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Khan KIA, Kumar A, Gupta P, Yadav RS, Åkerman J, Muduli PK. Magnetodynamic properties of ultrathin films of Fe[Formula: see text]Sn[Formula: see text]-a topological kagome ferromagnet. Sci Rep 2024; 14:3487. [PMID: 38347066 DOI: 10.1038/s41598-024-53621-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 02/02/2024] [Indexed: 02/18/2024] Open
Abstract
Fe[Formula: see text]Sn[Formula: see text] is a topological kagome ferromagnet that possesses numerous Weyl points close to the Fermi energy, which can manifest various unique transport phenomena such as chiral anomaly, anomalous Hall effect, and giant magnetoresistance. However, the magnetodynamic properties of Fe[Formula: see text]Sn[Formula: see text] have not yet been explored. Here, we report, for the first time, the measurements of the intrinsic Gilbert damping constant ([Formula: see text]), and the effective spin mixing conductance (g[Formula: see text]) of Pt/Fe[Formula: see text]Sn[Formula: see text] bilayers for Fe[Formula: see text]Sn[Formula: see text] thicknesses down to 2 nm, for which [Formula: see text] is [Formula: see text], and g[Formula: see text] is [Formula: see text]. The films have a high saturation magnetization, [Formula: see text], and large anomalous Hall coefficient, [Formula: see text]. The large values of g[Formula: see text], together with the topological properties of Fe[Formula: see text]Sn[Formula: see text], make Fe[Formula: see text]Sn[Formula: see text]/Pt bilayers useful heterostructures for the study of topological spintronic devices.
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Affiliation(s)
- Kacho Imtiyaz Ali Khan
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India
| | - Akash Kumar
- Applied Spintronics Group, Department of Physics, University of Gothenburg, Gothenburg, 412 96, 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
| | - Pankhuri Gupta
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India
| | - Ram Singh Yadav
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India
| | - Johan Åkerman
- Applied Spintronics Group, Department of Physics, University of Gothenburg, Gothenburg, 412 96, 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.
| | - Pranaba Kishor Muduli
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
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Mudgal R, Jakhar A, Gupta P, Yadav RS, Biswal B, Sahu P, Bangar H, Kumar A, Chowdhury N, Satpati B, Kumar Nanda BR, Satpathy S, Das S, Muduli PK. Magnetic-Proximity-Induced Efficient Charge-to-Spin Conversion in Large-Area PtSe 2/Ni 80Fe 20 Heterostructures. Nano Lett 2023; 23:11925-11931. [PMID: 38088819 DOI: 10.1021/acs.nanolett.3c04060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
As a topological Dirac semimetal with controllable spin-orbit coupling and conductivity, PtSe2, a transition-metal dichalcogenide, is a promising material for several applications, from optoelectrics to sensors. However, its potential for spintronics applications has yet to be explored. In this work, we demonstrate that the PtSe2/Ni80Fe20 heterostructure can generate large damping-like current-induced spin-orbit torques (SOT), despite the absence of spin-splitting in bulk PtSe2. The efficiency of charge-to-spin conversion is found to be -0.1 ± 0.02 nm-1 in PtSe2/Ni80Fe20, which is 3 times that of the control sample, Ni80Fe20/Pt. Our band structure calculations show that the SOT due to PtSe2 arises from an unexpectedly large spin splitting in the interfacial region of PtSe2 introduced by the proximity magnetic field of the Ni80Fe20 layer. Our results open up the possibilities of using large-area PtSe2 for energy-efficient nanoscale devices by utilizing proximity-induced SOT.
