Structural phase transitions and sound velocity anomalies in La(1-x)Sr(x)MnO3

The sound velocities dependencies on temperature V(T) were measured by means of resonance method have on the thin plates of quasimonocrystalline manganites La(1-x)Sr(x)MnO3. Results are presented for x=0.1, 0.125, 0.15, 0.175 and 0.2 in the temperature range from 70 to 350K. The V(T) behavior correlates with those of susceptibilities and magnetic moment M(T). For x=0.175 and 0.2 the transition to ferromagnetic state is accompanied by appearance of large but smooth rise in V(T) whereas structural phase transition between the rhomboedral ® and orthorhombic (O) structures is accompanied by sharp increase up to 15-20% in V(T). For x=0.1, 0.125 and 0.15 the structural phase transition between Jahn-Teller distorted orthorhombic structure (O’) and pseudocubic one (O’') is accompanied by deep minimum (~20-30%) in V(T).