AVS2016 Session MI-TuP: MIND Poster Session
Time Period TuP Sessions | Topic MI Sessions | Time Periods | Topics | AVS2016 Schedule
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MI-TuP-1 Static and Dynamic Magnetic Properties of FeGa/NiFe Multilayer Heterostructures for Multiferroic Applications
Colin Rementer, Qiang Xu, Paul Nordeen, Gregory Carman, Yuanxun Wang, Jane P. Chang (University of California Los Angeles) Iron-gallium (FeGa) is one of the most promising magnetic materials for use in composite multiferroics due to its high piezomagnetic coefficient (3 ppm/Oe) and high stiffness (70 GPa). It has been integrated into several multiferroic systems, but generally in MHz range or below.1 In order to make it suitable for high frequency (GHz) applications, metalloid dopants have been used to soften magnetic materials and enhance their frequency dependent properties, but at the cost of the saturation magnetization as well as magnetoelastic properties.2 A viable approach to circumvent this trade-off problem is to integrate a magnetic material with complementary properties into magnetic heterostructures. In this work, multilayer laminates were fabricated with FeGa and NiFe, a material with excellent properties in high frequency regimes. FeGa (hard) and NiFe (soft) were sputtered via alloy targets with compositions Fe85Ga15 and Ni81Fe19 (at%) into multilayers with layer thicknesses ranging from 3-50 nm, with FeGa being used as the first and last layer in the stack. XPS confirmed the composition and showed there was no intermixing of the layers. Static magnetic properties were evaluated via SQUID magnetometry, and it was found that the incorporation of NiFe layers reduced the coercivity by up to 85%, from 30 Oe to 4 Oe. FMR studies showed a reduction of the linewidth of up to 50%, from 70 Oe to 38 Oe. It is believed that this effect is largely due to the decrease of magnetic anisotropy dispersion in the multilayers.3 The multilayer films maintained a high magnetostriction of up to 190 ppm, on the same order of magnitude as giant magnetostrictive materials such as thin film Terfenol-D.4 FeGa/NiFe heterostructures have been shown to be an excellent candidate for strain-coupled microwave multiferroics. References: 1.M Hamashima, C Saito, M Nakamura and H Muro, ECJ (5), 1-7 (2012). 2.J Lou, RE Insignares, Z Cai, KS Ziemer, M Liu and NX Sun, APL (18) (2007). 3.R. Nakatani, T Kobayashi, S Ootomo and N Kumasaka, JJAP 27 (6) (1988). 4. KP Mohanchandra, SV Prikhodko, KP Wetzlar, WY Sun, P Nordeen and G. P. Carman. AIP Advances 5 097119 (2015). |
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MI-TuP-2 The Microstructure and Isotope Effects on Spin Response in Organic Spintronic Devices
Nuradhika Herath, Jong Keum, Honghai Zhang, Kunlun Hong, Jacek Jakowski, Jingsong Huang, Jim Browning, Steven Bennett, Chris Rouleau, Ilia N. Ivanov, Valeria Lauter (Oak Ridge National Laboratory) There is currently a strong drive to realize magnetoelectronic heterostructures with controls of magnetic ordering and electron-spin transport for use in the next generation spintronic devices. One proposed method to gain such controls is the use organic spintronics (OS). The general configuration of OS device consists of two ferromagnetic (FM) electrodes separated by an organic layer to form a sandwich structure. While basic concepts of OS device have been demonstrated, there is very little understanding about the detailed effects of the organic layer and the interface interactions within the multilayers on the physical properties of the system. Amongst the difficulties limiting high performances OS are the subtle structural variations, including i.e., interdiffusion of FM electrode into the soft organic layer during the fabrication. Using the depth sensitive method of polarized neutron reflectometry we have been able to probe the fine details of the structural and magnetic properties of prototype spintronic devices (STO\\LSMO\polymer\Co\Ag). We fabricated heterostructures using two electron conducting polymers (P3HT and PFO) and their deuterated substitutions to study the isotope effect of polymer layer in the spintronic devices. While our main goal is on understanding the effect of deuterium substitution on the spin-dependent electron transport, in this presentation, we will focus the details of the structural and magnetization profiles on both LSMO\Polymer and polymer\Co interfaces and their impact on the coupling between magnetic layers. Acknowledgements: This work was sponsored by Oak Ridge National Laboratory Directed Research and Development (LDRD 7938) and conducted at the Center for Nanophase Materials Sciences (CNMS) and Spallation Neutron Source (SNS), which are sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. |