Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session J33: Focus Session: Dielectric, Ferroelectric, and Piezoelectric Oxides: Multiferroics & Magnetoelectrics II |
Hide Abstracts |
Sponsoring Units: DMP DCOMP Chair: Craig Fennie, Cornell University Room: C143/149 |
Tuesday, March 22, 2011 11:15AM - 11:27AM |
J33.00001: Correlation between magnetocapacitance effect and polarization flop direction in a slanted magnetic field in Tb$_{1-x}$Dy$_{x}$MnO$_{3}$ Nobuyuki Abe, Hajime Sagayama, Hiroshi Umetsu, Taka-hisa Arima, Kouji Taniguchi Recent extensive studies show that the cycloidal spin system can possess electric polarization through the spin-orbit coupling. The magnetoelectric coupling in multiferroics is enhanced by the clamping of helimagnetic and ferroelectric domain walls. For example, DyMnO$_{3}$ shows a gigantic magnetocapacitance effect caused by the microscopic motion of multiferroic domain walls at a magnetic field induced \textbf{\textit{P}}-flop transition. In contrast, the enhancement of capacitance at the \textbf{\textit{P}}-flop transition is much smaller in TbMnO$_{3}$. Here, we show the systematic control of magnetocapacitance effect in helimagetic ferroelectric Tb$_{1-x}$Dy$_{x}$MnO$_{3}$ as a function of the composition ratio $x$ and the intensity of the applied magnetic field. It has been also found that the rotation direction of \textbf{\textit{P}} in a slanted magnetic field changes with $x$ and $H$. The crossover between small and large enhancement in magnetocapacitance corresponds to the switch in the \textbf{\textit{P}}-flop direction. The correlation can be explained by assuming the mobility of domain wall would be dominated by the thickness of domain walls in a helical magnet. [Preview Abstract] |
Tuesday, March 22, 2011 11:27AM - 11:39AM |
J33.00002: Giant Magnetoelectric Effect in Antiferromagnetic BaMnO$_{3-\delta}$ and Its Derivatives M. Ge, O.B. Korneta, T.F. Qi, S. Parkin, L.E. DeLong, G. Cao, P. Schlottmann Hexagonal perovskite 15R-BaMnO$_{2.99}$ with a ratio of cubic to hexagonal layers of 1/5 in the unit cell is an antiferromagnetic insulator that orders at a N\'eel temperature T$_{N }$= 220 K. Here we report structural, magnetic, dielectric and thermal properties of single crystal BaMnO$_{2.99}$ and its derivatives BaMn$_{0.97}$Li$_{0.03}$O$_{3}$ and Ba$_{0.97}$K$_{0.03}$MnO$_{3}$. The central findings of this work are: \textbf{(1)} these materials possess a usually large, high-temperature magnetoelectric effect that amplifies the dielectric constant by more than an order of magnitude near their respective N\'eel temperature; \textbf{(2)} Li and K doping can readily vary the ratio of cubic to hexagonal layers and cause drastic changes in dielectric and magnetic properties. These findings provide a new paradigm for developing \textit{novel}, \textit{high-temperature magnetoelectric} \textit{materials} that may eventually contribute to technology. [Preview Abstract] |
Tuesday, March 22, 2011 11:39AM - 11:51AM |
J33.00003: Electric-field control of magnetic orderings in the tetragonal BiFeO$_{3}$ Chun-Gang Duan We present a systematic first-principles study on the magnetic properties of the tetragonal BiFeO$_{3}$ (P4mm) with various in-plane lattice constants. The Heisenberg model is applied to study the behaviors of exchange constants (J$_{1a}$, J$_{1c}$, J$_{2a}$, J$_{2c})$ under the influence of the in-plane strain. We find that in certain region of the in-plane lattice constant, switching the direction of polarization from out of plane to in-plane by electric field could result in transition of magnetic orderings, e.g., from G-type to C-type antiferromagnetic states in tetragonal BiFeO$_{3}$. This may open a new avenue to controlling magnetoresistance using electric field. [Preview Abstract] |
Tuesday, March 22, 2011 11:51AM - 12:27PM |
