Hydrogen Bond Tuning of Magnetoelectric Coupling in Metal–Organic Frameworks

The ordering of hydrogen bonds plays a vital role in breaking space inversion symmetry and inducing the paraelectric to ferroelectric phase transition in metal–organic frameworks (MOFs). Magnetic field control of electric polarization has been observed in some MOFs. However, little is known about the effect of hydrogen bonds on the magnetoelectric effect in MOFs. Here, we studied the hydrogen bond tuning of the magnetoelectric effect in the hybrid inorganic–organic materials [(CH3)2NH2]­Mn­(HCOO)3 and [(CH3)2NH2]­Mn0.5Ni0.5(HCOO)3. Hydrogen bond energy is weakened by the substitution of Ni ions in [(CH3)2NH2]­Mn­(HCOO)3, revealed by the dielectric measurement and Raman spectra. Moreover, the hydrogen bond strength can tune the contributions of the electric polarization components from the DMA+ cation and HCOO– framework, inducing the positive and negative magnetoelectric coefficients in [(CH3)2NH2]­Mn­(HCOO)3 and [(CH3)2NH2]­Mn0.5Ni0.5(HCOO)3, respectively. Our study gives a microscopic mechanism for understanding the hydrogen bond assisted magnetoelectric effect.