1
|
Janardhanan S, Mielcarek S, Głowiński H, Kowacz M, Kuświk P, Krawczyk M, Trzaskowska A. Investigation of spin wave dynamics in Au/CoFeB/Au multilayers with perpendicular magnetic anisotropy. Sci Rep 2023; 13:22494. [PMID: 38110449 PMCID: PMC10728143 DOI: 10.1038/s41598-023-49859-8] [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: 09/01/2023] [Accepted: 12/12/2023] [Indexed: 12/20/2023] Open
Abstract
We have carried out an experimental investigation of the spin-wave dynamics in the Au/CoFeB/Au multilayer consisting of a ferromagnetic film with thicknesses of 0.8, 0.9 and 1.0 nm. We employed the Brillouin light scattering spectroscopy to measure the frequency of the spin waves in dependence on the wave vector. Additionally, we characterized the samples by ferromagnetic resonance measurements. We found that the considered samples exhibit perpendicular magnetic anisotropy with low damping, indicating small pumping effects. Furthermore, we found a nonreciprocal dispersion relation pointing at a non-negligible Dzyaloshinskii-Moriya interaction. These results make the Au/CoFeB/Au multilayer a compelling subject for further analysis and as a potential material for future applications within magnonics.
Collapse
Affiliation(s)
- S Janardhanan
- ISQI, Faculty of Physics, Adam Mickiewicz University, Poznan, Poland.
| | - S Mielcarek
- ISQI, Faculty of Physics, Adam Mickiewicz University, Poznan, Poland
| | - H Głowiński
- Institute of Molecular Physics, Polish Academy of Science, Poznan, Poland
| | - M Kowacz
- Institute of Molecular Physics, Polish Academy of Science, Poznan, Poland
| | - P Kuświk
- Institute of Molecular Physics, Polish Academy of Science, Poznan, Poland
| | - M Krawczyk
- ISQI, Faculty of Physics, Adam Mickiewicz University, Poznan, Poland
| | - A Trzaskowska
- ISQI, Faculty of Physics, Adam Mickiewicz University, Poznan, Poland
| |
Collapse
|
2
|
Gupta NK, Kumar A, Pandey L, Hait S, Barwal V, Khan A, Mishra V, Sharma N, Kumar N, Chaudhary S. High temperature stability in few atomic layer MoS 2 based thin film heterostructures: structural, static and dynamic magnetization properties. NANOSCALE 2023. [PMID: 37470330 DOI: 10.1039/d3nr01719b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
Layered transition metal dichalcogenides (TMDs) have shown commendable properties for spintronic applications. From the device perspective, the structural quality of the TMD as well as its interface with the adjacent ferromagnetic (FM) layer is of paramount importance. Here, we present the spin-dynamic behaviour in the widely studied TMDs, i.e., MoS2 using Co60Fe20B20 (CoFeB), i.e., in MoS2(1-4 layers)/CoFeB(4-15 nm) heterostructures, both in the as-grown state and in the in situ annealed state (400 °C in a vacuum). Raman spectroscopy revealed systematic variation in the separation (δ) between the characteristic Raman shifts corresponding to the E2g and A1gvis-à-vis the number of layers (nL) of MoS2. The analysis of the ferromagnetic resonance (FMR) spectroscopy measurements performed on these heterostructures revealed the spin pumping from CoFeB to the MoS2 layer as evidenced by the ∼49% (∼51%) enhancement in the effective damping parameter with respect to the damping parameter of bare as-deposited (annealed) CoFeB films. This enhancement is attributed to the spin-pumping owing to the high spin-orbit coupling of monolayer MoS2. The latter is also confirmed by density functional theory calculations. By finding the effective spin mixing conductance of the MoS2/CoFeB interface, the effective spin current density in the MoS2 layer is estimated to increase from ∼0.3 to 0.7 MA m-2 with CoFeB thickness for both the as-deposited and annealed heterostructures. Furthermore, the δ vs. nL curve of the as-deposited heterostructure did not show any significant change upon annealing, which demonstrated that the spin transport and magnetic properties of these heterostructures remained unaffected even after annealing at a high temperature of 400 °C. Hence, this establishes the high thermal stability of the sputter grown MoS2/CoFeB heterostructures. Thus, this study highlights the important role of MoS2 as an efficient spin current-generating source for spin-orbit torque based magnetic memory applications, given the high-temperature stability and high-quality monolayers of MoS2 and its excellent performance with CoFeB thin films.
Collapse
Affiliation(s)
- Nanhe Kumar Gupta
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
| | - Amar Kumar
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
| | - Lalit Pandey
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
| | - Soumyarup Hait
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
| | - Vineet Barwal
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
| | - Amir Khan
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
| | - Vireshwar Mishra
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
| | - Nikita Sharma
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
| | - Nakul Kumar
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
| | - Sujeet Chaudhary
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India.
| |
Collapse
|
3
|
Perpendicular magnetic anisotropy, tunneling magnetoresistance and spin-transfer torque effect in magnetic tunnel junctions with Nb layers. Sci Rep 2023; 13:3454. [PMID: 36859656 PMCID: PMC9977854 DOI: 10.1038/s41598-023-29752-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 02/09/2023] [Indexed: 03/03/2023] Open
Abstract
Nb and its compounds are widely used in quantum computing due to their high superconducting transition temperatures and high critical fields. Devices that combine superconducting performance and spintronic non-volatility could deliver unique functionality. Here we report the study of magnetic tunnel junctions with Nb as the heavy metal layers. An interfacial perpendicular magnetic anisotropy energy density of 1.85 mJ/m2 was obtained in Nb/CoFeB/MgO heterostructures. The tunneling magnetoresistance was evaluated in junctions with different thickness combinations and different annealing conditions. An optimized magnetoresistance of 120% was obtained at room temperature, with a damping parameter of 0.011 determined by ferromagnetic resonance. In addition, spin-transfer torque switching has also been successfully observed in these junctions with a quasistatic switching current density of 7.3 [Formula: see text] A/cm2.
