Strong magnetoelastic effect on the magnetoelectric phenomena of TbMn ₂O₅

Comparative studies of magnetoelectric susceptibility (α), magnetization (M), and magnetostriction (u) in TbMn₂O₅ reveal that the increment of M owing to the field-induced Tb3⁺ spin alignment produces a field-asymmetric line shape in the α(H) curve, which is conspicuous in a low-temperature incommensurate phase but persistently subsists in the entire ferroelectric phase. Correlations among electric polarization, u, and M2 variation represent linear relationships, unambiguously showing the significant role of Tb magnetoelastic effects on the low-field magnetoelectric phenomena of TbMn₂O₅. An effective free energy capturing the observed experimental features is also suggested.