26 November 2001 Physics Letters A 291 (2001) 34–38 www.elsevier.com/locate/pla On mechanisms of single-pulse echo formation in multidomain magnetic materials A.M. Akhalkatsi a , G.I. Mamniashvili b,∗ , S. Ben-Ezra c a Tbilisi State University, 3 Chavchavadze av., GE-380026, Tbilisi, Georgia b Institute of Physics, Academy of Sciences of Georgia, 6 Tamarashvili str., GE-380077, Tbilisi, Georgia c Physics and Engineering Research Institute at Ruppin, Emek Hefer, 40250, Israel Received 27 February 2001; received in revised form 14 August 2001; accepted 11 October 2001 Communicated by A. Lagendijk Abstract Results of comparative study of single-pulse and two-pulse echo responses and their secondary signals in lithium ferrite speak in favor of the effectiveness of multipulse formation mechanism of the single-pulse echo and its secondary signals as well as the secondary signals of two-pulse echo. The general source for their formation is the inequilibrity of spin system at the end of a cycle of the radiofrequency pulse train in this material.  2001 Elsevier Science B.V. All rights reserved. PACS: 76.60.Lz Keywords: NMR; Magnetics; Single-pulse echo; Secondary echo The single-pulse (SP) echo is a resonance response of the inhomogeneously broadened nuclear spin sys- tem to the application of a solitary radiofrequency (RF) pulse arising at a time, which is approximately equal to the pulse length τ after its termination. Though the SP echo was discovered by Bloom in 1955 for protons in water placed in an inhomogeneous mag- netic field, the mechanism for SP echo formation is not yet so clear-cut as for the classical two-pulse (TP) Hahn echo [1]. The SP echo formation mechanisms could be sub- divided into the following two classes: the first class concerns so-called edge-type mechanisms when edges of the RF pulse act similar two resonance RF pulses, * Corresponding author. E-mail address: gmamniashvili@yahoo.com (G.I. Mamniashvili). and the second class is the mechanisms of intrinsic na- ture of the SP echo formation [1]. The important role of the RF pulse edges for the edge mechanisms is due to the fact that just at these time moments the change of direction of the effective magnetic field H eff in the rotating coordinate system (RCS) is taking place. Such changes of H eff direction would arise in the case of nonresonance mechanism, fundamentally, from off-resonance effects, when the RF carrier frequency of the ideal RF pulse is detuned from the center frequency by an amount comparable to, or greater then the inhomogeneous line width. Besides, a similar effect would also take place for the distorsion mechanism for a pulse with distorted edges, which necessary arise in the cause of RF pulse generation, due to the nonideal properties of electronic circuitry’s components [1,2]. In both these cases the deviation angle of H eff from the equilibrium direction of nuclear magnetization 0375-9601/01/$ – see front matter  2001 Elsevier Science B.V. All rights reserved. PII:S0375-9601(01)00698-3