Pb(TiO)Cu4(PO4)4, a recently found tetragonal antiferromagnet consisting of inversion asymmetric Cu4O12 square cupolas, is known to exhibit various magnetoelectric (ME) responses in a broad range of magnetic fields applied along the crystallographic  axis. Here, we report distinct ME responses in Pb(TiO)Cu4(PO4)4 subjected to high magnetic fields up to 18 T applied along different high-symmetric axes, namely, the a axis (Ba) and the c axis (Bc). For Ba, it is observed that a finite electric polarization emerges in a field-induced phase, whose sign is independent of the electric field cooling procedure. For Bc, while no electric polarization appears, the dielectric constant shows a sharp peak divergent toward the transition from a paramagnetic to a field-induced phase. We discuss the origin of the observed ME responses in terms of the ME activity of cluster multipole moments.
ASJC Scopus subject areas
- Physics and Astronomy(all)