Highlight Articles

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  Simulation of classical axion electrodynamics using COMSOL multiphysics

  Junu Jeong, Younggeun Kim, Sungjae Bae et al.

  J. Korean Phys. Soc. 83(3), 161 - 167 (2023)

  While the fundamental equations governing the axion-photon interaction are widely recognized, their comprehensive calculations become imperative when applied to intricate experimental setups. In this work, we utilize COMSOL Multiphysics, a commercially available software that employs the finite element method, to numerically solve the partial differential equations underlying axion electrodynamics. We simulate diverse experimental schemes, including axion haloscope and axion-photon regeneration. We show that the numerical simulations are in excellent agreement with the analytical calculations, confirming that they are reliable for describing axion electrodynamics.
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  Identification of octahedral configuration in strained SrRuO₃ thin films

  Tae Hwa Eom, Sang A. Lee, Jae‑Yeol Hwang

  J. Korean Phys. Soc. 83(1), 65 - 71 (2023)

  Strong modulation between crystal symmetry and the corresponding RuO₆ octahedral configurations were verified by structural model calculations based on the diffraction data of 20 individual half-order peaks. This proves that the compressively strained SrRuO₃ thin film has pseudo-orthorhombic (monoclinic, P21/m, #11) structure with the BO6 configuration of a⁺a^–c^– at 25 °C and tetragonal (I4/mcm, #140) with the octahedral tilt of a⁰a⁰c^– above 285 °C. The structural phase transition from pseudo-orthorhombic to the tetragonal structure was determined at around 285 °C and epitaxial strain was persistent during the structural phase transition in the fully strained SrRuO₃/SrTiO₃ heterostructured thin film.
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  40-W 352-nm single-frequency nanosecond pulsed rod-type fiber laser

  Yong‑Ho Cha, Byungjae Chun, Hyunmin Park

  J. Korean Phys. Soc. 82(12), 1157 - 1162 (2023)

  High-power single-frequency ultraviolet laser pulses are generated by third-harmonic generation of 1056-nm laser pulses from a Yb-doped fiber laser system. The fiber laser system utilizes a rod-type fiber in its final amplifier for the generation of 108-W 1056-nm laser pulses, and two LBO crystals are used for the efficient second- and third-harmonic generation, respectively. The average output power of 352-nm laser is more than 40 W at a repetition rate of 900 kHz, and the pulse duration is 12 ns with a measured linewidth of less than 150 MHz, which is ideal for the isotope-selective photo-dissociation of formaldehyde molecules.
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  Explicit dispersion relations for warm fluid waves in a uniform plasma (invited)

  Min Uk Lee, Gunsu S. Yun, Jeong‑Young Ji

  J. Korean Phys. Soc. 82(8), 740 - 747 (2023)

  Computing a dispersion relation for warm plasma waves generally requires numerical methods since the relation is expressed as an implicit function of frequency and wavenumber. In this work, we present an explicit dispersion relation that provides an accurate analytical solution for the dispersion without relying on numerical methods. The derived formula can even describe the dispersion relation near the cyclotron resonance that the implicit relation cannot represent. We verify the validity and accuracy of the formula by comparing its analytical solutions with the numerical results obtained from the implicit dispersion relations and fully kinetic particle-in-cell (PIC) simulations.
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  Room-temperature ferromagnetism observed in graphene oxide

  DaYea Oh, Bae Ho Park, Duk Hyun Lee et al.

  J. Korean Phys. Soc. 82(8), 786 - 792 (2023)

  We investigate magnetic properties of locally oxidized graphene using atomic force microscope lithography, which reduces the possibility of magnetic contamination. Raman spectroscopy analysis reveals that the graphene oxide has a different atomic structure than pristine graphene. Magnetic force microscopy data demonstrate that the graphene oxide has a net magnetization pointing out of the surface plane. Magneto-optical Kerr effect data exhibit small but clear hysteresis loops with non-zero remanent magnetization. X-ray magnetic circular dichroism photoemission electron microscope measurements identifies remarkable asymmetry in carbon K edge spectra, strongly suggesting that the observed ferromagnetic order in the graphene oxide layer is intrinsic.
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  Quantum critical region of a two‑dimensional spin‑half XXZ model

  Ji‑Woo Lee, Harold U. Baranger

  J. Korean Phys. Soc. 82(7), 688 - 691 (2023)

  We study the properties of a quantum critical region of an XXZ model in 2D. The quantum critical point at zero temperature evolves as the temperature increases. Using the quantum Monte Carlo method with stochastic series expansions, we obtained the phase diagram. For the finite-temperature transitions from a paramagnet to an XY critical phase, we measured the superfluid stiffness and used the finite-size scaling to obtain the critical temperatures. For the paramagnet-to-antiferromagnetic transitions, we measured the compressibility to obtain the critical points.
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  Nuclear physics research at CENS

  S. Ahn, D. S. Ahn, S. Kim et al.

  J. Korean Phys. Soc. 82(6), 537 - 546 (2023)

  The Center for Exotic Nuclear Studies (CENS) at the Institute for Basic Science was founded in December, 2019, to address many fundamental problems in nuclear physics and astrophysics. CENS is a rare isotope nuclear research center and consists of four research groups (nuclear structure, nuclear reaction, nuclear astrophysics and nuclear theory). The center has shown remarkable research outputs and capabilities in experimental and theoretical exotic nuclear studies during last two years. Experimental devices are under development extensively at CENS and they will be used for performing key nuclear studies at rare isotope facilities including RIKEN(Japan), FRIB(US), and RAON in Korea.