Effect of epitaxial strain on the magneto-electric coupling of YMnO3 thin films

Abstract

We report synthesis of phase pure multiferroic YMnO 3 thin films on sapphire (0001) with conducting ZnGaO buffer contact layer. Films were prepared by using pulsed laser deposition technique and characterized using x-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive absorption spectroscopy (EDAX) and magnetic field dependent dielectric measurement techniques. Structural characterizations indicated phase purity and epitaxial nature of the films. The dielectric response indicated an anomaly in dielectric constant ε and tanδ in the vicinity of 30 K, well below the bulk Néel temperature ~ 70 K. This anomaly in ε (T) and tanδ and its magnetic field dependence is explained as an influence of strain due to lattice mismatch between the substrate and YMnO 3 film. A substantial enhancement in magnetocapacitance was also observed for magnetic field applied parallel to ab plane of the film. Our results show that it is possible to tune the multiferroic property of YMnO 3 via changes in ferroelastic route.2

Valence band structure of YMnO3 and the spin orbit coupling

“…Fig. 1(c) illustrates the temperature dependent magnetic behavior which clearly shows the anti-ferromagnetic transition temperature (T N ) at 70 K, which is well above the earlier reported value of T N (37 K) by Singh et al 15 in thin film form of h-YMnO 3. The observed T N is similar to that observed in bulk h-YMnO 3 , 4,5 indicating the high quality of the studied film.…”

“…The present work is on thin film form since thin films offer controlled way to synthesize multiferroic materials with the possibility of either modified ferroelectric properties or enhancement in magneto-electric/elastic coupling by manipulating the substrate induced strain, grain boundaries, and vacancies. [13][14][15][16][17] Among various techniques to grow thin films, pulsed laser deposition (PLD) technique has been successfully employed in the study of thin films of hexagonal YMnO 3 . 8,15-18 Though the report on core level study of sputtered films is available in the literature, 19 not much is known regarding the VBS of h-YMnO 3 thin film.…”

Magnetoelectric Response in Multiferroic SrFe12O19 Ceramics

“…The maximum relative change in ε (Δε(B)/ε(0) = [ε(B)-ε(0)]/ε(0), where B = 254mT) is 1174%, which reflects a giant magnetocapacitance effect of SrFe 12 O 19 ceramics. This magnetocapacitance order is much higher than that of YMnO 3 thin films with a magnitude of only 5.5% at 3T [46]. Thus, the hexaferrite with long-wavelength magnetic structures exhibits remarkable ME responses at low B fieldand roomtemperature, which opens substantial possibilities for applications of ME systems.…”

Dominance of magnetoelastic coupling in multiferroic hexagonalYMnO3

“…Several recent discoveries involving magnetism driven ferroelectricity and new insight into the intertwined states of electric, magnetic and elastic order parameters have redefined the broad scope of research in multiferroic materials. [1][2][3][4][5][6][7] Such multifunctional materials are of great technological significance; potentially it could lead to eight-state memory devices, 8 gate ferroelectrics based field-effect transistors, 9 and electric field controlled magnetic resonance devices. [10][11][12][13][14] Furthermore, because of the associated rich magnetic-electric-elastic phase diagram, new functionalities and their theoretical foundation are under intense investigation.…”