Structural Secrets of Multiferroic Interfaces

Abstract

We present an experimental and theoretical study of the geometric structure of ultrathin BaTiO(3) films grown on Fe(001). Surface x-ray diffraction reveals that the films are terminated by a BaO layer, while the TiO(2) layer is next to the top Fe layer. Cations in termination layers have incomplete oxygen shells inducing strong vertical relaxations. Onset of polarization is observed at a minimum thickness of two unit cells. Our findings are supported by first-principles calculations providing a quantitative insight into the multiferroic properties on the atomic scale.

Film size-dependent voltage-modulated magnetism in multiferroic heterostructures

“…Such complex interplay between the spin (magnetism), lattice (strain), charge (electrostatic) and orbit (e.g. charge-driven interfacial orbital hybridization [45][46][47][48][49][50] or reconstruction [51][52][53][54][55]) across the interface of the multiferroic heterostructure would be a very interesting but tough issue. -The mesoscale mechanism of such voltage-controlled magnetism in multiferroic heterostructures is also important.…”

On the superparamagnetic size limit of nanoparticles on a ferroelectric substrate

“…The density of these nanoparticles is chosen as low enough such that inter-nanoparticle couplings can be ignored. For this system it has been shown theoretically [27,28,29] and demonstrated experimentally [30,31] that the magnetoelectric coupling originating from the spin-polarized screening charges at the FE/FM interface [33] is large and stable even at room temperature [28]. In view of the already realized experiment [32] it is well conceivable that the suggested system in Fig.…”

Helical multiferroics for electric field controlled quantum information processing

“…This allows us to steer, for instance, magnetic order with moderate electric fields opening thus the door for magnetoelectric spintronics and spin-based information processing with ultra low power consumption and dissipation [10,[23][24][25]. These prospects are fueled by advances in synthesis and nanofabrication which renders feasible versatile MF nano-and quantum structures with enhanced multiferroic coupling [2][3][4][5][6]31]. From a fundamental point of view MF are also fascinating as their properties often emerge from an interplay of competing exchange and electronic correlation, crystal symmetry, and coupled spin-charge dynamics.…”

“…Intrinsic coupling between the order parameters, e.g., ferromagnetism (FM), ferroelectricity (FE), and/or ferroelasticity (for an overview we refer to Refs. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]), allows for multifunctionality of devices with qualitatively new conceptions [10,[22][23][24][25]. Particulary advantageous is the high sensitivity of some MF compounds to external fields [26][27][28][29][30].…”