Collapse
|
4
|
Almeida TP, Lequeux S, Palomino A, Sousa RC, Fruchart O, Prejbeanu IL, Dieny B, Masseboeuf A, Cooper D. Quantitative Visualization of Thermally Enhanced Perpendicular Shape Anisotropy STT-MRAM Nanopillars. NANO LETTERS 2022; 22:4000-4005. [PMID: 35576455 DOI: 10.1021/acs.nanolett.2c00597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Perpendicular shape anisotropy (PSA) offers a practical solution to downscale spin-transfer torque magnetoresistive random-access memory (STT-MRAM) beyond the sub-20 nm technology node while retaining thermal stability. However, our understanding of the thermomagnetic behavior of PSA-STT-MRAM is often indirect, relying on magnetoresistance measurements and micromagnetic modeling. Here, the magnetism of a NiFe PSA-STT-MRAM nanopillar is investigated using off-axis electron holography, providing spatially resolved magnetic information as a function of temperature. Magnetic induction maps reveal the micromagnetic configuration of the NiFe storage layer (∼60 nm high, ≤20 nm diameter), confirming the PSA induced by its 3:1 aspect ratio. In situ heating demonstrates that the PSA of the storage layer is maintained up to at least 250 °C, and direct quantitative measurements reveal a moderate decrease of magnetic induction. Hence, this study shows explicitly that PSA provides significant stability in STT-MRAM applications that require reliable performance over a range of operating temperatures.
Collapse
Affiliation(s)
- Trevor P Almeida
- University of Grenoble Alpes, CEA, Leti, F-38000 Grenoble, France
- SUPA, School of Physics and Astronomy, University of Glasgow, Glascow G12 8QQ, United Kingdom
| | - Steven Lequeux
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Alvaro Palomino
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Ricardo C Sousa
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Olivier Fruchart
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Ioan-Lucian Prejbeanu
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Bernard Dieny
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - Aurélien Masseboeuf
- University of Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
| | - David Cooper
- University of Grenoble Alpes, CEA, Leti, F-38000 Grenoble, France
| |
Collapse
|
5
|
Silva AS, Sá SP, Bunyaev SA, Garcia C, Sola IJ, Kakazei GN, Crespo H, Navas D. Dynamical behaviour of ultrathin [CoFeB (t CoFeB)/Pd] films with perpendicular magnetic anisotropy. Sci Rep 2021; 11:43. [PMID: 33420134 PMCID: PMC7794473 DOI: 10.1038/s41598-020-79632-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 12/01/2020] [Indexed: 11/13/2022] Open
Abstract
CoFeB-based ultrathin films with perpendicular magnetic anisotropy are promising for different emerging technological applications such as nonvolatile memories with low power consumption and high-speed performance. In this work, the dynamical properties of [CoFeB (tCoFeB)/Pd (10 Å)]5 multilayered ultrathin films (1 Å ≤ tCoFeB ≤ 5 Å) are studied by using two complementary methods: time-resolved magneto-optical Kerr effect and broadband ferromagnetic resonance. The perpendicular magnetization is confirmed for multilayers with tCoFeB ≤ 4 Å. The effective perpendicular magnetic anisotropy reaches a clear maximum at tCoFeB = 3 Å. Further increase of CoFeB layer thickness reduces the perpendicular magnetic anisotropy and the magnetization became in-plane oriented for tCoFeB ≥ 5 Å. This behaviour is explained by considering competing contributions from surface and magnetoelastic anisotropies. It was also found that the effective damping parameter αeff decreases with CoFeB layer thickness and for tCoFeB = 4 Å reaches a value of ~ 0.019 that is suitable for microwave applications.
Collapse
Affiliation(s)
- Ana S Silva
- Departamento de Fisica e Astronomia, Faculdade de Ciências, Institute of Physics for Advanced Materials, Nanotechnology and Photonics (IFIMUP), Universidade do Porto, 4169-007, Porto, Portugal
| | - Simão P Sá
- Departamento de Fisica e Astronomia, Faculdade de Ciências, Institute of Physics for Advanced Materials, Nanotechnology and Photonics (IFIMUP), Universidade do Porto, 4169-007, Porto, Portugal
| | - Sergey A Bunyaev
- Departamento de Fisica e Astronomia, Faculdade de Ciências, Institute of Physics for Advanced Materials, Nanotechnology and Photonics (IFIMUP), Universidade do Porto, 4169-007, Porto, Portugal
| | - Carlos Garcia
- Departamento de Física y Centro Científico Tecnológico de Valparaíso-CCTVal, Universidad Técnica Federico Santa María, 2390123, Valparaíso, Chile
| | - Iñigo J Sola
- Laser Applications and Photonics Group, Applied Physics Department, University of Salamanca, 37008, Salamanca, Spain
| | - Gleb N Kakazei
- Departamento de Fisica e Astronomia, Faculdade de Ciências, Institute of Physics for Advanced Materials, Nanotechnology and Photonics (IFIMUP), Universidade do Porto, 4169-007, Porto, Portugal
| | - Helder Crespo
- Departamento de Fisica e Astronomia, Faculdade de Ciências, Institute of Physics for Advanced Materials, Nanotechnology and Photonics (IFIMUP), Universidade do Porto, 4169-007, Porto, Portugal
| | - David Navas
- Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, 28049, Madrid, Spain.
