Linear magnetoresistance and structural distortion in layered SrCu_4–xP₂ single crystals

We report a systematic study on layered metal SrCu_4−xP₂ single crystals via transport, magnetization, thermodynamic measurements and structural characterization. We find that the crystals show large linear magnetoresistance without any sign of saturation with a magnetic field up to 30 T. We also observe a phase transition with significant anomalies in resistivity and heat capacity at T_p ∼ 140 K. Thermal expansion measurement reveals a subtle lattice parameter variation near T_p, i.e., ΔL_c/L_c ∼ 0.062%. The structural characterization confines that there is no structure transition below and above T_p. All these results suggest that the nonmagnetic transition of SrCu_4−xP₂ could be associated with structural distortion.