Bulletin of the American Physical Society
2014 Annual Meeting of the Mid-Atlantic Section of the APS
Volume 59, Number 9
Friday–Sunday, October 3–5, 2014; University Park, Pennsylvania
Session E6: Condensed Matter Physics |
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Chair: Anthony Richardella, Pennsylvania State University Room: Life Sciences Building 011 |
Saturday, October 4, 2014 3:30PM - 3:42PM |
E6.00001: Electric field tuning of anisotropic magneto-transport properties of two-dimensional electron gas at the surface of SrTiO3 Ludi Miao, Renzhong Du, Yuewei Yin, Qi Li Two-dimensional electron gases (2DEGs) at transition metal oxide surfaces and interfaces have attracted much attention due to their fascinating exotic properties such as superconductivity, large magneto-resistance and ferromagnetism. We have created a 2DEG at the (001) surface of SrTiO3 by Ar$+$-irradiation and measured its anisotropic magneto-resistance (AMR). The 2DEG exhibits a fully metallic behavior with a low temperature mobility as large as 5500 cm2V-1s-1. At low temperatures, a mixture of a four-fold component which reflects the four-fold symmetry of the SrTiO3 Fermi surface and only appears in a two-dimensional system as well as a two-fold component which is due to the Lorentz force effect are observed in the AMR. These components can be separated by Fourier analysis. Moreover, the four-fold component can be modulated by electric field applied by a back gate. The electric field induced redistribution of oxygen deficiencies which are created at the SrTiO3 surface during Ar$+$-irradiation and hence the tuning of dimensionality of the system are responsible for the modulation on AMR. [Preview Abstract] |
Saturday, October 4, 2014 3:42PM - 3:54PM |
E6.00002: Ferroelectric phase transition in EBTO thin films using second harmonic generation Guerau Cabrera, Sam Mathers, Weiwei Li, Hao Yang, Mikel Holcomb Europium Barium Titanate (Eu$_{0.5}$Ba$_{0.5}$TiO$_{3}$) or EBTO in bulk form is a novel single-phase multiferoic material that exhibits ferroelectric (Curie temp $\sim$ 213K) and G-type antiferromagnetic (Neel temp $\sim$ 1.9K) properties. Oxygen vacancies have been shown to play a role in room temperature ferromagnetism (HfO$_2$, ZnO, TiO$_2$) and have been reported to increase the Curie temperature of EuO films. EBTO films were grown on SrTiO$_3$ (STO) substrates by pulsed laser deposition (PLD). We performed a temperature dependence study using second harmonic generation (SHG) and found the SHG signal to change as a function of temperature indicating a phase tranistion from paraelectric to ferroelectric in these EBTO films. [Preview Abstract] |
Saturday, October 4, 2014 3:54PM - 4:06PM |
E6.00003: Enhancement of tunneling electroresistance in multiferroic tunnel junctions by ferroelectric driven phase transition Y.W. Yin, J.D. Burton, Y-M. Kim, A.Y. Borisevich, S.J. Pennycook, S.M. Yang, T.W. Noh, A. Gruverman, X.G. Li, E.Y. Tsymbal, Qi Li A multiferroic tunnel junction (MFTJ), employing a ferroelectric (FE) barrier sandwiched between two ferromagnetic (FM) electrodes has become a promising multifunctional device for practical use. Large resistance difference between states is critical for utilizing MFTJ as resistance switch. To increase the tunneling electroresistance (TER) effect, we have designed a La0.7Sr0.3MnO3(LSMO)/BaTiO3(BTO)/La0.5Ca0.5MnO3(LCMO)/LSMO MFTJ in which a FM metallic to antiferromagnetic (AFM) insulating phase transition in LCMO due to interfacial charge doping occurs when the FE polarization of BTO is pointing opposite to LCMO. The metal to insulator transition of LCMO will increase the tunneling barrier width which was verified by transport fitting. While the FM to AFM transition of LCMO will reduce the transmission probability of spin polarized tunneling electrons, which also suppresses tunneling magnetoresistance effect. This is supported by high magnetic field measurement demonstrating that the suppressed AFM order leads to the TER reduction. Both the barrier width increase and transmission probability reduction will significantly increase the resistance difference between two polarization states, and an increase of TER from 30{\%} to 10,000{\%} was obtained. [Preview Abstract] |
Saturday, October 4, 2014 4:06PM - 4:18PM |
E6.00004: Proposed method of optical spin read-out in a quantum dot using the AC Stark effect Edward Flagg, Gary Lander, Cabot Zabriskie We propose a method to read-out the spin-state of a single electron trapped in a quantum dot via a cycling transition induced by the AC Stark effect. Optical spin initialization and manipulation are allowed by a magnetic field in the Voigt configuration, which modifies the polarization selection rules of the transitions. The lack of a cycling transition in the Voigt configuration, however, makes read-out of the spin-state very difficult. We show that cycling transitions can be made possible by a red-detuned, circularly-polarized laser, which modifies the spin eigenstates and polarization selection rules via the AC Stark effect. [Preview Abstract] |
Saturday, October 4, 2014 4:18PM - 4:30PM |
E6.00005: Fractional angular momentum in cold atom systems Yuhe Zhang, Ganesh Jaya Sreejith, Nathan D. Gemelke, Jainendra K. Jain The statistics of bosons or fermions are manifest through even or odd relative angular momentum of a pair. We show theoretically that a pair of ``impurity atoms'' immersed in a fractional quantum Hall state possesses, effectively, a fractional relative angular momentum, which can be interpreted in terms of fractional braid statistics. We propose that the fractionalization of the angular momentum can be detected directly through the measurement of the pair correlation function in rotating ultra-cold atomic systems in the fractional quantum Hall regime. Such a measurement will also provide direct evidence for the effective magnetic field, resulting from Berry phases arising from attached vortices, and of excitations with fractional particle number, analogous to fractional charge of electron fractional quantum Hall effect. [Preview Abstract] |
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