Extremely large magnetoresistance and non-trivial band topology in YSb semimetal

Abstract

The topologically protected states in a material lead to the occurrence of spectacular properties like massless fermions, high carrier mobility, extremely large magnetoresistance (XMR) and nontrivial Berry phase. In this context, we report the experimental realization of non-trivial band topology and nonsaturating XMR at low temperatures in a rock-salt type rare-earth monopnictide YSb semimetal which is ∼ two million percent at 2 K and 9 T. The Hall resistivity and Shubnikov-de Hass (SdH) oscillations confirm the multiband character of YSb crystal along with high carrier mobility. The analysis of SdH oscillations reveal a π-Berry phase for the α-band, indicating the non-trivial band topology in YSb. This non-trivial band topology is further confirmed by the observation of the topologically protected state, which is demonstrated by a high transport lifetime (τtr) to the quantum lifetime (τq) ratio, r = τtrτq = 300 times. The topological protection results in a very low zero-field resistivity at low temperatures. Here, we show that the topological protection mechanism, charge compensation and high carrier mobility are the key factors for obtaining XMR in YSb crystal.