Ultrasonic study of the Nd0.5Sr0.5MnO3 manganite

Abstract The resistivity, ac susceptibility and ultrasonic sound velocities have been measured for the single-phase Nd 0.5 Sr 0.5 MnO 3 bulk sample. With decreasing temperature both the transverse and longitudinal ultrasonic sound velocities show two large stiffening stages just below the ferromagnetic transition temperature T C and the charge ordering transition temperature T CO , respectively. The sound velocity stiffening below T C was interpreted in terms of a significant decrease of the static Jahn–Teller distortion of the MnO 6 octahedra due to the spin-lattice coupling, whereas the dramatic sound velocity stiffening below T CO was attributed to the formation of coherent static Jahn–Teller distortion of the MnO 6 octahedra associated with the charge ordering. In an applied magnetic field of 0.5 T, the stiffening of the sound velocity near T CO shifts noticeably to a lower temperature.