Behavior of magnetoelectric hysteresis and role of rare earth ions in multiferroicity in double perovskite Yb2CoMnO6

Abstract

Double-perovskite multiferroics have been investigated because alternating orders of magnetic ions act as distinct magnetic origins for ferroelectricity. In Yb2CoMnO6, the frustrated antiferromagnetic order emerging at TN = 52 K induces ferroelectric polarization perpendicular to the c axis through cooperative O2− shifts via the symmetric exchange striction. In our detailed measurements of the magnetoelectric properties of single-crystalline Yb2CoMnO6, we observe full ferromagnetic-like hysteresis loops that are strongly coupled to the dielectric constant and ferroelectric polarization at various temperatures below TN. Unlike Lu2CoMnO6 with non-magnetic Lu3+ ions, we suggest the emergence of additional ferroelectric polarization along the c axis below the ordering temperature of magnetic Yb3+ ions, TYb ≈ 20 K, based on the spin structure established from recent neutron diffraction experiments. While the proposed description for additional ferroelectricity, ascribed to the symmetric exchange striction between Yb3+ and Co2+/Mn4+ magnetic moments, is clearly given, anomalies of dielectric constants along the c axis are solely observed. Our interesting findings on magnetoelectric hysteresis and the possible development of additional ferroelectricity reveal notable characteristics of double perovskites and provide essential guidance for the further examination of magnetoelectric functional properties.

Magnetization, dielectric and thermal studies in the double perovskite polycrystalline compound Tm2CoMnO6

“…A clear anomaly is seen at around T = 60 K, which is matching with the T c obtained from our M (T ) data. There is an additional broad hump at low-T around 8 K that can be corroborated with the spin orientation of Tm-moments (T s ) as observed in our magnetization data as well as in other double perovskites reported in the literature [10,33,38]. The 50 kOe C p data have been found to differ [Fig.…”

“…Similar metamagnetic transitions have already been reported in case of other members of the series, namely, Er 2 CoMnO 6 , Tb 2 CoMnO 6 , Sm 2 CoMnO 6 . [10,19,27]. For the present TCMO sample, the metamagnetism shows some unusual characteristics.…”

“…(i) It is not present in the virgin leg [OA curve in fig. 3 It has been already mentioned that the magnetic interactions J T m−Co , J T m−M n < 0 (AFM), while J Co−M n > 0 (FM) [10,22,27]. The Tm presumably attains an ordered magnetic state below about 8 K (inset of fig.…”

“…From the last century, scientists have been ceaselessly exploring magnetic materials, especially magnetic oxides to find out various exotic functional properties and to utilize them in wide range of technological applications such as memory devices, medical techniques, energy storage, CFC-free refrigeration, remote sensing devices and many more [1][2][3][4][5][6]. Double perovskite (DP) oxides having general formula A 2 BB O 6 , comprising of magnetic ions are such a system where several unusual and interesting features like colossal magneto-resistance, multiferroicity [7][8][9][10], large magnetocaloric effect [11][12][13], spin phonon coupling [14], exchange bias [14][15][16], metamagnetism [17][18][19][20] have been reported. Particularly, DP manganites having rare earth (R) ions at A-site have been the focus of research as manganese offers stable mixed valency in some compounds leading to charge localization, phase separation, glassy behaviour etc.…”

“…From the neutron diffraction studies, it is evident that there are two types of spin orderings, namely, (i) Etype: characterized by up-up-down-down (↑↑↓↓) arrangements of Co 2+ and Mn 4+ spins along a particular crystallographic direction resulting competing nearest neighbour ferromagnetic(FM) and next-nearest neighbour antiferromagnetic (AFM) exchange interactions; and (ii) F-type: having Co 2+ and Mn 4+ spins in FM collinear arrangements [22][23][24][25][26]. RCMO with smaller size R-ions, such as Lu 2 CoMnO 6 , Y 2 CoMnO 6 , Yb 2 CoMnO 6 have Ephase and they show ferroelectricity that emerges perpendicular to the c-axis through the symmetric exchange striction [7,10,24]. For Yb 2 CoMnO 6 , on application of a magnetic field, E-type phase destabilizes to F-type through a metamagnetic jump.…”