| |
Collapse
|
6
|
Xu Z, Hwee Wong GD, Tang J, Liu E, Gan W, Xu F, Lew WS. Giant Spin Hall Effect in Cu-Tb Alloy Thin Films. ACS APPLIED MATERIALS & INTERFACES 2020; 12:32898-32904. [PMID: 32608235 DOI: 10.1021/acsami.0c07441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report the giant spin current generation in CuTb alloys arising from the spin Hall effect. The maximum spin Hall angle from our CuTb-based magnetic heterostructures was found to be -0.35 ± 0.02 for Cu0.39Tb0.61. We find that the contribution of skew scattering is larger than the side jump for lower Tb concentrations (<14.9%), while the converse is true for higher Tb concentrations. Additionally, we also studied the Gilbert damping parameter, spin diffusion length, and spin-mixing conductance. Interfacial spin transparency was found to be 0.55 ± 0.03 for the CoFeB/Cu0.53Tb0.47 interface. The spin diffusion length and spin-mixing conductance of the Cu0.53Tb0.47 alloy are λsd = 2.5 ± 0.3 nm and G↓↑ = (24.2 ± 1.0) × 1015 cm-2, respectively. Our results pave a way for rare-earth metals to be used as a spin Hall material in highly efficient SOT devices.
Collapse
Affiliation(s)
- Zhan Xu
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Grayson Dao Hwee Wong
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Jiaxuan Tang
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Er Liu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Weiliang Gan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Feng Xu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Wen Siang Lew
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| |
Collapse
|
7
|
Ultrathin perpendicular magnetic anisotropy CoFeB free layers for highly efficient, high speed writing in spin-transfer-torque magnetic random access memory. Sci Rep 2019; 9:19407. [PMID: 31857596 PMCID: PMC6923472 DOI: 10.1038/s41598-019-54466-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 10/30/2019] [Indexed: 11/30/2022] Open
Abstract
Perpendicular magnetic anisotropy (PMA) ferromagnetic CoFeB with dual MgO interfaces is an attractive material system for realizing magnetic memory applications that require highly efficient, high speed current-induced magnetic switching. Using this structure, a sub-nanometer CoFeB layer has the potential to simultaneously exhibit efficient, high speed switching in accordance with the conservation of spin angular momentum, and high thermal stability owing to the enhanced interfacial PMA that arises from the two CoFeB-MgO interfaces. However, the difficulty in attaining PMA in ultrathin CoFeB layers has imposed the use of thicker CoFeB layers which are incompatible with high speed requirements. In this work, we succeeded in depositing a functional CoFeB layer as thin as five monolayers between two MgO interfaces using magnetron sputtering. Remarkably, the insertion of Mg within the CoFeB gave rise to an ultrathin CoFeB layer with large anisotropy, high saturation magnetization, and good annealing stability to temperatures upwards of 400 °C. When combined with a low resistance-area product MgO tunnel barrier, ultrathin CoFeB magnetic tunnel junctions (MTJs) demonstrate switching voltages below 500 mV at speeds as fast as 1 ns in 30 nm devices, thus opening a new realm of high speed and highly efficient nonvolatile memory applications.
Collapse
|
8
|
Li X, Sasaki T, Grezes C, Wu D, Wong K, Bi C, Ong PV, Ebrahimi F, Yu G, Kioussis N, Wang W, Ohkubo T, Khalili Amiri P, Wang KL. Predictive Materials Design of Magnetic Random-Access Memory Based on Nanoscale Atomic Structure and Element Distribution. NANO LETTERS 2019; 19:8621-8629. [PMID: 31697502 DOI: 10.1021/acs.nanolett.9b03190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Magnetic tunnel junctions (MTJs) capable of electrical read and write operations have emerged as a canonical building block for nonvolatile memory and logic. However, the cause of the widespread device properties found experimentally in various MTJ stacks, including tunneling magnetoresistance (TMR), perpendicular magnetic anisotropy (PMA), and voltage-controlled magnetic anisotropy (VCMA), remains elusive. Here, using high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy, we found that the MTJ crystallization quality, boron diffusion out of the CoFeB fixed layer, and minimal oxidation of the fixed layer correlate with the TMR. As with the CoFeB free layer, seed layer diffusion into the free layer/MgO interface is negatively correlated with the interfacial PMA, whereas the metal-oxides concentrations in the free layer correlate with the VCMA. Combined with formation enthalpy and thermal diffusion analysis that can explain the evolution of element distribution from MTJ stack designs and annealing temperatures, we further established a predictive materials design framework to guide the complex design space explorations for high-performance MTJs. On the basis of this framework, we demonstrate experimentally high PMA and VCMA values of 1.74 mJ/m2 and 115 fJ/V·m-1 with annealing stability above 400 °C.
