Magnetodielectric coupling of a polar organic-inorganic hybrid Cr(II) phosphonate.

Cr[(H3N-(CH2)2-PO3)(Cl)(H2O)] represents a rare example of a polar organic-inorganic hybrid material that exhibits a canted antiferromagnetic order below TN=5.5 K. The unusual coexistence of a polar crystal structure and magnetic order triggered our investigation of the magnetodielectric coupling. The coupling is evidenced by an anomaly in the temperature dependence of the dielectric constant epsilon below the Néel temperature. The magnetocapacitance is enhanced by one order of magnitude below TN. The main characteristics of the magnetodielectic response are interpreted by Landau theoretical coupling terms.