Magneto transport properties of antiferromagnetic YBa2Cu3O6.25 single crystals

In-plane Delta rho (ab)/rho (ab) and out-of-plane Delta rho (c)/rho (c) mag netoresistivities of antiferromagnetic YBa2Cu3O6.25 single crystals were me asured in magnetic fields H applied along the ab-plane. Delta rho (ab)/rho (ab) is a superposition of two components: The first component is strongly in-plane anisotropic, changing sign from negative when H parallel toI to po sitive when H perpendicular toI. The second component is positive, quadrati c in H, and isotropic in the ab-plane. Delta rho (c)/rho (c) displays a fou rfold symmetry upon in-plane rotation of the magnetic field, with maxima al ong the easy axes of antiferromagnetic spin ordering and minima along unfav orable directions of spin orientation (45 degrees from the Cu-O-Cu bonds). (C) 2001 Elsevier Science B.V. All rights reserved.