Peculiarities of the volume magnetostriction of La1-xSrxMnO3 in the Curie point region

The parallel lambda (parallel to) and perpendicular lambda (perpendicular t o) magnetostriction (with respect to the applied magnetic field) and the th ermal expansion Deltal/l are studied on La1-xSrxMnO3 single crystals with x =0.1, 0.15, and 0.3. For the conducting sample with x=0.3 and the semicondu cting sample with x=0.15 the volume magnetostriction (omega=lambda (paralle l to)+2 lambda (perpendicular to)) is negative and the parallel to omega pa rallel to (T) curves go through a maximum at the Curie point T-C. At T >T-C its Deltal/l temperature dependence is stronger than linear. For the semic onducting sample with x=0.1, omega is negative at T <T-C and parallel to om ega parallel to -->0 at T similar toT(C). Its Deltal/l is linear at T great er than or equal toT(C). The behavior of omega and Deltal/l are explained b y a magnetic two-phase state, due to strong s-d exchange. (C) 2001 American Institute of Physics.