Giant anisotropic magnetostriction in Pr0.5Sr0.5MnO3

We show that the polycrystalline perovskite antiferromagnet Pr0.5Sr0.5MnO3 exhibits a giant anisotropic magnetostriction (λt=1.5×10−3 at T=25 K and H=14.2 T) contrary to much smaller λt (<0.1×10−3) found in most other three-dimensional manganites. The value of λt decreases rapidly as the Néel temperature is approached from below, but an unusually high value of λt is also found below the ferromagnetic Curie temperature. We suggest that the magnetic-field-induced antiferromagnetic-to-ferromagnetic transition is accompanied by a structural transition from orthorhombic to tetragonal symmetry and attribute the giant anisotropic effect to the preferential growth of the orbital disordered tetragonal (ferromagnetic) domains along the field direction in the eg-dx2−y2 orbital ordered orthorhombic (antiferromagnetic) matrix.