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Affiliation(s)
- Richa Mudgal
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Alka Jakhar
- Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Pankhuri Gupta
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Ram Singh Yadav
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Bubunu Biswal
- Condensed Matter Theory and Computational Lab, Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
- Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai 600036, India
| | - Pratik Sahu
- Condensed Matter Theory and Computational Lab, Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
- Department of Physics & Astronomy, University of Missouri, Columbia, Missouri 65211, United States
| | - Himanshu Bangar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Akash Kumar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
- Department of Physics, University of Gothenburg, Gothenburg 412 96, Sweden
| | - Niru Chowdhury
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Biswarup Satpati
- Surface Physics & Material Science Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata 700064, India
| | - Birabar Ranjit Kumar Nanda
- Condensed Matter Theory and Computational Lab, Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
- Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sashi Satpathy
- Condensed Matter Theory and Computational Lab, Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
- Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai 600036, India
- Department of Physics & Astronomy, University of Missouri, Columbia, Missouri 65211, United States
| | - Samaresh Das
- Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Pranaba Kishor Muduli
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Dewan S, Khanikar PD, Mudgal R, Singh A, Muduli PK, Singh R, Das S. Large-Area GeSe Realized Using Pulsed Laser Deposition for Ultralow-Noise and Ultrafast Broadband Phototransistors. ACS Appl Mater Interfaces 2023. [PMID: 37216628 DOI: 10.1021/acsami.3c02522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Here, we report on the comprehensive growth, characterization, and optoelectronic application of large-area, two-dimensional germanium selenide (GeSe) layers prepared using the pulsed laser deposition (PLD) technique. Back-gated phototransistors based on few-layered 2D GeSe have been fabricated on a SiO2/Si substrate for ultrafast, low noise, and broadband light detection, showing spectral functionalities over a broad wavelength range of 0.4-1.5 μm. The broadband detection capabilities of the device have been attributed to the self-assembled GeOx/GeSe heterostructure and sub-bandgap absorption in GeSe. Besides a high photoresponsivity of 25 AW-1, the GeSe phototransistor displayed a high external quantum efficiency of the order of 6.14 × 103%, a maximum specific detectivity of 4.16 × 1010 Jones, and an ultralow noise equivalent power of 0.09 pW/Hz1/2. The detector has an ultrafast response/recovery time of 3.2/14.9 μs and can show photoresponse up to a high cut-off frequency of 150 kHz. These promising device parameters exhibited by PLD-grown GeSe layers-based detectors make it a favorable choice against present-day mainstream van der Waals semiconductors with limited scalability and optoelectronic compatibility in the visible-to-infrared spectral range.
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Affiliation(s)
- Sheetal Dewan
- School of Interdisciplinary Research, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Prabal Dweep Khanikar
- University of Queensland-IIT Delhi Academy of Research (UQIDAR), Hauz Khas, New Delhi 110016, India
- Centre for Applied Research in Electronics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Richa Mudgal
- Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Avneet Singh
- Department of Physics, Shivaji College, University of Delhi, New Delhi 110027, India
| | - Pranaba Kishor Muduli
- Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Rajendra Singh
- Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India
- Department of Electrical Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Samaresh Das
- Centre for Applied Research in Electronics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
- Department of Electrical Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India
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Bangar H, Kumar A, Chowdhury N, Mudgal R, Gupta P, Yadav RS, Das S, Muduli PK. Large Spin-To-Charge Conversion at the Two-Dimensional Interface of Transition-Metal Dichalcogenides and Permalloy. ACS Appl Mater Interfaces 2022; 14:41598-41604. [PMID: 36052925 DOI: 10.1021/acsami.2c11162] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Spin-to-charge conversion is an essential requirement for the implementation of spintronic devices. Recently, monolayers (MLs) of semiconducting transition-metal dichalcogenides (TMDs) have attracted considerable interest for spin-to-charge conversion due to their high spin-orbit coupling and lack of inversion symmetry in their crystal structure. However, reports of direct measurement of spin-to-charge conversion at TMD-based interfaces are very much limited. Here, we report on the room-temperature observation of a large spin-to-charge conversion arising from the interface of Ni80Fe20 (Py) and four distinct large-area (∼5 × 2 mm2) ML TMDs, namely, MoS2, MoSe2, WS2, and WSe2. We show that both spin mixing conductance and the Rashba efficiency parameter (λIREE) scale with the spin-orbit coupling strength of the ML TMD layers. The λIREE parameter is found to range between -0.54 and -0.76 nm for the four ML TMDs, demonstrating a large spin-to-charge conversion. Our findings reveal that the TMD/ferromagnet interface can be used for efficient generation and detection of spin current, opening new opportunities for novel spintronic devices.
