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od 2020-09-20

Title: Electric-field-gradient tensor and boron site resolved 11B NMR in single-crystalline YB12

Source: Physical Review B - Condensed Matter and Materials Physics

Year : 2007

Abstract:

B11 NMR measurements on a single crystal of YB12 have been performed at room temperature at a frequency of 128.4 MHz. The electric-field-gradient (EFG) tensor components and the principal axes calculated previously by first-principles methods have been verified experimentally. Three magnetically different boron-atom groups in the B12 cluster were clearly observed for the crystal orientation used in this work. This distinction results from different EFG-tensor orientations with respect to magnetic field and not from different quadrupolar splittings (νQ) or asymmetry-parameter values (η). The magnetically different boron atoms have been identified through the calculated angle dependence of the satellite transitions (0°–360°). Very satisfactory agreement between the calculated and experimental angular dependencies of the EFG tensor has been obtained. Similarly, the quadrupolar splittings and asymmetry parameters agree very well with those previously determined from NMR measurements on a powder sample of YB12.
(C)2007 American Physical Society

DOI: 10.1103/PhysRevB.75.184102   (Pobrane:  2020-10-21)