J33.00004: Ferroelectric polarization in the magnetic world Invited Speaker: Switchable spontaneous polarization in ferroelectrics is produced by a structural distortion of a high-symmetry reference phase which lowers the symmetry to a polar space group. Under certain conditions, this structural distortion and symmetry breaking can also induce ferromagnetism and other changes, such as a metal-insulator transition, allowing the possibility of electric and magnetic field control. In this talk, I will present first-principles illustrations of specific materials realizations of the rich variety of this behavior in magnetic perovskite oxides, identified using a database of first-principles calculations of the full phonon dispersions of a range of magnetic perovskites, including the d3 compounds SrMnO3and SrCaO3, the d5 compounds BiFeO3, and the series SrMO3 (M= V, Cr, Mn, Fe, Co). First, I will discuss an epitaxial-strain-induced multiferroic phase produced by large spin-phonon coupling in SrMnO3 [1]. Then, I will turn to colossal magnetoresistance based on a ferromagnetic- metal/antiferromagnetic-ferroelectric phase boundary with epitaxial strain in SrCoO3, which exhibits typical ferromagnetic metallic character in room-temperature but with a large spin-phonon coupling by which antiferromagnetic ordering favors a polar distortion. Lastly, I will discuss the identification of perovskite superlattice systems in which the symmetry lowering produced layer-by-layer ordering produces a phase with ferroelectrically-induced weak ferromagnetism. I will present first-principles calculations demonstrating these behaviors in BaMnO3/SrMnO3 superlattices and other systems which could provide robust experimental realizations. \\[4pt] [1] J. H. Lee and K. M. Rabe, ``Epitaxial-strain-induced multiferroicity in SrMnO3 from first principles,'' Phys. Rev. Lett. 104, 207204 (2010) [Preview Abstract] |
Tuesday, March 22, 2011 12:27PM - 12:39PM |
J33.00005: Magnetic and multiferroic phases of single-crystalline Mn$_{1-x}$Co$_{x}$WO$_{4}$ K.-C. Liang, R.P. Chaudhury, Y.-Q. Wang, Y.Y. Sun, B. Lorenz, F. Ye, J.A. Fernandez-Baca, H.A. Mook, C.W. Chu The recent interest of MnWO$_{4}$ system is due to the strong correlation between the long-wavelength magnetic structure and the ferroelectric polarization. To understand the effects of Co substitutions on magnetic and multiferroic phases of MnWO$_{4}$, we studied the magnetic and dielectric properties of the single-crystalline Mn$_{1-x}$Co$_{x}$WO$_{4}$ compounds. At lower Co substitution, the commensurate (CM) AF1 phase was found suppressed but could be restored in external magnetic fields along b axis. We also observed the ferroelectric polarization along b axis suppressed by a b-axis magnetic field. On the other hand, the higher Co substitution such as 15{\%} showed more complex magnetic phases, which warrants future investigation. With Neutron scattering data, more detailed magnetic orders of the various phases would be revealed, and the relationship between magnetic phases and ferroelectric polarization will be discussed. [Preview Abstract] |
Tuesday, March 22, 2011 12:39PM - 12:51PM |
J33.00006: Magnetoelectricity in BiFeO$_3$ films - first-principles-based computations and phenomenology Sergey Prosandeev, Igor Kornev, Laurent Bellaiche A first-principles-based effective Hamiltonian is used to compute linear and quadratic magnetoelectric (ME) coefficients in epitaxial (001) BiFeO$_3$ thin films. Its predictions are analyzed within a phenomenological model that provides analytical expressions of the ME coefficients in terms of polarization, as well as, dielectric and magnetic susceptibilities. Main discoveries are: (i) the quadratic ME coefficient is dramatically enhanced by increasing the magnitude of the compressive strain within the Cc phase, as similar to the previously reported enhancement of the linear ME coefficient in these films; (ii) the enhancements of the linear and quadratic ME coefficients have the same macroscopic origin, namely an increase in the dielectric permittivity; and (iii) the relative contribution of {\it two} different free-energy terms on the total linear ME coefficient is extracted from the simulations. The analytical expressions also help in understanding other ME effects. [Preview Abstract] |
Tuesday, March 22, 2011 12:51PM - 1:03PM |
