Publications (25)
Phase-flip chimera induced by environmental nonlocal coupling
V. K. Chandrasekar, R. Gopal, D. V. Senthilkumar +1
We report the emergence of a collective dynamical state, namely phase-flip chimera, from an en- semble of identical nonlinear oscillators that are coupled indirectly via the dynami…
Observation and characterization of chimera states in coupled dynamical systems with nonlocal coupling
R. Gopal, V. K. Chandrasekar, A. Venkatesan +1
By developing the concepts of strength of incoherence and discontinuity measure, we show that a distinct quantitative characterization of chimera and multichimera states which occu…
Frustration Induced Chimeras and Motion in Two Dimensional Swarmalators
R. Senthamizhan, R. Gopal, V. K. Chandrasekar
Swarmalators are phase oscillators capable of simultaneous swarming and synchronization, making them potential candidates for replicating complex dynamical states. In this work, we…
Exploration of field-like torque and field-angle tunability in coupled spin-torque nano oscillators for synchronization
R. Arun, R. Gopal, V. K. Chandrasekar +1
We investigate the influence of field-like torque and the direction of the external magnetic field on a one-dimensional array of serially connected spin-torque nano oscillators, ha…
Mechanism for intensity induced chimera states in globally coupled oscillators
V. K. Chandrasekar, R. Gopal, A. Venkatesan +1
We identify the mechanism behind the existence of intensity induced chimera states in globally coupled oscillators. We find that the effect of intensity in the system is to cause m…
Phase locking of spin transfer nano-oscillators using common microwave sources
R. Gopal, B. Subash, V. K. Chandrasekar +1
In this paper, we study typical nonlinear phenomenon of phase-locking or synchronization in spin-torque nano oscillators (STNOs). To start with the oscillators are considered as un…
Observation of sequential three-body dissociation of camphor molecule -- a native frame approach
S. De, S. Mandal, Sanket Sen +11
The three-body dissociation dynamics of the dicationic camphor molecule (CHO) resulting from Auger decay are investigated using soft X-ray synchrotron radiatio…
Analysis of COVID-19 in India using vaccine epidemic model incorporating vaccine effectiveness and herd immunity
V. R. Saiprasad, R. Gopal, V. K. Chandrasekar +1
COVID-19 will be a continuous threat to human population despite having a few vaccines at hand until we reach the endemic state through natural herd immunity and total immunization…
Applicability of 0-1 Test for Strange Nonchaotic Attractors
R. Gopal, A. Venkatesan, M. Lakshmanan
We show that the recently introduced 0-1 test can successfully distinguish between strange nonchaotic attractors(SNAs) and periodic/quasiperiodic/chaotic attractors, by suitably ch…
Swarmalators with frequency-weighted interactions
R. Senthamizhan, R. Gopal, V. K. Chandrasekar
We investigate the role of frequency-weighted interactions in a solvable model of one-dimensional (1D) swarmalators confined to a ring, where both spatial and phase couplings are s…
Dynamical modelling and analysis of COVID-19 in India
R. Gopal, V. K. Chandrasekar, M. Lakshmanan
We consider the pandemic spreading of COVID-19 in India after the outbreak of the coronavirus in Wuhan city, China. We estimate the transmission rate of the initial infecting indiv…
Penning Spectroscopy and Structure of Acetylene Oligomers in He Nanodroplets
S. Mandal, R. Gopal, M. Shcherbinin +8
Embedded atoms or molecules in a photoexcited He nanodroplet are well-known to be ionized through inter-atomic relaxation in a Penning process. In this work, we investigate the Pen…
Self-oscillations induced by self-induced torque in magnetic double tunnel junction
R. Arun, R. Gopal, V. K. Chandrasekar +1
Self-oscillations of the magnetization due to self-induced torque (SIT) in a magnetic double tunnel junction that consists of perpendicularly polarized, pinned and free layers is i…
Analysis of the second wave of COVID-19 in India based on SEIR model
R. Gopal, V. K. Chandrasekar, M. Lakshmanan
India was under a grave threat from the second wave of the COVID-19 pandemic particularly in the beginning of May 2021. The situation appeared rather gloomy as the number of infect…
Large Amplitude Spin-Hall Oscillations due to Field-like Torque
R. Arun, R. Gopal, V. K. Chandrasekar +1
Large amplitude spin-Hall oscillations are identified in a ferromagnetic layer with two perpendicular in-plane easy axis in the presence of field-like torque without any polarizer…
Chimera at the phase-flip transition of an ensemble of identical nonlinear oscillators
R. Gopal, V. K. Chandrasekar, D. V. Senthilkumar +2
A complex collective emerging behavior characterized by coexisting coherent and incoherent do- mains is termed as a chimera state. We bring out the existence of a new type of chime…
Effect of biharmonic coupling in frequency-weighted Kuramoto oscillators
R. Senthamizhan, R. Gopal, V. K. Chandrasekar
The paper studies how combining frequency‑weighted and biharmonic coupling in globally coupled Kuramoto phase oscillators alters their collective dynamics, revealing multiple stabl…
Effect of asymmetry parameter on the dynamical states of nonlocally coupled nonlinear oscillators
R. Gopal, V. K. Chandrasekar, D. V. Senthilkumar +2
We show that coexisting domains of coherent and incoherent oscillations can be induced in an ensemble of any identical nonlinear dynamical systems using the nonlocal rotational mat…
Influence of Asymmetric Parameters in Higher-Order Coupling With Bimodal Frequency Distribution
M. Manoranjani, R. Gopal, D. V. Senthilkumar +2
We investigate the phase diagram of the Sakaguchi-Kuramoto model with a higher order interaction along with the traditional pairwise interaction. We also introduce asymmetry parame…
Effect of interlayer exchange coupling in spin-torque nano oscillator
R. Arun, R. Gopal, V. K. Chandrasekar +1
The dynamics of the magnetization of the free layer in a spin-torque nano oscillator (STNO) influenced by a noncollinear alignment between the magnetizations of the free and pinned…
Dynamics of coupled modified Rossler oscillators: the role of nonisochronicity parameter
C. Ramya, R. Gopal, R. Suresh +1
The amplitude-dependent frequency of the oscillations, termed \emph{nonisochronicity}, is one of the essential characteristics of nonlinear oscillators. In this paper, the dynamics…
Complex dynamics generated by negative and positive feedback delays of a prey-predator system with prey refuge: Hopf bifurcation to Chaos
Debaldev Jana, R. Gopal, M. Lakshmanan
Various field and laboratory experiments show that prey refuge plays a significant role in the stability of prey-predator dynamics. On the other hand, theoretical studies show that…
High frequency oscillations in spin-torque nano oscillator due to bilinear coupling
R. Arun, R. Gopal, V. K. Chandrasekar +1
Exchange coupling in an interfacial context is crucial for spin-torque nano oscillator (STNO) that consists of a non-magnetic spacer which is alloyed with a ferromagnetic material.…
Spin Torque Oscillations Triggered by In-plane Field
R. Arun, R. Gopal, V. K. Chandrasekar +1
We study the dynamics of a spin torque nano oscillator that consists of parallelly magnetized free and pinned layers by numerically solving the associated Landau-Lifshitz-Gilbert-S…
Influence of field-like torque in synchronization of spin torque oscillators
R. Arun, R. Gopal, V. K. Chandrasekar +1
The magnetization dynamics of two parallelly coupled spin torque oscillators, destabilization of steady states and removal of multistability, are investigated by taking into accoun…