Unveiling ferrimagnetic ground state, anomalous behavior of the exchange-bias field around spin reorientation, and magnetoelectric coupling in YbCr1−xFexO3 ( 0.1≤x≤0.6 )

Abstract

We present a comzrehensive experimental study of the magnetic structure, magnetic and dielectric properties of the rare-earth orthochromite-orthoferrite solid-solution series YbCr1−xFexO3 (0.1≤x≤0.6). Room-temperature synchrotron x-ray diffraction analysis reveals the absence of any superlattice reflections, which excludes the formation of a B-site-ordered double-perovskite-like phase and establishes the complete solid solubility of Fe at the Cr site within the framework of orthorhombic Pbnm structure. We demonstrate that canted antiferromagnetic ground state of YbCrO3 is converted to a ferrimagnetic with Fe doping, in addition to an increase in the magnetic ordering temperature. An unusual, second magnetic transition (first-order in nature) appears for x≥0.3 samples below the ferrimagnetic transition temperature (e.g., at 70 K for x=0.4), which is identified as the spin reorientation of transition metal ions from the neutron powder diffraction measurements, and primarily, driven by the f−d exchange interaction. A clear evidence of the anomalous behavior of coercivity and exchange bias field is found around the spin reorientation temperature, which is characterized by a significant change in the magnetocrystalline anisotropy due to spin reorientation of transition metal ions. Temperature-dependent dielectric data exhibit the magnetoelectric coupling as well as a ferroelectric relaxor-like state at the onset of ferrimagnetic ordering. Here, we reveal the anomalous behavior of the exchange bias field and significant magnetoelectric coupling around the spin reorientation and ferrimagnetic transitions, respectively, in YbCr1−xFexO3.