Anisotropy of Magnetoresistance Hysteresis around the $\nu =2\mathrm{/}3$ Quantum Hall State in Tilted Magnetic Field

We present an anisotropy of the hysteretic transport around the spin transition point at Landau level filling factor $\nu =2\mathrm{/}3$ in tilted magnetic field. When the direction of the in-plane component of the magnetic field $B_{\parallel }$ is normal to the probe current $I$, a strong hysteretic transport due to the current-induced nuclear spin polarization occurs. When $B_{\parallel }$ is parallel to $I$, on the other hand, the hysteresis almost disappears. We also demonstrate that the nuclear spin-lattice relaxation rate $T_1^{-1}$ at the transition point increases with decreasing angle between the directions of $B_{\parallel }$ and $I$. These results suggest that the morphology of electron spin domains around $\nu =2\mathrm{/}3$ is affected by the current direction.