Ural Federal University - Ekaterinburg, 620002, Russia
⁴ Institute of Geology and Petroleum Technologies, Kazan Federal University - Kazan, 420008, Russia
⁵ MSU Quantum Technology Centre - Moscow, 119991, Russia
⁶ Skobeltsyn Institute of Nuclear Physics - Moscow 119991, Russia
⁷ State University “Dubna” - Dubna, 141980, Russia
⁸ National University of Science and Technology “MISiS” - Moscow 119049, Russia

Received: 25 May 2020
Accepted: 18 August 2020

Abstract

We have investigated the elastoresistance of two Te_x () compounds that have a close chemical composition but differ significantly in electronic properties. The first compound has a negative temperature coefficient of resistance and does not show any phase transitions other than a superconducting one. The elastoresistance of this compound approximately follows the law which is a special case of the Curie-Weiss law, which is usually observed for Fe(Se,S) with metallic conductivity. The second compound has a metallic type of conductivity and, in addition to the superconducting transition, there is also a phase transition at a temperature of about 30 K. The elastoresistance of the second compound is sign-reversing and can be approximated with the sum of two Curie-Weiss–type terms with opposite signs and different critical temperatures. We attribute this behavior to the competition of contributions to the elastoresistance from different band valleys. These competing contributions may appear since the composition of our compound is close to the critical point at which the low-temperature ground state in the 11 series of iron-based superconductors changes from electronic nematic order to magnetic order.