Dramatically decreased magnetoresistance in non-stoichiometric WTe(2) crystals

Recently, the layered semimetal WTe(2) has attracted renewed interest owing to the observation of a non-saturating and giant positive magnetoresistance (~10(5)%), which can be useful for magnetic memory and spintronic devices. However, the underlying mechanisms of the giant magnetoresistance are still under hot debate. Herein, we grew the stoichiometric and non-stoichiometric WTe(2) crystals to test the robustness of giant magnetoresistance. The stoichiometric WTe(2) crystals have magnetoresistance as large as 3100% at 2 K and 9-Tesla magnetic field. However, only 71% and 13% magnetoresistance in the most non-stoichiometry (WTe(1.80)) and the highest Mo isovalent substitution samples (W(0.7)Mo(0.3)Te(2)) are observed, respectively. Analysis of the magnetic-field dependent magnetoresistance of non-stoichiometric WTe(2) crystals substantiates that both the large electron-hole concentration asymmetry and decreased carrier mobility, induced by non-stoichiometry, synergistically lead to the decreased magnetoresistance. This work sheds more light on the origin of giant magnetoresistance observed in WTe(2).