1
|
Behera N, Chaurasiya AK, González VH, Litvinenko A, Bainsla L, Kumar A, Khymyn R, Awad AA, Fulara H, Åkerman J. Ultra-Low Current 10 nm Spin Hall Nano-Oscillators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2305002. [PMID: 37990141 DOI: 10.1002/adma.202305002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 10/19/2023] [Indexed: 11/23/2023]
Abstract
Nano-constriction based spin Hall nano-oscillators (SHNOs) are at the forefront of spintronics research for emerging technological applications, such as oscillator-based neuromorphic computing and Ising Machines. However, their miniaturization to the sub-50 nm width regime results in poor scaling of the threshold current. Here, it shows that current shunting through the Si substrate is the origin of this problem and studies how different seed layers can mitigate it. It finds that an ultra-thin Al2 O3 seed layer and SiN (200 nm) coated p-Si substrates provide the best improvement, enabling us to scale down the SHNO width to a truly nanoscopic dimension of 10 nm, operating at threshold currents below 30 μ $\umu$ A. In addition, the combination of electrical insulation and high thermal conductivity of the Al2 O3 seed will offer the best conditions for large SHNO arrays, avoiding any significant temperature gradients within the array. The state-of-the-art ultra-low operational current SHNOs hence pave an energy-efficient route to scale oscillator-based computing to large dynamical neural networks of linear chains or 2D arrays.
Collapse
Affiliation(s)
- Nilamani Behera
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
| | | | - Victor H González
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
| | - Artem Litvinenko
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
| | - Lakhan Bainsla
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
- Department of Physics, Indian Institute of Technology Ropar, Roopnagar, 140001, India
| | - Akash Kumar
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Roman Khymyn
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
| | - Ahmad A Awad
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Himanshu Fulara
- Department of Physics, Indian Institute of Technology Roorkee, Roorkee, 247667, India
| | - Johan Åkerman
- Physics Department, University of Gothenburg, Gothenburg, 412 96, Sweden
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| |
Collapse
|
2
|
Kumar A, Fulara H, Khymyn R, Litvinenko A, Zahedinejad M, Rajabali M, Zhao X, Behera N, Houshang A, Awad AA, Åkerman J. Robust Mutual Synchronization in Long Spin Hall Nano-oscillator Chains. NANO LETTERS 2023. [PMID: 37450893 PMCID: PMC10375588 DOI: 10.1021/acs.nanolett.3c02036] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
Mutual synchronization of N serially connected spintronic nano-oscillators boosts their coherence by N and peak power by N2. Increasing the number of synchronized nano-oscillators in chains holds significance for improved signal quality and emerging applications such as oscillator based unconventional computing. We successfully fabricate spin Hall nano-oscillator chains with up to 50 serially connected nanoconstrictions using W/NiFe, W/CoFeB/MgO, and NiFe/Pt stacks. Our experiments demonstrate robust and complete mutual synchronization of 21 nanoconstrictions at an operating frequency of 10 GHz, achieving line widths <134 kHz and quality factors >79,000. As the number of mutually synchronized oscillators increases, we observe a quadratic increase in peak power, resulting in 400-fold higher peak power in long chains compared to individual nanoconstrictions. While chains longer than 21 nanoconstrictions also achieve complete mutual synchronization, it is less robust, and their signal quality does not improve significantly, as they tend to break into partially synchronized states.
Collapse
Affiliation(s)
- Akash Kumar
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Himanshu Fulara
- Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Roman Khymyn
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
| | - Artem Litvinenko
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
| | | | | | - Xiaotian Zhao
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
| | - Nilamani Behera
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
| | - Afshin Houshang
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
| | - Ahmad A Awad
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Johan Åkerman
- Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden
- Center for Science and Innovation in Spintronics, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| |
Collapse
|