J33.00007: First Principles Study on Magnetoelectric Effects in Ba$_2$CoGe$_2$O$_7$ Kunihiko Yamauchi, Silvia Picozzi Magnetoelectric (ME) effects, or magnetically-induced ferroelectricity, are attracting large interests due to promising applications for novel type of devices. While the microscopic origin of ME effects is mostly classified as relate to spin current and/or exchange striction, a novel mechanism originating in spin- dependent $p$-$d$ hybridization has been proposed and well explained ME effects observed in antiferromagnetic Ba$_2$CoGe$_2$O$_7$. In this study, we theoretically confirmed the magnetically induced electric polarization, whose size is dependent on the direction of Co spins. By means of both Landau theory and density functional calculations, the behavior of the experimentally observed polarization was well reproduced. Microscopically, we suggest single-site spin orbit coupling to slightly change the Co-$d$ orbital shape upon changing the direction of Co spins, resulting in ``asymmetric" $p$-$d$ hybridization and consequent change in the electric polarization. [Preview Abstract] |
Tuesday, March 22, 2011 1:03PM - 1:15PM |
J33.00008: Magnetoelectric resonance in S=3/2 two-dimensional antiferromagnet Ba$_{2}$CoGe$_{2}$O$_{7}$ Shin Miyahara, Nobuo Furukawa We have investigated dynamical magnetoelectric effects in S = 3/2 two-dimensional antiferromagnet Ba$_{2}$CoGe$_{2}$O$_{7}$. It is a quasi two-dimensional antiferromagnet. Below T$_{N}$ = 6.7 K, the Co magnetic moments show an antiferromagnetic ordering [1]. Recently, the material is paid attention to due to the magnetic field induced ferroelectric polarization [2,3]. Such multiferroics behaviors can be explained well by considering a spin-dependent metal-ligand hybridization mechanism on a Heisenberg model with strong uniaxial anisotropy term [3,4]. Through the spin dependent polarization, electric component of light can modulate the spin structures. As a result, electric component of light can excite magnetic excitations. We can clarify selection rules and resonance peak positions in absorption. When both magnetic and electric components induce the same magnetic excitation, cross correlated term, where electric component induced excitation is deduced to the ground state by magnetic component and vice versa, is realized. The effects of such cross correlation can be observed directly as linear directional dichroism in absorption process.[1] A. Zheludev \textit{et al.}, Phys. Rev. B \textbf{68 }024428 (2003). [2] H.T. Yi \textit{et al}., Appl. Phys. Lett. \textbf{92 }212904 (2008). [3] H. Murakawa et al., Phys. Rev. Lett. \textbf{105} 137202 (2010). [4] T. Arima, J. Phys. Soc. Jpn. \textbf{76} 073702 (2007). [Preview Abstract] |
Tuesday, March 22, 2011 1:15PM - 1:27PM |
J33.00009: Investigation of Multiferroic properties of the Co doping SrBi$_{2}$Nb$_{2}$O$_{9}$ William Perez, Nora Ortega, Ashok Kumar, Ram Katiyar Multiferroics (MF) are novel class of next generation multifunctional materials, however there are very few single-phase MF materials existing in nature. Thin films (TF) of (Sr$_{x}$Co$_{1-x})$Bi$_{2}$Nb$_{2}$O$_{9}$ (SCBN) with x = 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3 with thickness $\sim $400 nm were fabricated from individual SCBN targets on Pt/Ti/SiO$_{2}$/Si substrate by pulsed laser deposition technique. The x-ray diffraction studies revealed orthorhombic structure of SCBN for up to 20{\%} Co doped TF without any phase segregation, the splitting in (200) peak was observed above 25{\%} of Co doping. The room temperature (RT) Raman spectra of SCBN TF showed SrBi$_{2}$Nb$_{2}$O$_{9 }$ peaks in all compositions, however additional modes appeared in the 600-800 cm$^{-1 }$frequency region. The dielectric constant of all SCBN films showed linear frequency dispersion above 1 kHz, and their values are in the range of 400 to 650 at 1 kHz. An increase in tangent loss from $\sim $ 0.040 to 0.135 at 1 kHz was observed with increase in Co concentration. All SCBN TF show well defined hysteresis loop with remanent polarization of about 16 $\mu $C/cm$^{2}$. However, less saturation in the ferroelectric loop was observed with increase of Co content. Both magnetic and magneto-electric behavior of TF along with the ferroelectric properties will be discussed. [Preview Abstract] |
Tuesday, March 22, 2011 1:27PM - 1:39PM |
