Se p 20 01 Magnetotransport Properties of Antiferromagnetic Y Ba 2 Cu 3 O 6 . 25 Single Crystals

In-plane ∆ρab/ρab and out-of-plane ∆ρc/ρc magnetoresistivities of antiferromagnetic Y Ba2Cu3O6.25 single crystals were measured in magnetic fields H applied along the ab plane. ∆ρab/ρab is a superposition of two components: The first component is strongly in-plane anisotropic, changing sign from negative when H ‖ I to positive when H ⊥ I. The second component is positive, quadratic in H, and isotropic in the ab-plane. ∆ρc/ρc displays a fourfold symmetry upon in-plane rotation of the magnetic field, with maxima along the easy axes of antiferromagnetic spin ordering and minima along unfavorable directions of spin orientation (45 from the Cu−O− Cu bonds).