Collapse
Affiliation(s)
- Xiang Li
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
- Inston, Inc. , Los Angeles , California 90095 , United States
- Department of Electrical Engineering , Stanford University , Stanford , California 94305 , United States
| | - Taisuke Sasaki
- National Institute for Materials Science (NIMS) , 1-2-1 Sengen , Tsukuba 305-0047 , Japan
| | - Cecile Grezes
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Di Wu
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Kin Wong
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Chong Bi
- Department of Physics , University of Arizona , Tucson , Arizona 85721 , United States
| | - Phuong-Vu Ong
- Department of Physics and Astronomy , California State University Northridge , Northridge , California 91330 , United States
| | - Farbod Ebrahimi
- Inston, Inc. , Los Angeles , California 90095 , United States
| | - Guoqiang Yu
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Nicholas Kioussis
- Department of Physics and Astronomy , California State University Northridge , Northridge , California 91330 , United States
| | - Weigang Wang
- Department of Physics , University of Arizona , Tucson , Arizona 85721 , United States
| | - Tadakatsu Ohkubo
- National Institute for Materials Science (NIMS) , 1-2-1 Sengen , Tsukuba 305-0047 , Japan
| | - Pedram Khalili Amiri
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Kang L Wang
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| |
Collapse
|
9
|
Iwata-Harms JM, Jan G, Liu H, Serrano-Guisan S, Zhu J, Thomas L, Tong RY, Sundar V, Wang PK. High-temperature thermal stability driven by magnetization dilution in CoFeB free layers for spin-transfer-torque magnetic random access memory. Sci Rep 2018; 8:14409. [PMID: 30258111 PMCID: PMC6158269 DOI: 10.1038/s41598-018-32641-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 09/12/2018] [Indexed: 11/29/2022] Open
Abstract
Spin-transfer-torque magnetic random access memory (STT-MRAM) is the most promising emerging non-volatile embedded memory. For most applications, a wide range of operating temperatures is required, for example −40 °C to +150 °C for automotive applications. This presents a challenge for STT-MRAM, because the magnetic anisotropy responsible for data retention decreases rapidly with temperature. In order to compensate for the loss of thermal stability at high temperature, the anisotropy of the devices must be increased. This in turn leads to larger write currents at lower temperatures, thus reducing the efficiency of the memory. Despite the importance of high-temperature performance of STT-MRAM for energy efficient design, thorough physical understanding of the key parameters driving its behavior is still lacking. Here we report on CoFeB free layers diluted with state-of-the-art non-magnetic metallic impurities. By varying the impurity material and concentration to modulate the magnetization, we demonstrate that the magnetization is the primary factor driving the temperature dependence of the anisotropy and thermal stability. We use this understanding to develop a simple model allowing for the prediction of thermal stability of STT-MRAM devices from blanket film properties, and find good agreement with direct measurements of patterned devices.
Collapse
Affiliation(s)
- Jodi M Iwata-Harms
- TDK - Headway Technologies, Inc., 463 S. Milpitas Boulevard, Milpitas, CA, 95035, USA.
| | - Guenole Jan
- TDK - Headway Technologies, Inc., 463 S. Milpitas Boulevard, Milpitas, CA, 95035, USA
| | - Huanlong Liu
- TDK - Headway Technologies, Inc., 463 S. Milpitas Boulevard, Milpitas, CA, 95035, USA
| | | | - Jian Zhu
- TDK - Headway Technologies, Inc., 463 S. Milpitas Boulevard, Milpitas, CA, 95035, USA
| | - Luc Thomas
- TDK - Headway Technologies, Inc., 463 S. Milpitas Boulevard, Milpitas, CA, 95035, USA
| | - Ru-Ying Tong
- TDK - Headway Technologies, Inc., 463 S. Milpitas Boulevard, Milpitas, CA, 95035, USA
| | - Vignesh Sundar
- TDK - Headway Technologies, Inc., 463 S. Milpitas Boulevard, Milpitas, CA, 95035, USA
| | - Po-Kang Wang
- TDK - Headway Technologies, Inc., 463 S. Milpitas Boulevard, Milpitas, CA, 95035, USA
| |
Collapse
|
10
|
Lattery DM, Zhang D, Zhu J, Hang X, Wang JP, Wang X. Low Gilbert Damping Constant in Perpendicularly Magnetized W/CoFeB/MgO Films with High Thermal Stability. Sci Rep 2018; 8:13395. [PMID: 30190535 PMCID: PMC6127240 DOI: 10.1038/s41598-018-31642-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 08/17/2018] [Indexed: 11/10/2022] Open
Abstract
Perpendicular magnetic materials with low damping constant and high thermal stability have great potential for realizing high-density, non-volatile, and low-power consumption spintronic devices, which can sustain operation reliability for high processing temperatures. In this work, we study the Gilbert damping constant (α) of perpendicularly magnetized W/CoFeB/MgO films with a high perpendicular magnetic anisotropy (PMA) and superb thermal stability. The α of these PMA films annealed at different temperatures (Tann) is determined via an all-optical Time-Resolved Magneto-Optical Kerr Effect method. We find that α of these W/CoFeB/MgO PMA films decreases with increasing Tann, reaches a minimum of α = 0.015 at Tann = 350 °C, and then increases to 0.020 after post-annealing at 400 °C. The minimum α observed at 350 °C is rationalized by two competing effects as Tann becomes higher: the enhanced crystallization of CoFeB and dead-layer growth occurring at the two interfaces of the CoFeB layer. We further demonstrate that α of the 400 °C-annealed W/CoFeB/MgO film is comparable to that of a reference Ta/CoFeB/MgO PMA film annealed at 300 °C, justifying the enhanced thermal stability of the W-seeded CoFeB films.
Collapse
Affiliation(s)
- Dustin M Lattery
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Delin Zhang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Jie Zhu
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Xudong Hang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Jian-Ping Wang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
| | - Xiaojia Wang
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, 55455, USA. .,Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
| |
Collapse
|
11
|
Perrissin N, Lequeux S, Strelkov N, Chavent A, Vila L, Buda-Prejbeanu LD, Auffret S, Sousa RC, Prejbeanu IL, Dieny B. A highly thermally stable sub-20 nm magnetic random-access memory based on perpendicular shape anisotropy. NANOSCALE 2018; 10:12187-12195. [PMID: 29923577 DOI: 10.1039/c8nr01365a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A new approach to increase the downsize scalability of perpendicular STT-MRAM is presented. It consists of significantly increasing the thickness of the storage layer in out-of-plane magnetized tunnel junctions (pMTJ) as compared to conventional pMTJ in order to induce a perpendicular shape anisotropy (PSA) in this layer. This PSA is obtained by depositing a thick ferromagnetic (FM) layer on top of an MgO/FeCoB based magnetic tunnel junction (MTJ) so that the thickness of the storage layer is of the order of or larger than the diameter of the MTJ pillar. In contrast to conventional spin transfer torque magnetic random access memory (STT-MRAM) wherein the demagnetizing energy opposes the interfacial perpendicular magnetic anisotropy (iPMA), in these novel memory cells, both PSA and iPMA contributions favor the out-of-plane orientation of the storage layer magnetization. Using thicker storage layers in these PSA-STT-MRAMs has several advantages. Due to the PSA, very high and easily tunable thermal stability factors can be achieved, even down to sub-10 nm diameters. Moreover, a low damping material can be used for the thick FM material thus leading to a reduction of the write current. The paper describes this new PSA-STT-MRAM concept, practical realization of such memory arrays, magnetic characterization demonstrating thermal stability factor above 200 for MTJs as small as 8 nm in diameter and possibility to maintain the thermal stability factor above 60 down to 4 nm diameter.
