Magnetoresistance and magnetostriction effects in bulk Dy-doped La2/3Sr1/3MnO3

Colossal magnetoresistance and large magnetostriction effects of bulk polycrystalline manganites (La1−xDyx)2/3Sr1/3MnO3 (x=0–0.4x=0–0.4) have been investigated in a magnetic field up to 50 kOe and in the temperature range 10–380 K. By increasing the dysprosium content xx, the phase structure transits from a rhombohedral to an orthorhombic form at x∼0.3x∼0.3 due to the reduction of the average ionic radius of the A site 〈rA〉〈rA〉, which results in not only the rapid decrease of Curie temperature and the enhancement of resistivity and magnetoresistance effect, but also the antiferromagnetic behavior at low temperature. Near the Curie temperature, the volume magnetostriction (VMS) of x=0.3x=0.3 sample reaches a maximal value about −243×10−6 in a magnetic field of 50 kOe. The large VMS effects can be attributed to the structural transition from an orthorhombic to a rhombohedral phase and the presence of a magnetic two-phase ferromagnetic-antiferromagnetic state.