High-Field Phase Diagram Of The Heavy-Fermion Metal Cein3: Pulsed-Field Nmr Study On Single Crystals Up To 56 T

The heavy-fermion antiferromagnet CeIn3 exhibits a field-induced anomaly associated with Fermi surface reconstruction at H* similar to 45 T, well below the antiferromagnetic (AFM) critical field that exceeds 60 T. In order to explore the origin of this anomaly, we have measured In-115 NMR spectra in pulsed magnetic fields up to 56 T using high-quality single crystals. To within experimental resolution, we do not detect any change in the NMR spectra that could suggest a modification in either the character of the hyperfine field or the electric field gradient at In sites through H*. This strongly suggests that the 45 T anomaly cannot be simply ascribed to a field-induced change in the magnetic structure of the AFM state. Neither do we find any evidence of changes in the crystallographic structure or in the distribution of charge density at H*. The field dependence of the NMR shift implies the existence of a field-induced anomaly in the hyperfine coupling above H*.