Site Split of Antiferromagnetic α-Mn Revealed by ⁵⁵Mn Nuclear Magnetic Resonance

The magnetic structure of antiferromagnetic $\alpha$-Mn has been unclarified for almost 70 years since its magnetism was discovered. We measured the zero-field nuclear resonance spectra to obtain further insight into below $T_{\text{N}} = 95$ K. site II split two sites with five subpeaks owing quadrupole interaction, and this shows that ordered moments at are slightly tilted from $[001]$ direction. III revealed splits four $T_{\text{N}}$. These findings clearly demonstrate symmetry is lower than previously considered.