Hexagonal Manganites—(RMnO₃): Class (I) Multiferroics with Strong Coupling of Magnetism and Ferroelectricity

Figure 24

Magnetostriction of the 𝑐-axis of HoMnO₃ in longitudinal magnetic fields, 𝐻_𝑐. Note that different curves are vertically offset for better clarity. (a) High-temperature range. The vertical dashed lines mark the two phase transitions from 𝑃6₃𝑐𝑚 to 𝑃6₃ and to 𝑃6₃𝑐𝑚. (b) Low-temperature range. The inset to (b) shows the derivative at 3 K which clearly reveals 4 successive phase transitions.

(a)

(b)