Origin of the turn-on temperature.pdf (1.3 MB)
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journal contribution
posted on 2016-04-29, 00:00 authored by YL Wang, LR Thoutam, ZL Xiao, J Hu, S Das, ZQ Mao, J Wei, R Divan, A Luican-Mayer, GW Crabtree, WK KwokA hallmark of materials with extremely large magnetoresistance (XMR) is the transformative turn-on temperature behavior: when the applied magnetic field H is above certain value, the resistivity versus
temperature ρ(T ) curve shows a minimum at a field dependent temperature T ∗, which has been interpreted
as a magnetic-field-driven metal-insulator transition or attributed to an electronic structure change. Here, we
demonstrate that ρ(T ) curves with turn-on behavior in the newly discovered XMR material WTe2 can be scaled
as MR ∼ (H/ρ0)
m with m ≈ 2 and ρ0 being the resistivity at zero field. We obtained experimentally and also
derived from the observed scaling the magnetic field dependence of the turn-on temperature T ∗ ∼ (H − Hc)
ν
with ν ≈ 1/2, which was earlier used as evidence for a predicted metal-insulator transition. The scaling also
leads to a simple quantitative expression for the resistivity ρ∗ ≈ 2ρ0 at the onset of the XMR behavior, which fits
the data remarkably well. These results exclude the possible existence of a magnetic-field-driven metal-insulator
transition or significant contribution of an electronic structure change to the low-temperature XMR in WTe2.
This work resolves the origin of the turn-on behavior observed in several XMR materials and also provides a
general route for a quantitative understanding of the temperature dependence of MR in both XMR and non-XMR
materials.