Effects of in-plane magnetic field direction on the nuclear-spin relaxation in the image quantum Hall state

We investigated effects of the direction of in-plane magnetic field B∥ on the phase transition in the quantum Hall ferromagnet at Landau-level filling factor View the MathML source by the nuclear-spin relaxation measurements. We controlled the angle φ between the direction of B∥ and a current I; when B∥ is parallel (perpendicular) to I, φ=0∘(φ=90∘). We found that the nuclear spin relaxation rate View the MathML source at φ=0∘ is about twice as much as that at φ=90∘. We discuss the anisotropic behavior of View the MathML source in term of a suppression of low-frequency electron spin fluctuations by B∥ at φ=90∘.