International Journal of Physics | Vol. 4, No. 5, May 2013 | pp. 33–40
DOI: 10.46882/2013/IJP/000037
Research Article
Title: High-Pressure Mechanical Stability and Elastic Anisotropy of Advanced Transition Metal Diborides
Names of Authors: Y. V. Petrov¹, E. M. Gallagher²
Authors’ Affiliations: ¹Department of Theoretical Physics, Saint Petersburg State University, Saint Petersburg 199034, Russia; ²School of Physics, Trinity College Dublin, Dublin 2, Ireland
Abstract: Transition metal diborides are highly valued for their exceptional hardness, high melting points, and electrical conductivity under extreme operating conditions. This investigation evaluates the high-pressure mechanical stability and elastic anisotropy of titanium diboride (TiB2) and zirconium diboride (ZrB2). We performed first-principles density functional theory calculations using the generalized gradient approximation up to hydrostatic pressures of 100.0 GPa. At zero pressure, the calculated bulk modulus of TiB2 is B0 = 242.0 GPa, which closely matches experimental diamond anvil cell measurements within a 1.2% margin. As the pressure scales upward, the single-crystal elastic constants (C11, C33, C44, C12, and C13) increase linearly. Both materials strictly satisfy the generalized Born stability criteria across the entire pressure range, demonstrating robust mechanical integrity. We quantified the degree of elastic anisotropy using the universal anisotropy index (AU). The calculations show that ZrB2 exhibits a higher level of shear anisotropy compared to TiB2, with its index increasing from 0.15 to 0.38 at 100.0 GPa. This behavior indicates that ZrB2 is more susceptible to microcrack propagation along the basal plane under high shear strain. These precise elastic parameters offer valuable data for designing ultra-high-temperature ceramics for aerospace applications.
Keywords: Transition metal diborides; density functional theory; elastic constants; high pressure; mechanical stability; elastic anisotropy
Manuscript Timeline: Received: February 11, 2013; Revised: March 24, 2013; Accepted: April 10, 2013; Published: May 16, 2013
Citation: Petrov, Y. V., & Gallagher, E. M. (2013). High-Pressure Mechanical Stability and Elastic Anisotropy of Advanced Transition Metal Diborides. International Journal of Physics, 4(5), 33–40.
International Journal of Physics | Vol. 4, No. 4, April 2013 | pp. 25–32
DOI: 10.46882/2013/IJP/000036
Research Article
Title: Topological Edge States and Robust Transport in Two-Dimensional Magneto-Optical Photonic Crystals
Names of Authors: J. W. Park¹, S. T. Harrison²
Authors’ Affiliations: ¹Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea; ²Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
Abstract: Topological insulators have inspired new avenues for manipulating electromagnetic wave propagation without backscattering losses. This study designs and simulates a two-dimensional magneto-optical photonic crystal exhibiting robust, unidirectional topological edge states. The crystal lattice consists of a triangular array of ferrite rods embedded in an air matrix. It is subjected to an external static magnetic field applied parallel to the rod axes. We calculated the photonic band structure using the finite element method across the microwave spectrum. The application of a 0.3 T magnetic field breaks time-reversal symmetry. This breaking lifts the degeneracy at the Dirac points, opening a topological band gap with a normalized width of Δω/ω0 = 6.5%. We calculated a non-zero Chern number of C = +1 for the lowest bands, confirming the non-trivial topology of the bulk system. To demonstrate transport robustness, we simulated the propagation of an electromagnetic wave packet past sharp corners and large structural defects. The edge mode bypassed these obstacles with a high transmission efficiency of 99.2% ± 0.3%, showing zero backscattering. These findings provide solid engineering guidelines for developing backscattering-immune optical isolators, delay lines, and compact photonic integrated circuits.
Keywords: Topological photonics; edge states; magneto-optical effect; finite element method; Chern number; backscattering immunity
Manuscript Timeline: Received: January 08, 2013; Revised: February 18, 2013; Accepted: March 05, 2013; Published: April 11, 2013
Citation: Park, J. W., & Harrison, S. T. (2013). Topological Edge States and Robust Transport in Two-Dimensional Magneto-Optical Photonic Crystals. International Journal of Physics, 4(4), 25–32.
