Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session L34: Focus Session: Interfaces in Complex Oxides - Heterointerfaces |
Hide Abstracts |
Sponsoring Units: DMP Chair: Jak Tchakhalian, Univeristy of Arkansas Room: C141 |
Tuesday, March 22, 2011 2:30PM - 2:42PM |
L34.00001: Electronic instabilities at paraelectric and superconducting interface: A mean field approach J.T. Haraldsen, A.V. Balatsky We examine the modified electronic states at the interface between superconducting and ferro(para)-electric films. We find that the coupling of a classical fluctuating paraelectric $P$ and superconducting $\psi$ order parameters can significantly modify these orders at the interface. Using a Ginzburg-Landau formalism, we show that linear and quadratic terms of the electric polarization produce instabilities in $\psi$ at the interface, where the linear interaction produces a modulation of the order parameters and create an interface-induced ferroelectric polarization within the paraelectric bulk state. We will discuss implications of this work for the experiments on the epitaxial oxide films. [Preview Abstract] |
Tuesday, March 22, 2011 2:42PM - 2:54PM |
L34.00002: Effect of Cu magnetism on superconductivity at YBa$_{2}$Cu$_{3}$O$_{7}$ / La$_{0.7}$Ca$_{0.3}$MnO$_{3 }$ interfaces J. Tornos, C. Visani, J. Garcia-Barriocanal, C. Leon, N.M. Nemes, J. Santamaria, M. Garcia-Hernandez, Yaohua Liu, A. Hoffmann, S.G.E. te Velthuis, J. Freeland, M. Varela, S.J. Pennycook The induced magnetism at the Cu edge of cuprate manganites interfaces has been proposed to depend on interface termination. We have prepared YBa$_{2}$Cu$_{3}$O$_{7}$ / La$_{0.7}$Ca$_{0.3}$MnO$_{3 }$trilayers showing Cu magnetism at both cuprate interfaces as evidenced from an XMCD experiment. This result results from the same termination occurring at both interfaces. The effect of Cu magnetism on superconductivity depression proposed by J. Salafrance and S. Okamoto is discussed. [Preview Abstract] |
Tuesday, March 22, 2011 2:54PM - 3:06PM |
L34.00003: Quantum Phase Transitions in Ultrathin YBCO/LCMO Superlattices Benjamin Gray, M. Kareev, E.J. Moon, J. Liu, I-C. Tung, M.J. Bedzyk, M. Veenendaal, J.W. Freeland, J. Chakhalian The rational design of complex oxide heterostructures enables the investigation of novel materials with antagonistic order parameters. Our previous work has provided insight into the role of orbital reconstruction and covalent bonding at the interface of such heterostructures. In this talk, we will further address the intriguing interfacial properties and possible coupling between layers in superlattices composed of alternating superconductive YBa2Cu3O7-x and ferromagnetic La2/3Ca1/3MnO3 layers upon approaching the ultra-thin limit. [Preview Abstract] |
Tuesday, March 22, 2011 3:06PM - 3:18PM |
L34.00004: Unconventional proximity effect and inverse spin-switch behavior in a model manganite/cuprate/manganite trilayer system Juan Salafranca, Satoshi Okamoto The proximity effect in a model manganite/cuprate system is investigated theoretically. We consider a situation in which spin-polarized electrons in manganite layers antiferromagnetically couple with electrons in cuprate layers as observed experimentally. The effect of the interfacial magnetic coupling is found to be much stronger than the injection of spin-polarized electrons into the cuprate region. As a result, the superconducting transition temperature depends on the thickness of cuprate layer significantly. Since the magnetic coupling creates {\em anti}-spin-polarization, an applied magnetic field and the {\em anti}-polarization compete resulting in the inverse spin-switch behavior where superconducting transition temperature is increased by applying a magnetic field. This work was supported by the NSF Grant DMR-0706020 (J.S.) and by the Materials Sciences and Engineering Division, Office of Basic Energy Sciences, the US DOE (S.O.). [Preview Abstract] |
Tuesday, March 22, 2011 3:18PM - 3:30PM |
L34.00005: Magnetoelectric Coupling in P(VDF-TRFE)/LCMO Heterojunctions Anil Kumar, Evgeny Kirianov, Vasily Moshnyaga, Pankaj Sharma, Alexei Gruverman, Andrei Sokolov Engineered magnetoelectric heterojunctions have recently attracted significant interest due to the possibility to control magnetic properties by external electric fields. Doped lanthanum manganites are attractive candidates to use as a part of such junctions because of their strong coupling between charge, spin and lattice effects. On the other side the use of a ferroelectric (FE) as a gate electrode has dual benefits: it offers the possibility to design a non-volatile data storage device and provide large charge density change at the interface. The ferroelectric polymer, polyvinylidene fluoride (PVDF), is an interesting candidate due to its outstanding electromechanical, dielectric, and mechanical properties. Here we present results of our transport studies of La.$_{67}$Ca.$_{33}$MnO$_{3}$ /P(VDF-TrFE) heterojunction. Manganite thin films were grown by MAD technique, followed by Langmuir-Blodgett deposition of ferroelectric polymer. Results are explained by electron accumulation induced metal-insulator transition in the LCMO layer. [Preview Abstract] |
