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Peria WK, Katz MB, Wang JP, Crowell PA, Gopman DB. Low Gilbert damping and high perpendicular magnetic anisotropy in an Ir-coupled L1 0-FePd-based synthetic antiferromagnet. Sci Rep 2024; 14:13290. [PMID: 38858412 PMCID: PMC11164879 DOI: 10.1038/s41598-024-63475-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 05/29/2024] [Indexed: 06/12/2024] Open
Abstract
Thin ferromagnetic films possessing perpendicular magnetic anisotropy derived from the crystal lattice can deliver the requisite magnetocrystalline anisotropy density for thermally stable magnetic memory and logic devices at the single-digit-nm lateral size. Here, we demonstrate that an epitaxial synthetic antiferromagnet can be formed from L10 FePd, a candidate material with large magnetocrystalline anisotropy energy, through insertion of an ultrathin Ir spacer. Tuning of the Ir spacer thickness leads to synthetic antiferromagnetically coupled FePd layers, with an interlayer exchange field upwards of 0.6 T combined with a perpendicular magnetic anisotropy energy of 0.95 MJ/m3 and a low Gilbert damping of 0.01. Temperature-dependent ferromagnetic resonance measurements show that the Gilbert damping is mostly insensitive to temperature over a range of 20 K up to 300 K. In FePd|Ir|FePd trilayers with lower interlayer exchange coupling, optic and acoustic dynamic ferromagnetic resonance modes are explored as a function of temperature. The ability to engineer low damping and large interlayer exchange coupling in FePd|Ir|FePd synthetic antiferromagnets with high perpendicular magnetic anisotropy could prove useful for high performance spintronic devices.
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Affiliation(s)
- William K Peria
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Michael B Katz
- Materials Science and Engineering Division, NIST, Gaithersburg, MD, 20899, USA
| | - Jian-Ping Wang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Paul A Crowell
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Daniel B Gopman
- Materials Science and Engineering Division, NIST, Gaithersburg, MD, 20899, USA.
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2
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Zhang D, Huang D, Wu RJ, Lattery D, Liu J, Wang X, Gopman DB, Mkhoyan KA, Wang JP, Wang X. Low Gilbert damping and high thermal stability of Ru-seeded L1 0-phase FePd perpendicular magnetic thin films at elevated temperatures. APPLIED PHYSICS LETTERS 2020; 117:10.1063/5.0016100. [PMID: 33642608 PMCID: PMC7909870 DOI: 10.1063/5.0016100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Bulk perpendicular magnetic anisotropy materials are proposed to be a promising candidate for next-generation ultrahigh density and ultralow energy-consumption spintronic devices. In this work, we experimentally investigate the structure, thermal stability, and magnetic properties of FePd thin films seeded by a Ru layer. An fcc-phase Ru layer induces the highly-ordered L10-phase FePd thin films with perpendicular magnetic anisotropy (K u ~ 10.1 Merg/cm3). The thermal stability of FePd samples is then studied through the annealing process. It is found that a K u ~ 6.8 Merg/cm3 can be obtained with the annealing temperature of 500 °C. In addition, the damping constant α, an important parameter for switching current density, is determined as a function of the testing temperature. We observe that α increases from 0.006 to 0.009 for as-deposited FePd sample and from 0.006 to 0.012 for 400 °C-annealed FePd sample as the testing temperature changes from 25 °C to 150 °C. These results suggest that Ru-seeded FePd provides great potential in scaling perpendicular magnetic tunnel junctions below 10 nm for applications in ultralow energy-consumption spintronic devices.
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Affiliation(s)
- Delin Zhang
- Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Dingbin Huang
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Ryan J Wu
- Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455 USA
| | - Dustin Lattery
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Jinming Liu
- Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Xinjun Wang
- Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 USA
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Daniel B Gopman
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - K Andre Mkhoyan
- Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455 USA
| | - Jian-Ping Wang
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Xiaoxia Wang
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 USA
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Wang X, Krylyuk S, Josell D, Zhang D, Wang JP, Gopman DB. Effect of oblique versus normal deposition orientation on the properties of perpendicularly magnetized L1 0 FePd thin films. IEEE TRANSACTIONS ON MAGNETICS 2020; 11:10.1109/LMAG.2020.3012081. [PMID: 33654328 PMCID: PMC7918265 DOI: 10.1109/lmag.2020.3012081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Materials such as L10 Fe-based alloys with perpendicular magnetic anisotropy derived from crystal structure have the potential to deliver higher thermal stability of magnetic memory elements compared to materials whose anisotropy is derived from surfaces and interfaces. A number of processing parameters enable control of the quality and texture of L10 FePd among them, including substrate, deposition temperature, pressure and seed and buffer layer. The angle of inclination between the substrate and the sputtering target can also impact the texture of L10 crystallization of sputtered Fe-Pd and magnetic properties of the derived thin films. This study examines the difference between FePd layers that have been magnetron sputter deposited on Cr(15 nm)/Pt, Ir, or Ru(4 nm)/FePd (8 nm)/Ru(2 nm)/Ta(3 nm) substrate layers at an oblique angle (30° tilt from the sputtering target) versus normal incidence (target facing the substrate). X-ray diffraction, ferromagnetic resonance spectroscopy and vibrating sample magnetometry were used to compare the degree of L10 order and static and dynamic properties of films deposited under both conditions. The films grown using the oblique orientation exhibit a stronger degree of L10 orientation, a larger magnetic anisotropy energy and a lower Gilbert damping, on all three buffer layers.