Collapse
Affiliation(s)
- N Perrissin
- Univ. Grenoble Alpes, CEA, CNRS, Grenoble INP*, INAC-SPINTEC, 38000 Grenoble, France.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Han X, Cui H, Liu B, Tian C, Wang J, Chen H, Yuan H. Effects of overlayer capping and lattice strain on perpendicular magnetic anisotropy of TM|FePt|MgO heterostructures. Sci Rep 2018; 8:9429. [PMID: 29930342 PMCID: PMC6013451 DOI: 10.1038/s41598-018-27424-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 06/01/2018] [Indexed: 11/28/2022] Open
Abstract
Magnetic tunnel junctions (MTJs) with ferromagnetic electrodes possessing the strong perpendicular magnetocrystalline anisotropy (PMA) are of great interest as they have a potential for realizing next-generation high-density non-volatile memory and logic chips. To date, it is an urgent and critical issue to continuously promote the PMAs through feasible modifications such as the substitution of ferromagnetic layers as well as the overlayer coating on them. Here, we perform the relativistic first principles calculations of TM|L10-FePt|MgO sandwich systems, and demonstrate that the changes in PMAs by capping TM layers are always giant and positive, e.g., PMA of Fe|FePt|MgO, the largest one among all our studied systems, is about 2 times larger than that of FePt|MgO. The interfacial PMAs at TM|FePt and FePt|MgO interfaces are extracted to be 3.31~9.40 meV and 3.32 meV, respectively, which are at least 3 times larger than 0.93 meV/ML of interior FePt layer. We illustratively verify that PMAs of TM|FePt|MgO can be turned in a large range by varying the TM layer and in-plane strain. Our results and model analyses provide useful insights for how these magnetic quantities are linked, and pave a way for the promotion of PMAs of FePt-based heterostructures via contact with TM overlayers.
Collapse
Affiliation(s)
- Xiaocui Han
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, People's Republic of China
| | - Hong Cui
- School of Mechanical Engineering, Shannxi University of Technology, Shannxi, 723001, People's Republic of China
| | - Bo Liu
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, People's Republic of China
| | - Cunling Tian
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, People's Republic of China
| | - Junzhong Wang
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, People's Republic of China
| | - Hong Chen
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, People's Republic of China
| | - Hongkuan Yuan
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, People's Republic of China.
| |
Collapse
|
13
|
Tao B, Barate P, Devaux X, Renucci P, Frougier J, Djeffal A, Liang S, Xu B, Hehn M, Jaffrès H, George JM, Marie X, Mangin S, Han X, Wang Z, Lu Y. Atomic-scale understanding of high thermal stability of the Mo/CoFeB/MgO spin injector for spin-injection in remanence. NANOSCALE 2018; 10:10213-10220. [PMID: 29789851 DOI: 10.1039/c8nr02250j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Remanent spin injection into a spin light emitting diode (spin-LED) at zero magnetic field is a prerequisite for future application of spin optoelectronics. Here, we demonstrate the remanent spin injection into GaAs based LEDs with a thermally stable Mo/CoFeB/MgO spin injector. A systematic study of magnetic properties, polarization-resolved electroluminescence (EL) and atomic-scale interfacial structures has been performed in comparison with the Ta/CoFeB/MgO spin injector. The perpendicular magnetic anisotropy (PMA) of the Mo/CoFeB/MgO injector shows more advanced thermal stability than that of the Ta/CoFeB/MgO injector and robust PMA can be maintained up to 400 °C annealing. The remanent circular polarization (PC) of EL from the Mo capped spin-LED reaches a maximum value of 10% after 300 °C annealing, and even remains at 4% after 400 °C annealing. In contrast, the Ta capped spin-LED almost completely loses the remanent PC under 400 °C annealing. Combined advanced electron microscopy and spectroscopy studies reveal that a large amount of Ta diffuses into the MgO tunneling barrier through the CoFeB layer after 400 °C annealing. However, the diffusion of Mo into CoFeB is limited and never reaches the MgO barrier. These findings afford a comprehensive perspective to use the highly thermally stable Mo/CoFeB/MgO spin injector for efficient electrical spin injection in remanence.
Collapse
Affiliation(s)
- Bingshan Tao
- Institut Jean Lamour, UMR 7198, CNRS-Université de Lorraine, Campus ARTEM, 2 Allée André Guinier, BP 50840, 54011 Nancy, France.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Yu JX, Zang J. Giant perpendicular magnetic anisotropy in Fe/III-V nitride thin films. SCIENCE ADVANCES 2018; 4:eaar7814. [PMID: 29670948 PMCID: PMC5903905 DOI: 10.1126/sciadv.aar7814] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 02/13/2018] [Indexed: 06/08/2023]
Abstract
Large perpendicular magnetic anisotropy (PMA) in transition metal thin films provides a pathway for enabling the intriguing physics of nanomagnetism and developing broad spintronics applications. After decades of searches for promising materials, the energy scale of PMA of transition metal thin films, unfortunately, remains only about 1 meV. This limitation has become a major bottleneck in the development of ultradense storage and memory devices. We discovered unprecedented PMA in Fe thin-film growth on the [Formula: see text] N-terminated surface of III-V nitrides from first-principles calculations. PMA ranges from 24.1 meV/u.c. in Fe/BN to 53.7 meV/u.c. in Fe/InN. Symmetry-protected degeneracy between x2 - y2 and xy orbitals and its lift by the spin-orbit coupling play a dominant role. As a consequence, PMA in Fe/III-V nitride thin films is dominated by first-order perturbation of the spin-orbit coupling, instead of second-order in conventional transition metal/oxide thin films. This game-changing scenario would also open a new field of magnetism on transition metal/nitride interfaces.
