Magnetoresistance anomalies in antiferromagnetic YBa2Cu3O6+x: Fingerprintsof charged stripes

We report novel features in the in-plane magnetoresistance (MR) of heavily underdoped YBa2Cu3O6+x, which unveil a developed "charged stripe" structure in this system. One of the striking features is an anisotropy of the MR wi th a "d-wave"-like symmetry upon rotating the magnetic field H within the a b plane, which is caused by the rotation of the stripes with the external f ield. With decreasing temperature, a hysteresis shows up below similar to 2 0 K in the MR curve as a function of H and finally below 10 K the magnetic- field application produces a persistent change in the resistivity. This "me mory effect" is caused by the freezing of the directionally ordered stripes .