Hall effect in the extremely large magnetoresistance semimetal WTe2

Abstract

We systematically measured the Hall effect in the extremely large magnetoresistance semimetal WTe 2 . By carefully fitting the Hall resistivity to a two-band model, the temperature dependencies of the carrier density and mobility for both electron-and hole-type carriers were determined. We observed a sudden increase of the hole density below ∼160 K, which is likely associated with the temperature-induced Lifshitz transition reported by a previous photoemission study. In addition, a more pronounced reduction in electron density occurs below 50 K, giving rise to comparable electron and hole densities at low temperature. Our observations indicate a possible electronic structure change below 50 K, which might be the direct driving force of the electronhole "compensation" and the extremely large magnetoresistance as well. Numerical simulations imply that this material is unlikely to be a perfectly compensated system.

Hall effect within the colossal magnetoresistive semimetallic state ofMoTe2

“…Perfect carrier compensation was claimed 15 to be responsible for the magnetoresistivity of WTe 2 . This is partially supported by the geometry of the Fermi surface extracted from Shubnikov de Haas (SdH) quantum oscillations 24 , and by a two-band analysis of the Halleffect 25 . Nevertheless, the two-carrier analysis of the Hall-effect indicates that the fraction of holes is ∼ 0.9 times that of electrons, contradicting the claims of Ref.…”

“…Subsequently, we analyze the Hall response through the isotropic two-carrier model which was successfully used to describe the contributions of holes and electrons to the electrical transport properties of a number of compounds 25,[35][36][37][38] . In this model, the conductivity tensor, in its complex representation, is given by:…”

Anomalous magnetotransport properties of high-quality single crystals of Weyl semimetal WTe2: Sign change of Hall resistivity

“…To overcome this difficulty, we perform fitting combining eqs. (2) and (3) so that the model satisfies both of the ρyx(B) and ρ(B) data at the same time; this technique was not utilized in the previous studies [13][14][15]. In order to determine the parameters with a high level of confidence, the nonlinear behaviors in ρyx(B) is necessary.…”

“…Note that the field dependence of ρyx is strongly nonlinear, i.e., the Hall coefficient ρyx/B is not a field-independent constant. The nonlinear behavior becomes more prominent with decreasing temperature below ~20 K. Considering that WTe2 is an almost compensated semimetal, one simple model to explain the observed nonlinear field dependence of ρyx is the conventional two-band model [11][12][13][14][15]. In this model, the total conductivity tensor σ is the sum of electron and hole conductivity and is expressed in the complex representation,…”

“…Hall resistivity ρyx, which provides a complementary information on the charge carriers, can be analyzed based on the two-band model. There are three reports for the measurements and analyses of ρyx [13][14][15]. However, because the unique set of the solutions based on the two-band model is difficult to be obtained only using ρyx data, the characters of the two types of carriers have not been clarified yet.…”