Large positive magnetoresistance and high mobility in topological insulator candidate LaP

Abstract

We reported herein the single crystal growth and the comprehensive study of basic physical properties including electronic transport, magnetic, specific heat of topological insulator candidate LaP. Single crystal LaP of rock salt type structure was synthesized by Sn flux method. Under low temperature and high magnetic field of T= 2 K and B= 9 T, large positive magnetoresistance (LMR) of 500% was discovered. The Hall effect measurements show that the conduction carriers are dominated by holes among the temperature range from 300 K to 2 K, the carrier concentration n_{h} =4.94times 10^{19} cm−3 and n_{e} =5.02times 10^{16} cm−3 and the mobility of LaP reached as high as mu _{h}=1.57times 10^{4} cm2 V−1 S−1 and mu _{e} = 1.55times 10^{3} cm2 V−1 S−1 obtained at 2 K, which can be explained by multiband model physics like other topological quantum material systems with large MR. LaP shows diamagnetism over a wide temperature range from 2 K to 300 K without any magnetic phase transition by susceptibility measurements. No evidence of phase transitions from 2 K to 300 K was observed in the specific heat measurement. The electronic specific heat coefficient is obtained 0.538 m J mol−1 K−2 for LaP single crystal, which responds to a small electron density state near the Fermi level. Our results would be helpful in renewing interest in studying emergent phenomena arisen from topological semimetals. LaP offers a platform for understanding the interactions between large magnetoresistance, high mobility and topological band structure.