Collapse
|
15
|
Current-induced magnetization switching in atom-thick tungsten engineered perpendicular magnetic tunnel junctions with large tunnel magnetoresistance. Nat Commun 2018; 9:671. [PMID: 29445186 PMCID: PMC5813193 DOI: 10.1038/s41467-018-03140-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Accepted: 01/19/2018] [Indexed: 11/29/2022] Open
Abstract
Perpendicular magnetic tunnel junctions based on MgO/CoFeB structures are of particular interest for magnetic random-access memories because of their excellent thermal stability, scaling potential, and power dissipation. However, the major challenge of current-induced switching in the nanopillars with both a large tunnel magnetoresistance ratio and a low junction resistance is still to be met. Here, we report spin transfer torque switching in nano-scale perpendicular magnetic tunnel junctions with a magnetoresistance ratio up to 249% and a resistance area product as low as 7.0 Ω µm2, which consists of atom-thick W layers and double MgO/CoFeB interfaces. The efficient resonant tunnelling transmission induced by the atom-thick W layers could contribute to the larger magnetoresistance ratio than conventional structures with Ta layers, in addition to the robustness of W layers against high-temperature diffusion during annealing. The critical switching current density could be lower than 3.0 MA cm−2 for devices with a 45-nm radius. Perpendicular magnetic tunnel junctions with large tunnel magnetoresistance and low junction resistance are promising for the magnetic random access memories. Here the authors achieve the spin-transfer-torque switching in perpendicular magnetic tunnel junctions with 249% tunnel magnetoresistance and low resistance-area product.
Collapse
|
16
|
Kuświk P, Głowiński H, Coy E, Dubowik J, Stobiecki F. Perpendicularly magnetized Co 20Fe 60B 20 layer sandwiched between Au with low Gilbert damping. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:435803. [PMID: 28762955 DOI: 10.1088/1361-648x/aa834d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Nowadays, the CoFeB thin layered film is intensively studied because of its potential applications in spintronic devices, especially devices based on spin-transfer torque phenomena. Hitherto, it has been shown that CoFeB may possess perpendicular magnetic anisotropy (PMA) when it is sandwiched between different layers (e.g. MgO, Pt, Pd, Ta, W). However, there is no experimental evidence that CoFeB, sandwiched between Au layers, has strong PMA. Moreover, in comparison with other noble metals, Au-based film systems exhibit the smallest spin pumping effect, which provides the main contribution to the damping in thin films in contact with heavy metals. Therefore, Au/CoFeB/Au may be a good candidate for future applications, where perpendicular magnetic anisotropy and low damping are required. Here, we show that PMA and low damping can be achieved in a Au/CoFeB/Au system without annealing.
Collapse
Affiliation(s)
- Piotr Kuświk
- Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland
| | | | | | | | | |
Collapse
|
17
|
Luo Z, Lu Z, Xiong C, Zhu T, Wu W, Zhang Q, Wu H, Zhang X, Zhang X. Reconfigurable Magnetic Logic Combined with Nonvolatile Memory Writing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1605027. [PMID: 27862413 DOI: 10.1002/adma.201605027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 10/23/2016] [Indexed: 06/06/2023]
Abstract
In magnetic logic, four basic Boolean logic operations can be programmed by a magnetic bit at room temperature with a high output ratio (>103 %). In the same clock cycle, benefiting from the built-in spin Hall effect, logic results can be directly written into magnetic bits using an all-electric method.
Collapse
Affiliation(s)
- Zhaochu Luo
- Key Laboratory of Advanced Materials (MOE) and Beijing National Center for Electron Microscopy, Tsinghua University, Beijing, 100084, China
| | - Ziyao Lu
- Key Laboratory of Advanced Materials (MOE) and Beijing National Center for Electron Microscopy, Tsinghua University, Beijing, 100084, China
| | - Chengyue Xiong
- Key Laboratory of Advanced Materials (MOE) and Beijing National Center for Electron Microscopy, Tsinghua University, Beijing, 100084, China
| | - Tao Zhu
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100084, China
| | - Wei Wu
- Institute of Microelectronics, Tsinghua University, Beijing, 100084, China
| | - Qiang Zhang
- Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 239955, Kingdom of Saudi Arabia
| | - Huaqiang Wu
- Institute of Microelectronics, Tsinghua University, Beijing, 100084, China
| | - Xixiang Zhang
- Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 239955, Kingdom of Saudi Arabia
| | - Xiaozhong Zhang
- Key Laboratory of Advanced Materials (MOE) and Beijing National Center for Electron Microscopy, Tsinghua University, Beijing, 100084, China
| |
Collapse
|
18
|
Takemura Y, Lee DY, Lee SE, Park JG. Dependency of tunneling magnetoresistance ratio on Pt seed-layer thickness for double MgO perpendicular magnetic tunneling junction spin-valves with a top Co 2Fe 6B 2 free layer ex-situ annealed at 400 °C. NANOTECHNOLOGY 2016; 27:485203. [PMID: 27796272 DOI: 10.1088/0957-4484/27/48/485203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
For the double MgO based perpendicular magnetic tunneling junction (p-MTJ) spin-valves with a top Co2Fe6B2 free layer ex situ annealed at 400 °C, the tunneling-magnetoresistance ratio (TMR) strongly depended on the platinum (Pt) seed layer thickness (t Pt): it peaked (∼134%) at a specific t Pt (3.3 nm). The TMR ratio was initially and slightly increased from 113%-134% by the enhancement of the magnetic moment of the Co2Fe6B2 pinned layer when t Pt increased from 2.0-3.3 nm, and then rapidly decreased from 134%-38.6% by the degrading face-centered-cubic crystallinity of the MgO tunneling barrier when t Pt increased from 3.3-14.3 nm.