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Affiliation(s)
- Himanshu Bangar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Akash Kumar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
- Department of Physics, University of Gothenburg, Gothenburg 412 96, Sweden
| | - Niru Chowdhury
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Richa Mudgal
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Pankhuri Gupta
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Ram Singh Yadav
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Samaresh Das
- Center for Applied Research in Electronics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Pranaba Kishor Muduli
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Hait S, Husain S, Bangar H, Pandey L, Barwal V, Kumar N, Gupta NK, Mishra V, Sharma N, Gupta P, Yadav BS, Muduli PK, Chaudhary S. Spin Pumping through Different Spin-Orbit Coupling Interfaces in β-W/Interlayer/Co 2FeAl Heterostructures. ACS Appl Mater Interfaces 2022; 14:37182-37191. [PMID: 35921689 DOI: 10.1021/acsami.2c09941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Spin pumping has been considered a powerful tool to manipulate the spin current in a ferromagnetic/nonmagnetic (FM/NM) system, where the NM part exhibits large spin-orbit coupling (SOC). In this work, the spin pumping in β-W/Interlayer (IL)/Co2FeAl (CFA) heterostructures grown on Si(100) is systematically investigated with different ILs in which SOC strength ranges from weak to strong. We first measure the spin pumping through the enhancement of effective damping in CFA by varying the thickness of β-W. The damping enhancement in the bilayer of β-W/CFA (without IL) is found to be ∼50% larger than the Gilbert damping in a single CFA layer with a spin diffusion length and spin mixing conductance of 2.12 ± 0.27 nm and 13.17 ± 0.34 nm-2, respectively. Further, the ILs of different SOC strengths such as Al, Mg, Mo, and Ta were inserted at the β-W/CFA interface to probe their impact on damping in β-W/ILs/CFA. The effective damping reduced to 8% and 20% for Al and Mg, respectively, whereas it increased to 66% and 75% with ILs of Mo and Ta, respectively, compared to the β-W/CFA heterostructure. Thus, in the presence of ILs with weak SOC, the spin pumping at the β-W/CFA interface is suppressed, while for the high SOC ILs effective damping increased significantly from its original value of β-W/CFA bilayer using a thin IL. This is further confirmed by performing inverse spin Hall effect measurements. In summary, the transfer of spin angular momentum can be significantly enhanced by choosing a proper ultrathin interface layer. Our study provides a tool to increase the spin current production by inserting an appropriate thin interlayer which is useful in modifying the heterostructure for efficient performance in spintronics devices.
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Affiliation(s)
- Soumyarup Hait
- Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Sajid Husain
- Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Himanshu Bangar
- Spin Dynamics Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Lalit Pandey
- Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Vineet Barwal
- Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Nakul Kumar
- Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Nanhe Kumar Gupta
- Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Vireshwar Mishra
- Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Nikita Sharma
- Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Pankhuri Gupta
- Spin Dynamics Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Brajesh S Yadav
- Solid State Physics Laboratory, Lucknow Road, Timarpur, Delhi 110054, India
| | - Pranaba Kishor Muduli
- Spin Dynamics Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Sujeet Chaudhary
- Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India
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Khan KIA, Yadav RS, Bangar H, Kumar A, Chowdhury N, Muduli PK, Muduli PK. Intrinsic anomalous Hall effect in thin films of topological kagome ferromagnet Fe 3Sn 2. Nanoscale 2022; 14:8484-8492. [PMID: 35662312 DOI: 10.1039/d2nr00443g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Fe3Sn2, a kagome ferromagnet, is a potential quantum material with intriguing topological features. Despite substantial experimental work on the bulk single crystals, the thin film growth of Fe3Sn2 remains relatively unexplored. Here, we investigate the effect of two different seed layers (Ta and Pt) on the growth of Fe3Sn2 thin films. We demonstrate the growth of polycrystalline Fe3Sn2 thin films on Si/SiO2 substrates by room temperature sputter deposition, followed by in situ annealing at 500 °C. Our structural and magnetic measurements indicate that a pure ferromagnetic phase is formed for the Pt/Fe3Sn2 thin films with higher saturation magnetization of Ms = 464 emu cc-1, while a mixed-phase (consisting of ferromagnetic, Fe3Sn2 and antiferromagnetic, FeSn) is formed for the Ta/Fe3Sn2 thin films with a lower Ms of 240 emu cc-1. The Pt/Fe3Sn2 thin films also exhibit an anomalous Hall coefficient, Rs ≈ 2.6 × 10-10 Ω cm-1 G-1 at room temperature, which is two order of magnitude higher compared to 3d-transition metal ferromagnets. A non-zero temperature-independent anomalous Hall conductivity σintxy = (23 ± 11) Ω-1 cm-1 indicates an intrinsic mechanism of anomalous Hall effect originating from Berry curvature. These results are important for realizing novel topological spintronic devices on a CMOS-compatible substrate.
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Affiliation(s)
- Kacho Imtiyaz Ali Khan
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Ram Singh Yadav
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Himanshu Bangar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Akash Kumar
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Niru Chowdhury
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Prasanta Kumar Muduli
- Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036, India
| | - Pranaba Kishor Muduli
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
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Sharma R, Sisodia N, Iacocca E, Awad AA, Åkerman J, Muduli PK. A high-speed single sideband generator using a magnetic tunnel junction spin torque nano-oscillator. Sci Rep 2017; 7:13422. [PMID: 29044190 PMCID: PMC5647387 DOI: 10.1038/s41598-017-13551-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/26/2017] [Indexed: 12/04/2022] Open
Abstract
An important property of spin-torque nano-oscillators (STNOs) is their ability to produce a frequency modulated (FM) signal, which is very critical for communication applications. We here demonstrate a novel single sideband (SSB) modulation phenomenon using a magnetic tunnel junction (MTJ)-based STNO, which saves transmission bandwidth and in principle should minimize attenuation for wireless communication. Experimentally, lower single sidebands (LSSBs) have been successfully demonstrated over a wide range of modulation frequency, f m = 150 MHz-1 GHz. The observed LSSBs are determined by the intrinsic properties of the device, which can be modeled well by a nonlinear frequency and amplitude modulation formulation and reproduced in macrospin simulations. Moreover, our macrospin simulation results show that the range of modulation current and modulation frequency for generating SSBs can be controlled by the field-like torque and biasing conditions.
