Theoretical prediction of multiferroicity in double perovskiteY2NiMnO6

Abstract

We put forward double perovskites of the R2NiMnO6 family (with R a rare-earth atom) as a new class of multiferroics on the basis of ab initio density functional calculations. We show that changing R from La to Y drives the ground-state from ferromagnetic to antiferromagnetic with ↑↑↓↓ spin patterns. This E * -type ordering breaks inversion symmetry and generates a ferroelectric polarization of few µC/cm 2 . By analyzing a model Hamiltonian we understand the microscopic origin of this transition and show that an external electric field can be used to tune the transition, thus allowing electrical control of the magnetization.PACS numbers: 71.45. Gm, 71.10.Ca, Materials with simultaneous magnetic and ferroelectric ordering -multiferroics -are attracting enormous scientific interest due to their potential for applications in memory and data storage devices [1,2]. Multiferroics with magnetically induced ferroelectric order are particularly interesting due to their strong magneto-electric coupling, which is required for an electric (magnetic) control of magnetic (electric) order parameter: a very desirable property from a technological point of view [3]. Therefore, the search for new multiferroics with the ferroelectric order driven by the magnetic order is currently a very active and important field of research.In this letter, we show, by using first-principles density functional theory (DFT) calculations and a model Hamiltonian analysis, that the magnetic order in the double perovskite compounds R 2 NiMnO 6 (RNMO) changes from ferromagnetic for R=La and Sm to the E * -type for R=Y. The E * -type magnetic structure consists of ↑-↑-↓-↓ spin chains along the cubic perovskite-like directions (see Fig. 3), or equivalently, zig-zag ferromagnetic (FM) spin-chains antiferromagentically coupled in-plane to the neighboring zig-zag chain, with an out-of-plane FM coupling [4]. E * -type magnetism breaks inversion symmetry and thus allows a ferroelectric polarization to occur. We will show that indeed Y 2 NiMnO 6 is multiferroic with a electric polarization of few µC/cm 2 . We will show that vice versa the magnetic transition from ferro to E * -type can be tuned by an external electric field, thus allowing electric control of the ferromagnetic order parameter.The double perovskite La 2 NiMnO 6 (LNMO) is a ferromagnetic insulator with a Curie temperature close to room temperature (T c ∼ 280 K). The structure of LNMO changes from rhombohedral (R3) at high temperature, to monoclinic with P2 1 /n symmetry group at low temperature [5,6]. DFT has been successful in understanding the ferromagnetic (FM) insulating behaviour and the dielectric anomalies observed experimentally in LNMO [7,8]. We work in the framework of density-functional theory, using the Vienna ab initio simulation package [9], in which the Kohn-Sham equations are computed using the projector augmented wave method (PAW) and solved describing electronic exchange and correlation in the generalized gradient approximation (PBE) [10,11].The spin resolved density of states (D...

Magnetic entropy change and critical exponents in double perovskite Y2NiMnO6

“…Electrical conduction has been described by polaron hopping mechanism [19]. In this communication, we identify substantial magnetocaloric characteristics in the multiferroic double perovskite Y 2 NiMnO 6 [17]. Further, towards a microscopic understanding of such uncommon effects, we study the critical phenomena near its second order ferromagnetic transition.…”

“…Specifically, the ground state magnetic order in R 2 NiMnO 6 (R=rare earth ion) is reportedly tuneable by changing the rare earth ion [17]. Theoretical works on Y 2 NiMnO 6 proposes it to be ferroelectric material with an intrinsic polarization in the E-type ferromagnetic ground state [17].…”

The ferroelectric polarization of Y2CoMnO6aligns along the b-axis: the first-principles calculations

“…21 On the other hand, Y2NiMnO6 was first predicted to have a ferroelectric ground state with the E-AFM structure on the ab-plane, and then a polarization about 0.0035 C/cm 2 was measured at low temperature. 22,23 It is noted that there are a number of oxides in this category where the B site may accommodate different magnetic ions. Recent experiments revealed the ferroelectricity of other double perovskites, e.g.…”

Magnetism driven ferroelectricity above liquid nitrogen temperature in Y2CoMnO6

“…[9][10][11][12][13][14] For example, a range of magnetic ordering and the consequent tuning of magneto-electric properties have been reported in ferromagnetic (La) to complex antiferromagnetic (Lu,Y) correlation with varying size of nontransition metal ion or rare earth ions. 20 Such magnetic orderings possess frustrated Ising spin chains with ↑↑-↓↓ spin pattern that are predicted to break the spatial inversion symmetry leading to the emergence of ferroelectricity. 14,20 Polycrystalline samples of Y 2 CoMnO 6 were synthesized by the solid state reaction method from the stoichiometric mixture of Y 2 O 3 , CoO and MnO 2 .…”

“…20 Such magnetic orderings possess frustrated Ising spin chains with ↑↑-↓↓ spin pattern that are predicted to break the spatial inversion symmetry leading to the emergence of ferroelectricity. 14,20 Polycrystalline samples of Y 2 CoMnO 6 were synthesized by the solid state reaction method from the stoichiometric mixture of Y 2 O 3 , CoO and MnO 2 . It was ground and pelletized under pressure of 5 ton.…”