Eur. Phys. J. B 11, 377-383 (1999)
https://doi.org/10.1007/s100510050948

Heavy electron YbNi₂B₂C and giant exchange YbNiBC: ¹⁷⁰Yb Mössbauer spectroscopy and magnetization studies

¹ CEA, Centre d'Études de Saclay, Département de Recherche sur l'État Condensé, les Atomes et les Molécules, 91191 Gif-sur-Yvette Cedex, France
² Tata Institute of Fundamental Research, Bombay 40005, India
³ LCMTR-CNRS, Groupe des Laboratoires de Thiais, 2-8 rue Henri-Dunant, 94320 Thiais, France
⁴ LURE, Université Paris-Sud, 91405 Orsay Cedex, France

Received: 5 February 1999
Published online: 15 October 1999

Abstract

We report low temperature ¹⁷⁰Yb Mössbauer spectroscopy and magnetization measurements on two tetragonal non-superconducting quaternary borocarbides, YbNi₂B₂C and YbNiBC, and present L_III edge X-ray absorption data in YbNiBC. Both compounds show evidence of 4f-conduction band hybridisation. In the heavy electron YbNi₂B₂C, measurements down to 0.023 K show that only a small hyperfine interaction is present and we estimate an upper limit of 0.05-0.1 for any Yb moment. In YbNiBC, magnetic ordering is observed below 4.2 K, in agreement with previous specific heat measurements. The single ion easy magnetization axis lies along the axis but the ordered Yb moments lie in the basal (a, b) plane. Their (extrapolated) saturated value is unusually low (0.35 ). The Yb-Yb exchange interaction is very large and highly anisotropic with the dominant component lying in the basal plane. We also report ¹⁶⁶Er Mössbauer and specific heat data in the ferromagnet ErNiBC.