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Affiliation(s)
- Raghav Sharma
- Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi, 110016, India.
| | - Naveen Sisodia
- Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi, 110016, India
| | - Ezio Iacocca
- Department of Physics, Division for Theoretical Physics, Chalmers University of Technology, 412 96, Gothenburg, Sweden
- Department of Applied Mathematics, University of Colorado, Boulder, Colorado, 80309, USA
| | - Ahmad A Awad
- Department of Physics, University of Gothenburg, 41296, Gothenburg, Sweden
| | - Johan Åkerman
- Department of Physics, University of Gothenburg, 41296, Gothenburg, Sweden
- Materials and Nanophysics, School of Engineering Sciences, KTH-Royal Institute of Technology, Electrum 229, 164 40, Kista, Sweden
| | - P K Muduli
- Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi, 110016, India.
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Muduli PK, Barzola-Quiquia J, Dusari S, Ballestar A, Bern F, Böhlmann W, Esquinazi P. Large local Hall effect in pin-hole dominated multigraphene spin-valves. Nanotechnology 2013; 24:015703. [PMID: 23221165 DOI: 10.1088/0957-4484/24/1/015703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report local and non-local measurements in pin-hole dominated mesoscopic multigraphene spin-valves. Local spin-valve measurements show spurious switching behavior in resistance during magnetic field sweeping similar to the signal observed due to spin injection into multigraphene. The switching behavior has been explained in terms of a local Hall effect due to a thickness irregularity of the tunnel barrier. The local Hall effect appears due to a large local magnetostatic field produced near the roughness in the AlO(x) tunnel barrier. In our samples the resistance change due to the local Hall effect remains negligibly small above 75 K. A strong local Hall effect might hinder spin injection into multigraphene, resulting in no spin signal in non-local measurements.
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Affiliation(s)
- P K Muduli
- Division of Superconductivity and Magnetism, Institut für Experimentelle Physik II, Universität Leipzig, Linnéstrasse 5, D-04103 Leipzig, Germany.
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Muduli PK, Heinonen OG, Akerman J. Decoherence and mode hopping in a magnetic tunnel junction based spin torque oscillator. Phys Rev Lett 2012; 108:207203. [PMID: 23003182 DOI: 10.1103/physrevlett.108.207203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Indexed: 06/01/2023]
Abstract
We discuss the coherence of magnetic oscillations in a magnetic tunnel junction based spin torque oscillator as a function of the external field angle. Time-frequency analysis shows mode hopping between distinct oscillator modes, which arises from linear and nonlinear couplings in the Landau-Lifshitz-Gilbert equation, analogous to mode hopping observed in semiconductor ring lasers. These couplings and, therefore, mode hopping are minimized near the current threshold for the antiparallel alignment of free-layer with reference layer magnetization. Away from the antiparallel alignment, mode hopping limits oscillator coherence.
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Affiliation(s)
- P K Muduli
- Physics Department, University of Gothenburg, 41296 Gothenburg, Sweden
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Muduli PK, Rice WC, He L, Collins BA, Chu YS, Tsui F. Study of magnetic anisotropy and magnetization reversal using the quadratic magnetooptical effect in epitaxial Co(x)Mn(y)Ge(z)(111) films. J Phys Condens Matter 2009; 21:296005. [PMID: 21828544 DOI: 10.1088/0953-8984/21/29/296005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Magnetic anisotropy, magnetization reversal and the magnetooptic Kerr effect in Co(x)Mn(y)Ge(z) have been studied over a range of compositions between 0 and 50 at.% of Ge and between 1 and 3 in the Co to Mn atomic ratio, including the Heusler alloy Co(2)MnGe. A strong quadratic magnetooptic Kerr effect has been observed within a narrow region of composition centered around the Co to Mn atomic ratio of 2, which has been used to probe and quantify the magnetic anisotropy and magnetization reversal of the system. The anisotropy is sixfold with a weak uniaxial component, and it exhibits sensitive dependence on composition, especially on the atomic ratio between Co and Mn. The magnetization reversal process is consistent with the single-domain Stoner-Wohlfarth model.
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Affiliation(s)
- P K Muduli
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599, USA
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