Collapse
Affiliation(s)
- Yasutaka Takemura
- MRAM Center, Department of Electronics and Computer Engineering, Hanyang University, Seoul, 04763, Korea. Epitaxial Engineering Department, SUMCO CORPORATION, 1007-62, Chitose-shi, Hokkaido 066-0051, Japan
| | | | | | | |
Collapse
|
19
|
Chen PJ, Iunin YL, Cheng SF, Shull RD. Underlayer Effect on Perpendicular Magnetic Anisotropy in Co 20Fe 60B 20\MgO Films. IEEE TRANSACTIONS ON MAGNETICS 2016; 52:4400504. [PMID: 27499549 PMCID: PMC4971582 DOI: 10.1109/tmag.2015.2511662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Perpendicular Magnetic Tunneling Junctions (pMTJs) with Ta\CoFeB\MgO have been extensively studied in recent years. However, the effects of the underlayer on the formation of the CoFeB perpendicular magnetic anisotropy (PMA) are still not well understood. Here we report the results of our systematic use of a wide range of elements (Ti, V, Cr, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt and Au) encompassed by columns IVA, VA, VIA, VIIA and VIIIA of the periodic table as the underlayer in a underlayer\Co20Fe60B20\MgO stack. Our goals were to survey more elements which could conceivably create a PMA in CoFeB and thereby to explore the mechanisms enabling these underlayers to enhance or create the PMA. We found underlayer elements having both an outer shell of 4d electrons (Zr, Nb Mo, and Pd) and 5d electrons (Hf, Ta, W, Re, Ir, and Pt) resulted in the development of a PMA in the MgO-capped Co20Fe60B20. Hybridization between the 3d electrons of the Fe or Co (in the Co20Fe60B20) at the interface with the 4d or 5d electrons of the underlayer is thought to be the cause of the PMA development.
Collapse
Affiliation(s)
- P J Chen
- National Institute of Standards of Technology, Gaithersburg, MD, 20899, USA
| | - Y L Iunin
- National Institute of Standards of Technology, Gaithersburg, MD, 20899, USA; Institute of Solid State Physics, RAS, Chernogolovka, Moscow distr., 142432 Russia
| | - S F Cheng
- Naval Research Laboratory, Washington, DC 20375, USA
| | - R D Shull
- National Institute of Standards of Technology, Gaithersburg, MD, 20899, USA
| |
Collapse
|
20
|
Luo Z, Xiong C, Zhang X, Guo ZG, Cai J, Zhang X. Extremely Large Magnetoresistance at Low Magnetic Field by Coupling the Nonlinear Transport Effect and the Anomalous Hall Effect. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:2760-2764. [PMID: 26857904 DOI: 10.1002/adma.201504023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/10/2015] [Indexed: 06/05/2023]
Abstract
The anomalous Hall effect of a magnetic material is coupled to the nonlinear transport effect of a semiconductor material in a simple structure to achieve a large geometric magnetoresistance (MR) based on a diode-assisted mechanism. An extremely large MR (>10(4) %) at low magnetic fields (1 mT) is observed at room temperature. This MR device shows potential for use as a logic gate for the four basic Boolean logic operations.
Collapse
Affiliation(s)
- Zhaochu Luo
- School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, P. R. China
- Beijing National Center for Electron Microscopy, Tsinghua University, Beijing, 100084, P. R. China
| | - Chengyue Xiong
- School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, P. R. China
- Beijing National Center for Electron Microscopy, Tsinghua University, Beijing, 100084, P. R. China
| | - Xu Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100084, P. R. China
| | - Zhen-Gang Guo
- School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, P. R. China
- Beijing National Center for Electron Microscopy, Tsinghua University, Beijing, 100084, P. R. China
| | - Jianwang Cai
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100084, P. R. China
| | - Xiaozhong Zhang
- School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, P. R. China
- Beijing National Center for Electron Microscopy, Tsinghua University, Beijing, 100084, P. R. China
| |
Collapse
|
21
|
Peng S, Wang M, Yang H, Zeng L, Nan J, Zhou J, Zhang Y, Hallal A, Chshiev M, Wang KL, Zhang Q, Zhao W. Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structures. Sci Rep 2015; 5:18173. [PMID: 26656721 PMCID: PMC4676065 DOI: 10.1038/srep18173] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 11/13/2015] [Indexed: 11/09/2022] Open
Abstract
Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts extensive attentions due to its non-volatility, high density and low power consumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel junction (MTJ), which possesses a high tunnel magnetoresistance ratio as well as a large value of perpendicular magnetic anisotropy (PMA). It has been experimentally proven that a capping layer coating on CoFeB layer is essential to obtain a strong PMA. However, the physical mechanism of such effect remains unclear. In this paper, we investigate the origin of the PMA in MgO/CoFe/metallic capping layer structures by using a first-principles computation scheme. The trend of PMA variation with different capping materials agrees well with experimental results. We find that interfacial PMA in the three-layer structures comes from both the MgO/CoFe and CoFe/capping layer interfaces, which can be analyzed separately. Furthermore, the PMAs in the CoFe/capping layer interfaces are analyzed through resolving the magnetic anisotropy energy by layer and orbital. The variation of PMA with different capping materials is attributed to the different hybridizations of both d and p orbitals via spin-orbit coupling. This work can significantly benefit the research and development of nanoscale STT-MRAM.