Tuesday, March 22, 2011 3:30PM - 3:42PM |
L34.00006: ABSTRACT WITHDRAWN |
Tuesday, March 22, 2011 3:42PM - 4:18PM |
L34.00007: Emergent phenomena at the heterointerface of multiferroic BiFeO$_{3}$ and ferromagnetic La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ Invited Speaker: Novel phenomena and functionalities at the heteroepitaxial complex oxide heterostructures have been attracting much scientific attention from the fundamental physics as well as the technological applications. Essentially, the charge and spin reconstruction at the interface could lead to exotic, totally unexpected state of matters at the interface, such as conductive interface between insulating materials and interfacial ferromagnetism at the proximity of antiferromagnet. In this talk, I will present a systematic study of the electronic (charge) and magnetic (spin) interactions in an all-oxide model heterostructure system consisting of the ferromagnet (FM) La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) and the multiferroic (ferroelectric (FE) and antiferromagnetic (AFM)) BiFeO$_{3}$(BFO). The study has demonstrated the existence of magnetic coupling at this interface, manifested in the form of an enhanced coercive field as well as an exchange bias. Using x-ray magnetic circular dichroism, the origin of the significant exchange bias has been attributed to a novel ferromagnetic state in the antiferromagnetic BFO sublattice at the interface with LSMO. Based on this finding, the electrical control of magnetic coupling has been explored in the field effect geometry. The magneto-transport measurement clearly demonstrates a reversible switch/control between two distinct exchange bias states by isothermally switching the FE polarization of BFO. This is an important step towards controlling magnetization with electric fields, which may enable a new class of electrically controllable spintronic devices and provide a new basis for producing electrically controllable spin polarized currents. Finally, at the end of the talk, a generic interpretation will be proposed for the understanding of magnetoelectric coupling in the current model system. [Preview Abstract] |
Tuesday, March 22, 2011 4:18PM - 4:30PM |
L34.00008: Modified Magnetotransport in Digital Manganite Superlattices Brittany Nelson-Cheeseman, Tiffany Santos, Sam Bader, Anand Bhattacharya We investigate how the series of manganite superlattices, (LaMnO$_{3}$)$_{2n}$(SrMnO$_{3}$)$_{n}$, responds to an out-of-plane magnetic field in order to better understand how the magnetism and magnetotransport are modified in a short period superlattice. The n=1 superlattice shows magnetotransport and magnetic hysteresis similar to the random alloy with positive low field magnetoresistance (MR) due to anisotropic magnetoresistance (AMR) and negative MR at high fields due to colossal magnetoresistance (CMR). However, the n=2 superlattice behaves differently with large negative MR at high fields, and no positive low field MR for T$<$100K. The lack of positive low field MR has also been seen in La$_{2/3}$Sr$_{1/3}$MnO$_{3}$ films with perpendicular magnetic anisotropy, suggesting that the n=2 sample moments contain an out-of-plane, canted or frustrated component at low fields. The reemergence of positive low field MR for the n=2 sample above 100K indicates that the driving force for the different moment orientation is strongly temperature dependent. [Preview Abstract] |
Tuesday, March 22, 2011 4:30PM - 4:42PM |
L34.00009: La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ Epitaxial Films on SrTiO$_{3}$(001): Interface Effects \& Electronic Distribution J.-S. Lee, D.A. Arena, C.-C. Kao, P. Yu, R. Ramesh La$_{1-x}$Sr$_{x}$MnO$_{3}$ is an attractive material for incorporation into spin-dependent electronic devices and optimally doped La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) is among the most widely studied colossal magneto-resistance materials. Using a combination of soft x-ray absorption spectroscopy and hard x-ray reflectivity, we found that epitaxial films of LSMO grown on STO(001) substrates exhibit an inhomogeneous 3d electron-distribution along surface normal direction, divided between an intermediate layer (enriched in Mn$^{3+}$) and a nominal mixed-valence layer (Mn$^{3+}$ \& Mn$^{4+}$) of LSMO. This electronic redistribution near the interface is in turn correlated with an unusual remanent magnetic state. [Preview Abstract] |
