A ug 2 00 9 Local magnetism and magnetoelectric effect in HoMnO 3 studied with muon-spin relaxation

We present the results of muon-spin relaxation (μSR) measurements on the hexagonal manganite HoMnO3. Features in the temperature-dependent relaxation rate λ correlate with the magnetic transitions at 76 K, 38 K and 34 K. The highest temperature transition, associated with the ordering of Mn moments has the largest effect on λ. The application of a static electric field of E = 10 Vm below T = 50 K causes a small reduction in λ which is suggestive of coupling between ferroelectric and magnetic domain walls in the ordered state of the material.