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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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.
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Pandey L, Husain S, Barwal V, Hait S, Gupta NK, Mishra V, Kumar N, Sharma N, Dixit D, Singh V, Chaudhary S. Topological transport properties of highly oriented Bi 2Te 3thin film deposited by sputtering. J Phys Condens Matter 2023; 35:355702. [PMID: 37172602 DOI: 10.1088/1361-648x/acd50a] [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] [Received: 01/04/2023] [Accepted: 05/12/2023] [Indexed: 05/15/2023]
Abstract
Topological insulators (TIs) are the promising materials for next-generation technology due to their exotic features such as spin momentum locking, conducting surface states, etc. However, the high-quality growth of TIs by sputtering technique, which is one of the foremost industrial requirements, is extremely challenging. Also, the demonstration of simple investigation protocols to characterize topological properties of TIs using electron-transport methods is highly desirable. Here, we report the quantitative investigation of non-trivial parameters employing magnetotransport measurements on a prototypical highly textured Bi2Te3TI thin film prepared by sputtering. Through the systematic analyses of the temperature and magnetic field dependent resistivity, all topological parameters associated with TIs, such as coherency factorα, Berry phase (ΦB), mass term (m), the dephasing parameter (p), slope of temperature dependent conductivity correction (κ) and the surface state penetration depth (λ) are estimated by using the modified 'Hikami-Larkin-Nagaoka', 'Lu-Shen' and 'Altshuler-Aronov' models. The obtained values of topological parameters are well comparable to those reported on molecular beam epitaxy grown TIs. The epitaxial growth of Bi2Te3film using sputtering, and investigation of the non-trivial topological states from its electron-transport behavior are important for their fundamental understanding and technological applications.
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Affiliation(s)
- Lalit Pandey
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Sajid Husain
- 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
| | - Soumyarup Hait
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Nanhe Kumar Gupta
- 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
| | - Nakul Kumar
- 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
| | - Dinesh Dixit
- Central Research Facility, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Veer Singh
- Central Research Facility, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Sujeet Chaudhary
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India
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Mishra V, Kumar A, Pandey L, Gupta NK, Hait S, Barwal V, Sharma N, Kumar N, Chandra S, Chaudhary S. Disordered spin gapless semiconducting CoFeCrGa Heusler alloy thin films on Si (100): experiment and theory. Nanoscale 2022; 15:337-349. [PMID: 36503983 DOI: 10.1039/d2nr03424g] [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: 06/17/2023]
Abstract
Spin gapless semiconductors (SGSs) are an intriguing class of quantum materials that bridge the gap between half-metallic ferromagnets and semiconductors. The presence of a semiconducting bandgap for one spin channel and zero band gap for other spin channels, together with the possibility of four different band structure configurations, makes them one of the most desirable candidates to be used in tunable spin transport based spintronics devices. Here, we have performed various structural, magnetic and transport measurements on an optimized CoFeCrGa (CFCG) Heusler alloy thin film (∼50 nm) grown over a Si(100) substrate using an industry-viable magnetron sputtering technique. The grown film showed B2-ordering under the given set of X-ray diffraction measurement conditions with a saturation magnetization (Ms) of 1.86μB per f.u. (at 5 K) and a Curie temperature of ∼595 K. Nearly linearly varying longitudinal resistivity with a negative temperature coefficient was observed. A fitted longitudinal conductivity curve through a "two-carrier model" shows a slight band overlap in the gapless channel for one spin channel and a small energy gap (ΔE) of 167 meV for other spin channels. A negative and linear out-of-plane magnetoresistance response was observed in these films. The temperature dependent anomalous Hall effect measurement gives nearly temperature independent carrier concentration (and/or) mobility with an anomalous Hall conductivity of 91.35 S cm-1 at 5 K. The first principles calculations have also been performed for bulk and (220) CFCG surfaces to correlate the various structural, electronics and magnetic properties of the optimized CFCG Heusler alloy thin film. The DFT derived results, viz. lattice parameter and MS exhibit a good match with the experimentally observed results. All these properties collectively imply that the grown film possesses disordered-SGS like behaviour. It is remarkable to note that CFCG films with the (022) surface possess a very high electronic spin polarization of 91%. The results of the study suggest that CFCG is a potential candidate to be used in spintronics-based devices such as spin-injectors.
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Affiliation(s)
- Vireshwar Mishra
- 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.
| | - Nanhe Kumar Gupta
- 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.
| | - 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.
| | - Sharat Chandra
- Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, Tamilnadu-603102, India
| | - Sujeet Chaudhary
- Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, 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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Masarrat A, Bhogra A, Meena R, Bala M, Singh R, Barwal V, Dong CL, Chen CL, Som T, Kumar A, Niazi A, Asokan K. Effect of Fe ion implantation on the thermoelectric properties and electronic structures of CoSb3 thin films. RSC Adv 2019; 9:36113-36122. [PMID: 35540568 PMCID: PMC9074955 DOI: 10.1039/c9ra06873b] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [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: 08/29/2019] [Accepted: 10/14/2019] [Indexed: 11/21/2022] Open
Abstract
In the present study, thin films of single-phase CoSb3 were deposited onto Si(100) substrates via pulsed laser deposition (PLD) method using a polycrystalline target of CoSb3. These films were implanted by 120 keV Fe-ions with three different fluences: 1 × 1015, 2.5 × 1015 and 5 × 1015 ions per cm2. All films were characterised by X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), Rutherford backscattering (RBS) spectrometry and X-ray absorption spectroscopy (XAS). XRD data revealed that the ion implantation decreased the crystalline nature of these films, which are recovered after the rapid thermal annealing process. The Seebeck coefficient S vary with the fluences in the temperature range of 300 K to 420 K, and is found to be highest (i.e., 254 μV K−1) at 420 K for the film implanted with 1 × 1015 ions per cm2. The high S and low resistivity lead to the highest power factor for the film implanted with 1 × 1015 ions per cm2 (i.e., 700 μW m−1 K−2) at 420 K. The changing of the sign of S from negative for the pristine film to positive for the Fe-implanted samples confirm that the Fe ions are electrically active and act as electron acceptors by replacing the Co atoms. XAS measurements confirm that the Fe ions occupied the Co site in the cubic frame of the skutterudite and exist in the 3+ oxidation state in this structure. The power factor for the Fe ion-implanted samples is greater than that of the pristine sample with a value of 700 mW m−1 K−2 at 420 K for the I1E15A sample.![]()
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Affiliation(s)
- Anha Masarrat
- Inter University Accelerator Centre
- New Delhi-110067
- India
- Department of Physics
- Jamia Millia Islamia
| | | | | | - Manju Bala
- Department of Physics & Astrophysics
- University of Delhi
- New Delhi-110007
- India
| | | | - Vineet Barwal
- Department of Physics
- Indian Institute of Technology Delhi
- New Delhi-110016
- India
| | - Chung-Li Dong
- Research Center for X-ray Science
- Department of Physics
- Tamkang University
- Taiwan
| | - Chi-Liang Chen
- National Synchrotron Radiation Research Centre
- Hsinchu
- Taiwan
| | - T. Som
- Institute of Physics
- Bhubaneswar-751005
- India
| | - Ashish Kumar
- Inter University Accelerator Centre
- New Delhi-110067
- India
| | - A. Niazi
- Department of Physics
- Jamia Millia Islamia
- New Delhi-110025
- India
| | - K. Asokan
- Inter University Accelerator Centre
- New Delhi-110067
- India
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