55Mn nuclear magnetic resonance study of high-pressure synthesized hexagonal DyMn2, TbMn2 and GdMn2

The ground state magnetic properties of high-pressure synthesized Laves phase compounds with the hexagonal C14 structure, DyMn₂, TbMn₂ and GdMn₂, were investigated by ⁵⁵Mn nuclear magnetic resonance technique and compared with those of the equilibrium phases with the cubic C15 structure. We observed two different signals in zero field for DyMn₂, which are just the same as those for the C15 phase, indicating the coexistence of magnetic and non-magnetic manganese sites. For TbMn₂, a zero-field spectrum with two peaks was observed in the frequency range below 80 MHz, suggesting that the manganese moment becomes unstable and that manganese atoms are partially non-magnetic, which is in contrast to large and stable magnetic moments in the C15 phase. For GdMn₂, a broad zero-field spectrum was observed just in the same frequency range as that of the C15 phase, indicating that all manganese atoms have stable large moments.