International Journal of Physics | Vol. 4, No. 2, February 2013 | pp. 9–16
DOI: 10.46882/2013/IJP/000034
Research Article
Title: Structural Evolution and Transport Anomalies in Iron-Based Pnictide Superconductors under Hydrostatic Pressure
Names of Authors: A. A. Menshikov¹, B. J. Holford²
Authors’ Affiliations: ¹Institute for Solid State Physics, Russian Academy of Sciences, Chernogolovka 142432, Russia; ²Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
Abstract: The interplay between structural transitions and high-temperature superconductivity in iron-based pnictides is a focal topic in modern condensed matter physics. This work details the structural evolution and electronic transport anomalies in Ba(Fe1-xCox)²As² single crystals under hydrostatic pressures up to 12.0 GPa. The experiments used a non-magnetic diamond anvil cell setup. At ambient pressure conditions, the parent material shows an structural transition from tetragonal to orthorhombic symmetry at Ts = 134 K. This change occurs alongside an antiferromagnetic spin-density-wave phase transition at TSDW = 132 K. Applying hydrostatic pressure systematically suppresses both transitions. The spin-density-wave state disappears completely at a critical pressure value of P = 4.2 GPa. Simultaneously, a superconducting dome emerges, reaching a maximum critical transition temperature of Tc = 24.8 K. Hall effect coefficients show a sudden sign reversal near the optimal pressure setting. This indicates a significant reconfiguration of the Fermi surface geometry and changes in carrier concentration levels. Our findings confirm that high-pressure conditions reconstruct the multi-band nesting parameters. This reconstruction enhances the spin-fluctuation pairing mechanisms responsible for high-temperature superconductivity.
Keywords: Superconductivity; pnictides; hydrostatic pressure; diamond anvil cell; spin-density wave; Fermi surface
Manuscript Timeline: Received: November 5, 2012; Revised: December 18, 2012; Accepted: January 8, 2013; Published: February 12, 2013
Citation: Menshikov, A. A., & Holford, B. J. (2013). Structural Evolution and Transport Anomalies in Iron-Based Pnictide Superconductors under Hydrostatic Pressure. International Journal of Physics, 4(2), 9–16.
International Journal of Physics | Vol. 4, No. 3, March 2013 | pp. 17–24
DOI: 10.46882/2013/IJP/000035
Research Article
Title: Characterization of Plasma Chemistry and Ion Energy Distributions in Low-Pressure Carbon Tetrafluoride Discharges
Names of Authors: L. K. Rousseau¹, M. A. Al-Hussaini²
Authors’ Affiliations: ¹Laboratoire de Physique des Plasmas, École Polytechnique, 91128 Palaiseau, France; ²Department of Physics, Faculty of Science, Kuwait University, Safat 13060, Kuwait
Abstract: Carbon tetrafluoride (CF4) plasmas are extensively utilized for precise oxide etching within industrial semiconductor fabrication processes. This paper evaluates the internal plasma chemistry and measures the corresponding ion energy distributions (IEDs) within a low-pressure inductively coupled plasma reactor. The system was operated at an excitation frequency of 13.56 MHz under gas pressures varying from 0.5 Pa to 5.0 Pa. We integrated a mass spectrometer with an energy analyzer directly into the grounded substrate electrode to capture real-time flux parameters. The experimental findings indicate that the CF3+ ion dominates the total positive ion flux across all tested configurations. It accounts for more than 70.0% of the total ion concentration. As the radio-frequency power increased from 100.0 W to 500.0 W, the average ion energy shifted from 34.2 eV to 58.5 eV. This shift occurred alongside a narrowing of the IED full-width at half-maximum from 12.4 eV down to 4.1 eV. Numerical simulations using a zero-dimensional global model match the observed neutral radical densities within a minor ±8.0% margin. These simulations show that electron-impact dissociation of CF4 is the primary pathway generating reactive fluorine atoms. This work provides critical kinetic tracking data necessary for refining thin-film etching profiles on sub-22 nm node architectures.
Keywords: Plasma chemistry; carbon tetrafluoride; ion energy distribution; mass spectrometry; semiconductor etching; inductively coupled plasma
Manuscript Timeline: Received: December 14, 2012; Revised: January 22, 2013; Accepted: February 09, 2013; Published: March 15, 2013
Citation: Rousseau, L. K., & Al-Hussaini, M. A. (2013). Characterization of Plasma Chemistry and Ion Energy Distributions in Low-Pressure Carbon Tetrafluoride Discharges. International Journal of Physics, 4(3), 17–24.
