Faculty Publications
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Publications by NITK Faculty
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Item Criticality of charged ads black hole with a global monopole(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2020) Naveena Kumar, A.; Ahmed Rizwan, C.L.A.; Ajith, K.M.We discuss the phase transition of charged AdS black hole surrounded by a global monopole. The cosmological constant is taken as fluid pressure and the corresponding conjugate variable as volume. In this extended phase space, the criticality is investigated from P-V isotherms, Gibbs free energy behavior and coexistence curves. The critical behavior of the Black Hole is analogous to classical van der Waals gas. This is further verified by looking at the critical exponents. The magnetic monopole parameter affects the phase structure of the black hole significantly. © Springer Nature Singapore Pte Ltd 2020.Item The Role of Global Monopole in Joule–Thomson Effect of AdS Black Hole(Springer Science and Business Media Deutschland GmbH, 2021) Naveena Kumara, A.; Ahmed Rizwan, C.L.; Ajith, K.M.We study the throttling process of the AdS black hole with a global monopole in the extended phase space. In the approach followed, the cosmological constant and the black hole mass are identified with the thermodynamic pressure and enthalpy, respectively. We investigate the dependency of the inversion temperature and isenthalpic curves on the global monopole parameter η. Our study shows a close resemblance between the phase transition of the black hole in the extended phase space and Van der Waals fluid. The presence of global monopole plays an important role in the throttling process. © 2021, Springer Nature Singapore Pte Ltd.Item Effect of dark energy in geometrothermodynamics and phase transitions of regular Bardeen AdS black hole(Springer, 2019) Ahmed Rizwan, C.L.; Naveena Kumara, A.; Rajani, K.V.; Vaid, D.; Ajith, K.M.We study the thermodynamics and geometrothermodynamics of regular Bardeen-AdS black hole with quintessence. The thermodynamics of the black hole is scrutinised using Temperature–Entropy (T–S), Pressure–Volume (P–v) and Gibbs energy plots, which indicates a critical behaviour. The behaviour is also confirmed from the divergence of specific heat against entropy, which shows a second-order phase transition. Furthermore, we observe that the quintessence state parameter ? shifts the transition point to lower entropy values. Using the concept of thermodynamic Ruppeiner and Weinhold geometry, we calculated the thermodynamic curvature scalar RR and RW in the quintessence dark energy regime (?= - 2 / 3 ). While these curvature scalars enable us to identify the critical behaviour, they do not show divergence at the phase transition points observed in specific heat study. To resolve this puzzle, we have adopted the method of geometrothermodynamics proposed by Hernando Quevedo. Choosing a Legendre invariant ‘Quevedo’ metric, the curvature scalar RQ shows singularity at the same point as seen in the specific heat divergence. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.Item Euclidean thermodynamics and Lyapunov exponents of Einstein–Power–Yang–Mills AdS black holes(Springer Nature, 2025) Karthik, R.; Dillirajan, D.; Ajith, K.M.; Hegde, K.; Punacha, S.; Naveena Kumara, A.N.We study the thermodynamics of Einstein–Power–Yang–Mills AdS black holes via the Euclidean path integral method, incorporating appropriate boundary and counterterms. By analyzing unstable timelike and null circular geodesics, we demonstrate that their Lyapunov exponents reflect the thermodynamic phase structure obtained from the Euclidean action. Specifically, the small-large black hole phase transition, analogous to a van der Waals fluid, is signaled by a discontinuity in the Lyapunov exponent. Treating this discontinuity as an order parameter, we observe a universal critical exponent of 1/2, consistent with mean-field theory. These results extend previous insights from black hole spacetimes with Abelian charges to scenarios involving nonlinear, non-Abelian gauge fields, highlighting the interplay between black hole thermodynamics and chaotic dynamics. © The Author(s) 2025.