J33.00010: Large crystal-symmetry-induced magnetoelectric coupling in the quadruple perovskite BiMn$_3$Mn$_4$O$_{12}$ A. Gauzzi, G. Rousse, F. Mezzadri, G. Calestani, G. Andre, F. Bouree, M. Calicchio, E. Gilioli, R. Cabassi, F. Bolzoni, A. Prodi, P. Bordet, M. Marezio The remarkable properties of manganese oxides $A$MnO$_3$ with perovskite structure, such as the colossal magnetoresistance and the multiferroicity, arise from peculiar charge, spin and orbital orderings of the Mn \textit{e$_g$} electrons driven by cooperative Jahn-Teller distortions of the MnO$_6$ octahedra. Mastering these orderings remains a challenge owing to local structural distortions and electronic inhomogeneities enhanced by chemical substitutions and oxygen defects. We show that these difficulties are absent in \textit{quadruple} perovskites $A$Mn$_3$Mn$_4$O$_{12}$. These compounds share with \textit{simple} perovskites $A$MnO$_3$ a similar pseudo-cubic network of corner-sharing MnO$_6$ octahedra and similar electronic properties associated with the Mn$^{3+}$ and Mn$^{4+}$ ions. However, they display smaller distortions thanks to the higher crystal symmetry an no defects. For $A$=Bi, by means of neutron powder diffraction we give direct crystallographic evidence of a large coupling between the electric dipole of the 6s lone pair of Bi$^{3+}$ and the magnetic structure of the Mn$^{3+}$ ions, which provides a hint for enhancing the magnetoelectric coupling in proper ferroelectrics in view of multiferroic applications. [Preview Abstract] |
Tuesday, March 22, 2011 1:39PM - 1:51PM |
J33.00011: Micorscopic theory of temperature-dependent magnetoelectric effect in Cr$_{2}$O$_{3}$ Andrea Scaramucci, Maxim Mostovoy, Nicola A. Spaldin, Kris T. Delaney We study the temperature dependence of the magnetoelectric effect in Cr$_{2}$O$_{3}$ by considering the coupling between electric polarization and spins induced by Heisenberg exchange interactions. The form of the coupling is obtained by symmetry analysis and its strength is calculated by {\it ab initio} methods. Using Monte Carlo simulations, we evaluate the temperature dependence of the largest component of the magnetoelectric susceptibility. The quantitative agreement of our results with experimental measurements shows that the dominant contribution to the linear magnetoelectric effect originates from nonrelativistic exchange interactions and spin fluctuations. The approach used can be applied to study other magnetoelectrics with collinear spin ordering and opens a new route for the design of materials with large magnetoelectric effect at high temperatures. [Preview Abstract] |
Tuesday, March 22, 2011 1:51PM - 2:03PM |
J33.00012: Pressure- and field-dependent Raman studies of magnetodielectric behavior in Mn$_{3}$O$_{4}$ M. Kim, S. Yuan, S.L. Cooper We present simultaneous pressure- and field-dependent Raman scattering studies of the magnetodielectric spinel, Mn$_{3}$O$_{4}$, which allow us to investigate both the microscopic origins and pressure dependence of magnetodielectric phenomena in this material. We identify the specific phonon modes responsible for the dramatic magnetodielectric behavior observed in this material, and show that these modes provide quantitative information regarding magnetodielectric behavior in Mn$_{3}$O$_{4}$ via the Lyddane-Sachs-Teller (LST) relationship. We also show that pressure can induce monoclinic distortions accompanied with magnetic ordering in Mn$_{3}$O$_{4}$. Finally, by exploring the field-dependent phonon spectrum at different pressures, we are able to map out the pressure-field structural phase diagram of Mn$_{3}$O$_{4}$ and explore the pressure-dependence of magnetodielectric behavior in this material. [Preview Abstract] |
Tuesday, March 22, 2011 2:03PM - 2:15PM |
J33.00013: Infrared optical properties of multiferroic FeTe$_{2}$O$_{5}$Br single crystal Kevin H. Miller, C. Martin, X. Xi, H. Berger, G.L. Carr, D.B. Tanner Reflection as a function of temperature has been measured on a single crystal of the anisotropic multiferroic FeTe$_{2}$O$_{5}$Br utilizing light spanning the far infrared to the visible portions of the electromagnetic spectrum. The complex dielectric function and optical properties along all three principal dielectric axes were obtained via Kramers-Kronig analysis and by fits to a Drude-Lorentz model. Transmission in the terahertz region as a function of temperature and magnetic field is also described, with particular focus on temperatures around the $\sim $10 K transition to the multiferroic state. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700