Muonium transitions in 4H silicon carbide

Preliminary low-field data on the diamagnetic muon spin rotation signal in 4H-SiC are presented. The initial results on all three electrical types of 4H-SiC are compared with those for the 6H polytype. Analysis of amplitude transitions at low temperatures in n- and p-type samples indicates carrier capture. At temperatures above 600 K, an increase in diamagnetic amplitude and an associated dip in the phase indicate a slowly formed state in the p-type material. We discuss possible identification of transitions evident from temperature dependent diamagnetic amplitudes and correlations with neutral muonium centers.