Abstract:
We show that the polycrystalline perovskite antiferromagnet Pr0.5Sr0.5MnO3 exhibits a giant anisotropic magnetostriction (lambda(t)=1.5x10(-3) at T=25 K and H=14.2 T) contrary to much smaller lambda(t) (<0.1x10(-3)) found in most other three-dimensional manganites. The value of lambda(t) decreases rapidly as the Neel temperature is approached from below, but an unusually high value of lambda(t) 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 e(g)-d(x)(2)-y(2) orbital ordered orthorhombic (antiferromagnetic) matrix. (C) 2003 American Institute of Physics.