Collapse
Affiliation(s)
- Shouzhong Peng
- Fert Beijing Institute, Beihang University, Beijing 100191, China.,School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
| | - Mengxing Wang
- Fert Beijing Institute, Beihang University, Beijing 100191, China.,School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
| | - Hongxin Yang
- Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble, France; CEA, INAC-SPINTEC, F-38000 Grenoble, France and CNRS, SPINTEC, F-38000 Grenoble, France
| | - Lang Zeng
- Fert Beijing Institute, Beihang University, Beijing 100191, China.,School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
| | - Jiang Nan
- Fert Beijing Institute, Beihang University, Beijing 100191, China.,School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
| | - Jiaqi Zhou
- Fert Beijing Institute, Beihang University, Beijing 100191, China.,School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
| | - Youguang Zhang
- Fert Beijing Institute, Beihang University, Beijing 100191, China.,School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
| | - Ali Hallal
- Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble, France; CEA, INAC-SPINTEC, F-38000 Grenoble, France and CNRS, SPINTEC, F-38000 Grenoble, France
| | - Mairbek Chshiev
- Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble, France; CEA, INAC-SPINTEC, F-38000 Grenoble, France and CNRS, SPINTEC, F-38000 Grenoble, France
| | - Kang L Wang
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Qianfan Zhang
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Weisheng Zhao
- Fert Beijing Institute, Beihang University, Beijing 100191, China.,School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
| |
Collapse
|
22
|
Liu Y, Zhang J, Wang S, Jiang S, Liu Q, Li X, Wu Z, Yu G. Ru Catalyst-Induced Perpendicular Magnetic Anisotropy in MgO/CoFeB/Ta/MgO Multilayered Films. ACS APPLIED MATERIALS & INTERFACES 2015; 7:26643-26648. [PMID: 26565747 DOI: 10.1021/acsami.5b08385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The high oxygen storage/release capability of the catalyst Ru is used to manipulate the interfacial electronic structure in spintronic materials to obtain perpendicular magnetic anisotropy (PMA). Insertion of an ultrathin Ru layer between the CoFeB and Ta layers in MgO/CoFeB/Ta/MgO films effectively induces PMA without annealing. Ru plays a catalytic role in Fe-O-Ta bonding and isolation at the metal-oxide interface to achieve moderate interface oxidation. In contrast, PMA cannot be obtained in the sample with a Mg insertion layer or without an insertion layer because of the lack of a catalyst. Our work would provide a new approach toward catalyst-induced PMA for future CoFeB-based spintronic device applications.
Collapse
Affiliation(s)
- Yiwei Liu
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Jingyan Zhang
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Shouguo Wang
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Shaolong Jiang
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Qianqian Liu
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Xujing Li
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Zhenglong Wu
- Analytical and Testing Center, Beijing Normal University , Beijing 100875, China
| | - Guanghua Yu
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| |
Collapse
|
23
|
Kim JH, Lee JB, An GG, Yang SM, Chung WS, Park HS, Hong JP. Ultrathin W space layer-enabled thermal stability enhancement in a perpendicular MgO/CoFeB/W/CoFeB/MgO recording frame. Sci Rep 2015; 5:16903. [PMID: 26584638 PMCID: PMC4653616 DOI: 10.1038/srep16903] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 10/21/2015] [Indexed: 11/21/2022] Open
Abstract
Perpendicularly magnetized tunnel junctions (p-MTJs) show promise as reliable candidates for next-generation memory due to their outstanding features. However, several key challenges remain that affect CoFeB/MgO-based p-MTJ performance. One significant issue is the low thermal stability (Δ) due to the rapid perpendicular magnetic anisotropy (PMA) degradation during annealing at temperatures greater than 300 °C. Thus, the ability to provide thermally robust PMA characteristics is a key steps towards extending the use of these materials. Here, we examine the influence of a W spacer on double MgO/CoFeB/W/CoFeB/MgO frames as a generic alternative layer to ensure thermally-robust PMAs at temperatures up to 425 °C. The thickness-dependent magnetic features of the W layer were evaluated at various annealing temperatures to confirm the presence of strong ferromagnetic interlayer coupling at an optimized 0.55 nm W spacer thickness. Using this W layer we achieved a higher Δ of 78 for an approximately circular 20 nm diameter free layer device.
Collapse
Affiliation(s)
- Jae-Hong Kim
- Division of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul 133-791, South Korea
| | - Ja-Bin Lee
- Reserach Institute for Convergence of Basic Science, Novel Functional Materials and Devices Lab, Department of Physics, Hanyang University, Seoul 133-791, South Korea
| | - Gwang-Guk An
- Reserach Institute for Convergence of Basic Science, Novel Functional Materials and Devices Lab, Department of Physics, Hanyang University, Seoul 133-791, South Korea
| | - Seung-Mo Yang
- Reserach Institute for Convergence of Basic Science, Novel Functional Materials and Devices Lab, Department of Physics, Hanyang University, Seoul 133-791, South Korea
| | - Woo-Seong Chung
- Nano Quantum Electronics Lab, Department of Electronics and Computer Engineering, Hanyang University, Seoul 133-791, South Korea
| | - Hae-Soo Park
- Reserach Institute for Convergence of Basic Science, Novel Functional Materials and Devices Lab, Department of Physics, Hanyang University, Seoul 133-791, South Korea
| | - Jin-Pyo Hong
- Division of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul 133-791, South Korea.,Reserach Institute for Convergence of Basic Science, Novel Functional Materials and Devices Lab, Department of Physics, Hanyang University, Seoul 133-791, South Korea
| |
Collapse
|
24
|
Tunnel Junction with Perpendicular Magnetic Anisotropy: Status and Challenges. MICROMACHINES 2015. [DOI: 10.3390/mi6081023] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|