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Affiliation(s)
- Xinjun Wang
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
- Department of Electrical Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Sergiy Krylyuk
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Daniel Josell
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Delin Zhang
- Department of Electrical Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Jian-Ping Wang
- Department of Electrical Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Daniel B. Gopman
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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Luo F, Wong QY, Li S, Tan F, Lim GJ, Wang X, Lew WS. Dependence of spin-orbit torque effective fields on magnetization uniformity in Ta/Co/Pt structure. Sci Rep 2019; 9:10776. [PMID: 31346218 PMCID: PMC6658513 DOI: 10.1038/s41598-019-47125-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 06/25/2019] [Indexed: 11/09/2022] Open
Abstract
The spin-orbit torque (SOT) effective fields, namely field-like and damping-like terms, depend on the thicknesses of heavy metal (HM) and ferromagnetic metal (FM) layers, in a stack comprising of HM/FM/HM or oxide. In this work, we report on the dependence of the SOT effective fields on the magnetization uniformity in the wires comprising of Ta/Co/Pt layer structure. SOT dependence on magnetization uniformity dependence was investigated by concurrent variation of the magnetization uniformity in Co layer and characterization of the SOT effective fields in each wire which excludes the layer thickness dependence influences. Our experimental results reveal that the field-like term decreases while the damping-like term increases with increasing Co magnetization uniformity. The magnetization uniformity influence on the effective fields is attributed to the spin Hall effect, which contributes to the SOT.
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Affiliation(s)
- Feilong Luo
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Qi Ying Wong
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Sihua Li
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Funan Tan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Gerard Joseph Lim
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Xuan Wang
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
- Department of Physics, School of Science, Lanzhou University of Technology, Lanzhou, 730050, PR China
| | - Wen Siang Lew
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore.
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Mishra R, Yu J, Qiu X, Motapothula M, Venkatesan T, Yang H. Anomalous Current-Induced Spin Torques in Ferrimagnets near Compensation. PHYSICAL REVIEW LETTERS 2017; 118:167201. [PMID: 28474947 DOI: 10.1103/physrevlett.118.167201] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Indexed: 06/07/2023]
Abstract
While current-induced spin-orbit torques have been extensively studied in ferromagnets and antiferromagnets, ferrimagnets have been less studied. Here we report the presence of enhanced spin-orbit torques resulting from negative exchange interaction in ferrimagnets. The effective field and switching efficiency increase substantially as CoGd approaches its compensation point, giving rise to 9 times larger spin-orbit torques compared to that of a noncompensated one. The macrospin modeling results also support efficient spin-orbit torques in a ferrimagnet. Our results suggest that ferrimagnets near compensation can be a new route for spin-orbit torque applications due to their high thermal stability and easy current-induced switching assisted by negative exchange interaction.
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Affiliation(s)
- Rahul Mishra
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Jiawei Yu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Xuepeng Qiu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials & School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - M Motapothula
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
| | - T Venkatesan
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117542, Singapore
- Integrated Science and Engineering Department, National University of Singapore, Singapore 117542, Singapore
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
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Deterministic Spin-Orbit Torque Induced Magnetization Reversal In Pt/[Co/Ni] n /Co/Ta Multilayer Hall Bars. Sci Rep 2017; 7:972. [PMID: 28428617 PMCID: PMC5430536 DOI: 10.1038/s41598-017-01079-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 03/27/2017] [Indexed: 11/26/2022] Open
Abstract
Spin-orbit torque (SOT) induced by electric current has attracted extensive attention as an efficient method of controlling the magnetization in nanomagnetic structures. SOT-induced magnetization reversal is usually achieved with the aid of an in-plane bias magnetic field. In this paper, we show that by selecting a film stack with weak out-of-plane magnetic anisotropy, field-free SOT-induced switching can be achieved in micron sized multilayers. Using direct current, deterministic bipolar magnetization reversal is obtained in Pt/[Co/Ni]2/Co/Ta structures. Kerr imaging reveals that the SOT-induced magnetization switching process is completed via the nucleation of reverse domain and propagation of domain wall in the system.