Tuesday, March 22, 2011 4:42PM - 4:54PM |
L34.00010: La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ Epitaxial Films on SrTiO$_{3}$(001): Interface Effects \& Magnetic Configuration D.A. Arena, J.-S. Lee, C.S. Nelson, C.-C. Kao, P. Yu, R. Ramesh, R. Fan, C.J. Kinane, S. Langridge Mixed valence manganites, in which a delicate interaction between electronic, orbital, magnetic and structural degrees of freedom produces rich phase diagrams reflecting the competing, nearly-degenerate ground states, have been under intense investigation for decades. We present evidence for an unusual magnetic configuration in La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) epitaxial films grown on SrTiO$_{3}$(001) substrates. At low temperatures, the remanent state of the near-surface region in thick LSMO films is aligned anti-parallel to the the applied magnetic field. This unusual magnetic configuration is also correlated with an in-plane structural fluctuation, as measured by x-ray diffraction. We suggest that the unexpected magnetic ordering in these films may also be associated with an orbital reconstruction of the Mn $e_g$ orbitals. [Preview Abstract] |
Tuesday, March 22, 2011 4:54PM - 5:06PM |
L34.00011: Magnetoelectric coupling at the interface of BiFeO$_3$/La$_{0.7}$Sr$_{0.3}$MnO$_3$ multilayers Maria J. Calderon, R. Yu, S. Liang, J. Salafranca, S. Dong, S. Yunoki, A. Moreo, E. Dagotto, L. Brey Magnetoelectric coupling has recently been demonstrated in a system composed of the ferromagnetic manganite La$_{0.7}$Sr$_ {0.3}$MnO$_3$ (LSMO) and the ferroelectric antiferromagnetic BiFeO$_3$ (BFO) [1,2]. Using a realistic microscopic model we study the effects of the charge redistribution and orbital reconstruction on the LSMO/BFO interface ground state. We find that the BFO interface (ferro)magnetism is affected by the charge density at the interface which, in turn, can be modified by the ferroelectric polarization on BFO. This interface induced magnetoelectric coupling leads to the recently observed electric field controlled exchange bias.\\[4pt] [1] S. M. Wu et al, Nature Materials 9, 756 (2010).\\[0pt] [2] P. Yu et al, Phys. Rev. Lett. 105, 027201 (2010). [Preview Abstract] |
Tuesday, March 22, 2011 5:06PM - 5:18PM |
L34.00012: Modulation doping of double-exchange ferromagnetism in an antiferromagnetic manganite: Theory and Synthesis Anand Bhattacharya, T.S. Santos, B.J. Kirby, Sanjeev Kumar, S.J. May, J.A. Borchers, B.B. Maranville, J. Zarestky, S.G.E. te Velthuis, Jeroen van den Brink In this talk we shall discuss the concepts that underlie modulation doping in the context of manganites, particularly the high bandwidth La$_{1-x}$Sr$_{x}$MnO$_{3}$, and how modulation doped structures are realized using oxide-MBE based techniques. The transport and magnetic properties of modulation doped antiferromagnetic digital superlattices of (LaMnO$_{3})_{1}$/(SrMnO$_{3})_{1}$ will be discussed in the context of theoretical ideas about exchange interactions in these materials going back to the seminal work of de Gennes, and compared to similar structures in other parts of the La$_{1-x}$Sr$_{x}$MnO$_{3}$ phase diagram. [Preview Abstract] |
Tuesday, March 22, 2011 5:18PM - 5:30PM |
L34.00013: Modulation doping of double-exchange ferromagnetism in an antiferromagnetic manganite: Magnetic Structure T.S. Santos, A. Bhattacharya, S.G.E. te Velthuis, B.J. Kirby, J.A. Borchers, B.B. Maranville, S.J. May, S. Kumar, J. van den Brink, J. Zarestky In his pioneering work, de Gennes described a canted antiferromagnetic (AF) state that arises when mobile carriers are added to an insulating AF manganite. However, attempts to realize this canted AF state have been impeded by phase segregation into mixed F and AF phases for x=0.1-0.2. Using a digital synthesis technique to carry out modulation doping of charge carriers into an AF host near x=0.5, we exploit the competing double-exchange and superexchange interactions to realize the canted AF state predicted by de Gennes. We observed the canted AF state using polarized neutron reflectometry and neutron diffraction using polarized neutrons and polarization analysis. Theoretical consideration using the two-orbital model shows that these additional carriers cause a local enhancement of F double-exchange with respect to AF superexchange, resulting in local canting of the AF spins, where the canting angle depends on the doping level. We observe that the canting angle varies with the spreading of charge near the delta-doped layer. Funded by DOE-BES: Scientific User Facilities Div. \& Div. of Materials Science \& Engineering, and US Dept. of Commerce [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