SURFACE MAGNETIZATION OF APERIODIC ISING QUANTUM CHAINS

We study the surface magnetization of aperiodic Ising quantum chains. Using fermion techniques, exact results are obtained in the critical r egion for quasiperiodic sequences generated through an irrational numb er as well as for the automatic binary Thue-Morse sequence and its gen eralizations modulo p. The surface magnetization exponent keeps its Is ing value, beta(s)=1/2, for all the sequences studied. The critical am plitude of the surface magnetization depends on the strength of the mo dulation and also on the starting point of the chain along the aperiod ic sequence.