Enhancing the magnetoelectric coupling in YMnO3 by Ga doping

We study the magnetoelectric coupling in YMnO3 single crystal, in which a part of Mn3+ ions is substituted by nonmagnetic Ga3+ ions. While the antiferromagnetic ordering temperature is gradually suppressed by Ga doping, the magnetocapacitance is enhanced by two orders of magnitude, which we attribute to the lifting of frustration of interlayer spin interactions in doped samples. We also find that the dielectric constant anomaly below magnetic ordering temperature is strongly anisotropic, which we explain using a phenomenological Landau description of ferroelectric antiferromagnets.