Anjan Barman

S.N. Bose National Centre for Basic Sciences

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Saswati Barman

University of Engineering & Management

Y. Otani

The University of Tokyo

Samiran Choudhury

S.N. Bose National Centre for Basic Sciences

Jaivardhan Sinha

SRM Institute of Science and Technology

Bivas Rana

Adam Mickiewicz University in Poznań

Sucheta Mondal

Shiv Nadar University

Amrit Kumar Mondal

S.N. Bose National Centre for Basic Sciences

Sourav Sahoo

S.N. Bose National Centre for Basic Sciences

Maciej Krawczyk

Adam Mickiewicz University in Poznań

Sudip Majumder

S.N. Bose National Centre for Basic Sciences

Cooperative Institutions

S.N. Bose National Centre for Basic Sciences

Centre National de la Recherche Scientifique

Indian Association for the Cultivation of Science

Tohoku University

Commissariat à l'Énergie Atomique et aux Énergies Alternatives

The University of Tokyo

CEA Grenoble

Spintronics Research Network of Japan

Université Grenoble Alpes

Indian Institute of Technology Delhi

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Extrinsic Spin–Orbit Coupling-Induced Large Modulation of Gilbert Damping Coefficient in CoFeB Thin Film on the Graphene Stack with Different Defect Density

The Journal of Physical Chemistry C (2017)

Sumona Sinha Santanu Pan Samiran Choudhury Jaivardhan Sinha Anjan Barman

Control of Gilbert damping parameter is imperative for various spintronic and magnonic devices, and various schemes have been attempted to achieve that. We report a large tunability of Gilbert damping by varying the underlayer of CoFeB thin film from few-layer graphene (FLG) to graphite layer. We measured the ultrafast magnetization dynamics of CoFeB, FLG/CoFeB, and graphite/CoFeB by using time-resolved magneto-optical Kerr effect (TR-MOKE) magnetometry. While the magnetization precession frequency remained independent of the underlayer, a very large variation (∼200%) in the value of the Gilbert damping coefficient α is observed from FLG/CoFeB (α ≈ 0.035 ± 0.005) to graphite/CoFeB (α ≈ 0.008 ± 0.001). This large variation of the damping coefficient is understood in terms of the extrinsic spin–orbit interaction of FLG and graphite films, which is very large in FLG due to the presence of large amount of surface defects in it. A faster demagnetization time and fast relaxation time (τ1) were noted for graphite/CoFeB bilayer system than that of FLG/CoFeB. In general, we infer that interfacial spin physics is primarily governed by the growth of CoFeB layer from our bilayer systems. This finding suggests a new direction toward the control of precessional magnetization dynamics, leading to applications in miniaturized high-speed magnetic devices.

Magnetization dynamics

Magneto-optic Kerr effect

10.1021/acs.jpcc.7b02790

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Citations (9)

Observation of incoherent picosecond magnetisation dynamics in micron sized Ni81Fe19 elements by time resolved scanning Kerr effect microscopy

IEE Proceedings - Science Measurement and Technology (2003)

Anjan Barman A. Kundrotaitė R. J. Hicken M. Rahman V. V. Kruglyak

We have studied small amplitude magnetisation precession in a square Ni81Fe19 element by time resolved scanning Kerr effect microscopy. A single precessional mode was observed with a 1 μm diameter probe spot placed at the centre of the element. Using a coherent rotation model, the presence of a four-fold anisotropy of about 30 Oe was deduced. Time resolved images show that the dynamic magnetisation is initially nonuniform at the edges of the element, with the nonuniformity then extending towards the centre. The dynamic magnetisation is uniform at the centre of the element over the measurement time, justifying the use of the coherent rotation model in the analysis of the precession frequency.

Precession

Picosecond

Magnetization dynamics

Magneto-optic Kerr effect

10.1049/ip-smt:20030868

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Citations (10)

Pulse reverse plating for integrated magnetics on Si

Journal of Magnetism and Magnetic Materials (2004)

Saibal Roy Arthur Connell Matthias Ludwig N. Wang Terence O’Donnell

Microsecond

Plating (geology)

Millisecond

Pulse duration

10.1016/j.jmmm.2004.11.566

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Citations (37)

Bias field orientation driven reconfigurable magnonics and magnon−magnon coupling in triangular shaped Ni₈₀Fe₂₀ nanodot arrays

Nanotechnology (2022)

Amrit Kumar Mondal Sudip Majumder Bipul Kumar Mahato Saswati Barman Y. Otani

Reconfigurable magnonics have attracted intense interest due to their myriad advantages including energy efficiency, easy tunability and miniaturization of on-chip data communication and processing devices. Here, we demonstrate efficient reconfigurability of spin-wave (SW) dynamics as well as SW avoided crossing by varying bias magnetic field orientation in triangular shaped Ni80Fe20nanodot arrays. In particular, for a range of in-plane angles of bias field, we achieve mutual coherence between two lower frequency modes leading to a drastic modification in the ferromagnetic resonance frequency. Significant modification in magnetic stray field distribution is observed at the avoided crossing regime due to anisotropic dipolar interaction between two neighbouring dots. Furthermore, using micromagnetic simulations we demonstrate that the hybrid SW modes propagate longer through an array as opposed to the non-interacting modes present in this system, indicating the possibility of coherent energy transfer of hybrid magnon modes. This result paves the way for the development of integrated on-chip magnonic devices operating in the gigahertz frequency regime.

