posted on 2016-04-29, 00:00authored byYL Wang, LR Thoutam, ZL Xiao, J Hu, S Das, ZQ Mao, J Wei, R Divan, A Luican-Mayer, GW Crabtree, WK Kwok
A 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.
Funding
This work was supported by the U.S. Department of Energy,
Office of Science, Basic Energy Sciences, Materials Sciences
and Engineering Division. Use of the Center for Nanoscale
Materials, an Office of Science user facility, was supported
by the U.S. Department of Energy, Office of Science, Office
of Basic Energy Sciences, under Contract No. DE-AC02-
06CH11357. L.R.T. and Z.L.X. acknowledge NSF Grant No.
DMR-1407175. The work at Tulane University was supported
by the NSF under Grant DMR-1205469 and Louisiana Board
of Regents under Grant LEQSF(2014-15)-ENH-TR-24.