International Journal of Physics | Vol. 4, No. 1, January 2013 | pp. 1–8
DOI: 10.46882/2013/IJP/000033
Research Article
Title: Non-Equilibrium Phase Transitions in Driven Dissipative Rydberg Atom Arrays
Names of Authors: F. K. Zimmermann¹, Y. S. Kim²
Authors’ Affiliations: ¹Institut für Theoretische Physik, Universität Stuttgart, 70569 Stuttgart, Germany; ²Department of Physics and Astronomy, Seoul National University, Seoul 08826, South Korea
Abstract: Strongly interacting Rydberg atom systems offer an ideal platform for simulating quantum phases and exploring non-equilibrium statistical mechanics. This paper investigates non-equilibrium phase transitions occurring within a two-dimensional square lattice array of Rydberg atoms. The system is subjected to coherent laser driving fields alongside uniform spontaneous dephasing processes. The strong van der Waals interactions between high-lying Rydberg states induce a Rydberg blockade mechanism. We model the steady-state phase diagram using a cluster mean-field approximation paired with extensive tensor network simulations. The data reveal a clear phase boundary separating a spatially uniform steady state from an ordered antiferromagnetic crystal phase. This structural transition displays significant bistable hysteresis loops when tuning the laser amplitude parameters. The critical exponent beta, which governs the order parameter behavior near the transition point, is calculated as beta = 0.32 ± 0.02. This value deviates from standard equilibrium Ising universality class metrics. Furthermore, we show that introducing spatial noise to the laser field suppresses the bistable state region. It shifts the phase transition boundary toward higher driving frequencies. This work clarifies the roles of dissipation and quantum correlations in driven many-body systems.
Keywords: Rydberg atoms; non-equilibrium phase transition; Rydberg blockade; tensor network; bistability; hysteresis loop
Manuscript Timeline: Received: October 12, 2012; Revised: November 22, 2012; Accepted: December 10, 2012; Published: January 14, 2013
Citation: Zimmermann, F. K., & Kim, Y. S. (2013). Non-Equilibrium Phase Transitions in Driven Dissipative Rydberg Atom Arrays. International Journal of Physics, 4(1), 1–8.
International Journal of Physics | Vol. 3, No. 12, December 2012 | pp. 91–98
DOI: 10.46882/2012/IJP/000032
Research Article
Title: Heavy-Flavour Hadron Production Cross-Sections in Proton-Proton Collisions at Center-of-Mass Energy of 8 TeV
Names of Authors: S. P. McCarthy¹, A. M. Geller²
Authors’ Affiliations: ¹European Organization for Nuclear Research (CERN), CH-1211 Geneva 23, Switzerland; ²Department of Physics, University of Science and Technology of China, Hefei 230026, China
Abstract: Measuring heavy-flavour hadron production cross-sections provides a stringent quantitative test of perturbative quantum chromodynamics (pQCD) scaling limits. This study presents the absolute differential production cross-sections for D0, D+, and D*+ mesons. The measurements use data gathered from proton-proton collisions at a center-of-mass energy of 8 TeV. The data were recorded by a high-resolution forward spectrometer tracking system. The kinematic range investigated covers a transverse momentum span of 2.0 GeV/c < pT < 12.0 GeV/c within a rapid interval of 2.0 < y < 4.5. The reconstruction of charm mesons relied on distinct hadronic decay channels, specifically D0 decaying into K- and π+. The experimental cross-section results are evaluated against theoretical next-to-leading-order calculations (FONLL). The empirical cross-sections exceed the baseline FONLL predictions by a systematic factor of 1.35 ± 0.12. However, they stay consistent within the broader theoretical uncertainty bands of the model. The ratio of production yields between D+ and D0 mesons remains uniform across different transverse momentum values, yielding an average ratio of 0.44 ± 0.03. These precise measurements improve the calibration of parton distribution functions. They also establish baseline targets for evaluating cold nuclear matter effects in heavy-ion collision experiments.
Keywords: Hadron production; charm mesons; quantum chromodynamics; cross-sections; proton-proton collisions; forward spectrometer
Manuscript Timeline: Received: September 15, 2012; Revised: October 30, 2012; Accepted: November 15, 2012; Published: December 17, 2012
Citation: McCarthy, S. P., & Geller, A. M. (2012). Heavy-Flavour Hadron Production Cross-Sections in Proton-Proton Collisions at Center-of-Mass Energy of 8 TeV. International Journal of Physics, 3(12), 91–98.