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Choi YH, Yoshimura Y, Kim KJ, Lee K, Kim TW, Ono T, You CY, Jung MH. Field-driven domain wall motion under a bias current in the creep and flow regimes in Pt/[CoSiB/Pt]N nanowires. Sci Rep 2016; 6:23933. [PMID: 27030379 PMCID: PMC4814914 DOI: 10.1038/srep23933] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 03/16/2016] [Indexed: 11/09/2022] Open
Abstract
The dynamics of magnetic domain wall (DW) in perpendicular magnetic anisotropy Pt/[CoSiB/Pt]N nanowires was studied by measuring the DW velocity under a magnetic field (H) and an electric current (J) in two extreme regimes of DW creep and flow. Two important findings are addressed. One is that the field-driven DW velocity increases with increasing N in the flow regime, whereas the trend is inverted in the creep regime. The other is that the sign of spin current-induced effective field is gradually reversed with increasing N in both DW creep and flow regimes. To reveal the underlying mechanism of new findings, we performed further experiment and micromagnetic simulation, from which we found that the observed phenomena can be explained by the combined effect of the DW anisotropy, Dzyaloshinskii-Moriya interaction, spin-Hall effect, and spin-transfer torques. Our results shed light on the mechanism of DW dynamics in novel amorphous PMA nanowires, so that this work may open a path to utilize the amorphous PMA in emerging DW-based spintronic devices.
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Affiliation(s)
- Y H Choi
- Department of Physics, Sogang University, Seoul 121-742 Korea
| | - Y Yoshimura
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K-J Kim
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K Lee
- Institute of Physics, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - T W Kim
- Department of Advanced Materials Engineering, Sejong University, Seoul 143-747 Korea
| | - T Ono
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - C-Y You
- Department of Physics, Inha University, Incheon 402-751, Korea
| | - M H Jung
- Department of Physics, Sogang University, Seoul 121-742 Korea
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Ho P, Tu KH, Zhang J, Sun C, Chen J, Liontos G, Ntetsikas K, Avgeropoulos A, Voyles PM, Ross CA. Domain configurations in Co/Pd and L10-FePt nanowire arrays with perpendicular magnetic anisotropy. NANOSCALE 2016; 8:5358-5367. [PMID: 26883011 DOI: 10.1039/c5nr08865h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Perpendicular magnetic anisotropy [Co/Pd]15 and L10-FePt nanowire arrays of period 63 nm with linewidths 38 nm and 27 nm and film thickness 27 nm and 20 nm respectively were fabricated using a self-assembled PS-b-PDMS diblock copolymer film as a lithographic mask. The wires are predicted to support Néel walls in the Co/Pd and Bloch walls in the FePt. Magnetostatic interactions from nearest neighbor nanowires promote a ground state configuration consisting of alternating up and down magnetization in adjacent wires. This was observed over ∼75% of the Co/Pd wires after ac-demagnetization but was less prevalent in the FePt because the ratio of interaction field to switching field was much smaller. Interactions also led to correlations in the domain wall positions in adjacent Co/Pd nanowires. The reversal process was characterized by nucleation of reverse domains, followed at higher fields by propagation of the domains along the nanowires. These narrow wires provide model system for exploring domain wall structure and dynamics in perpendicular anisotropy systems.
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Affiliation(s)
- Pin Ho
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA02139, USA.
| | - Kun-Hua Tu
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA02139, USA.
| | - Jinshuo Zhang
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA02139, USA.
| | - Congli Sun
- Department of Materials Science and Engineering, University of Wisconsin, Madison, WI53706, USA
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore, Singapore 119077, Singapore
| | - George Liontos
- Department of Materials Science and Engineering, University of Ioannina, University Campus - Dourouti, Ioannina 45110, Greece
| | - Konstantinos Ntetsikas
- Department of Materials Science and Engineering, University of Ioannina, University Campus - Dourouti, Ioannina 45110, Greece
| | - Apostolos Avgeropoulos
- Department of Materials Science and Engineering, University of Ioannina, University Campus - Dourouti, Ioannina 45110, Greece
| | - Paul M Voyles
- Department of Materials Science and Engineering, University of Wisconsin, Madison, WI53706, USA
| | - Caroline A Ross
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA02139, USA.
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