Magnonics

Magnon

Reconfigurability

Nanodot

Spin wave

10.1088/1361-6528/acae5e

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Transport properties of HCl doped polyaniline and polyaniline–methyl cellulose dispersion

Journal of Applied Physics (1998)

Manas Ghosh Anjan Barman Sukanta De Sudipta Chatterjee

Electrical resistance and magnetoresistance of the HCl doped polyaniline (PANI) in aqueous ethanol medium and polyaniline–methyl cellulose dispersion (PANI–MC) has been investigated at low temperature down to 1.8 K and in magnetic field up to 8 T. The weaker temperature dependence of resistivity characterized by the resistivity ratio ρr=ρ(1.8 K)/ρ(300 K) indicates that a better homogeneity and less disorder can be obtained by protonation with HCl in ethanol media. The temperature dependence of resistivity for both PANI and PANI–MC has been analyzed by three-dimensional variable range hopping (VRH) type of conduction. The samples with the resistivity ratio lying in the range of 102⩽ρr⩽103 exhibit a crossover from Mott to Efros–Shklovskii VRH conduction below 10 K. A large positive magnetoresistance at low temperature has been obtained.

Variable-range hopping

Atmospheric temperature range

10.1063/1.368141

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Citations (49)

The 2021 Magnonics Roadmap

Journal of Physics Condensed Matter (2021)

Anjan Barman G. Gubbiotti Sam Ladak A. O. Adeyeye Maciej Krawczyk

Magnonics is a budding research field in nanomagnetism and nanoscience that addresses the use of spin waves (magnons) to transmit, store, and process information. The rapid advancements of this field during last one decade in terms of upsurge in research papers, review articles, citations, proposals of devices as well as introduction of new sub-topics prompted us to present the first roadmap on magnonics. This is a collection of 22 sections written by leading experts in this field who review and discuss the current status besides presenting their vision of future perspectives. Today, the principal challenges in applied magnonics are the excitation of sub-100 nm wavelength magnons, their manipulation on the nanoscale and the creation of sub-micrometre devices using low-Gilbert damping magnetic materials and its interconnections to standard electronics. To this end, magnonics offers lower energy consumption, easier integrability and compatibility with CMOS structure, reprogrammability, shorter wavelength, smaller device features, anisotropic properties, negative group velocity, non-reciprocity and efficient tunability by various external stimuli to name a few. Hence, despite being a young research field, magnonics has come a long way since its early inception. This roadmap asserts a milestone for future emerging research directions in magnonics, and hopefully, it will inspire a series of exciting new articles on the same topic in the coming years.

Magnonics

Magnon

10.1088/1361-648x/abec1a

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Citations (437)

All-optical investigation of anisotropic spin pumping in W/CoFeB/W heterostructure

Journal of Magnetism and Magnetic Materials (2020)

Santanu Pan Samiran Choudhury Jaivardhan Sinha Anjan Barman

Spin pumping

Overlayer

Anisotropy energy

10.1016/j.jmmm.2020.166545

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Modulating conductivity of Au/CNT composites in THz frequency range: A THz resistor

2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz) (2014)

Debanjan Polley Animesh Patra Anjan Barman Rajib Kumar Mitra

We report the tunable conductivity of single walled carbon nanotubes and multi-walled carbon nanotubes with their surface walls decorated by Gold nanoparticles in the elusive THz frequency range (0.3-2.0 THz). Colloidal gold nanoparticles were synthesized by the reduction of gold chloride solution using tri-sodium citrate. A simple chemical route is followed to attach Au NP on the surfaces of carbon nanotubes. THz conductivity spectra are explained with the help of modified Universal Dielectric Response model.

Surface conductivity

10.1109/irmmw-thz.2014.6955998

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Citations (3)

Electrical and Optical Control of Spin Dynamics

Springer eBooks (2017)

Anjan Barman Jaivardhan Sinha

Dynamics

Magnetization dynamics

10.1007/978-3-319-66296-1_6

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Citations (0)

Defect-Density- and Rashba-Shift-Induced Interfacial Dzyaloshinskii–Moriya Interaction and Spin Pumping in Single-Layer Graphene/Co₂₀Fe₆₀B₂₀ Heterostructures: Implications for New-Generation Spintronics

ACS Applied Nano Materials (2022)

Amrit Kumar Mondal Sudip Majumder Sourav Sahoo Surya Narayan Panda Sumona Sinha

The quest for quantum phenomena in unconventional materials has led to the development of myriad unique systems. Because of their unusual atomic-scale interface properties and their controllability, graphene/ferromagnet heterostructures have emerged as a strong contender for next-generation spintronics. Further development demands superior properties and correlation between the different microscopic mechanisms involved. Herein, we demonstrate a superior interfacial Dzyaloshinskii–Moriya interaction (iDMI) in single-layer graphene/CoFeB/SiO2 heterostructures from asymmetric spin-wave dispersion measurement using a Brillouin light-scattering technique. The spin-wave frequencies and line widths have been correlated with structural and nanoscale morphological properties to evaluate the roles of Rashba shift and defect density for the emergence of iDMI and spin pumping for a range of thicknesses of the CoFeB layer, where the defects have been found to play a dominant role for the extrinsic spin–orbit coupling over the Rashba shift. A significantly large iDMI and spin-mixing conductance have been observed even at moderately low Ar pressure during sputter deposition of the ferromagnetic layer, which asserts further optimization of the said properties with external deposition parameters for application in next-generation energy-efficient and miniaturized spintronic and spin–orbitronic devices.

10.1021/acsanm.2c00098

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Citations (8)