Highlight Articles

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  Enhanced figure of merit of polycrystalline PtSe₂/PtSe₂ structures at room temperature by a facile wet-transfer stacking method

  Jung‑Min Cho, Yun‑Ho Kim, Won‑Yong Lee et al.

  J. Korean Phys. Soc. 85(8), 643 - 649 (2024)

  We present a promising approach to significantly improve the in-plane thermoelectric (TE) figure-of-merit (ZT) of few-layer PtSe2 films at room temperature by stacking PtSe2 layers with uniform thickness. As the number of stacked layers increases, the Seebeck coefficient enhances significantly with relatively constant electrical conductivity. Meanwhile, the thermal conductivity shows a significant decrease, resulting in an increase in the ZT factor by ~380% compared to the single-layer PtSe2 film. This remarkable increase in ZT factor shows the potential for a considerable improvement in TE properties of semimetallic PtSe2 with a new technique called facile wet-transfer stacking.
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  Initial image-based approach may enhance direct reciprocity for cooperation evolution

  Sunhee Chae, Hyeong‑Chai Jeong

  J. Korean Phys. Soc. 85(6), 525 - 533 (2024)

  We explore the evolution of strategies in the iterated Prisoner’s Dilemma within finite populations, where players repeatedly interact with the same partners and have access to public records of others' actions. We analyze a variety of discriminating strategies that utilize both direct reciprocity (based on repeated interactions) and indirect reciprocity (based on public information), along with strategies of always cooperating or always defecting. Our results show that a strategy combining tit-for-tat for repeated encounters and indirect information for initial interactions is generally the most effective, except when the benefits greatly outweigh the costs, where the standard tit-for-tat strategy prevails.
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  Quantum computation by cooling

  Jaeyoon Cho

  J. Korean Phys. Soc. 85(5), 397 - 405 (2024)

  Adiabatic quantum computation solves problems by finding the ground states of many-body Hamiltonians, but its analysis is challenging. This study proposes an alternative cooling-based method, inspired by cavity cooling, where the system's entropy is extracted by discarding ancilla qubits, driving the system toward its ground state. This cooling approach is computationally equivalent to quantum circuits. We demonstrate its application to combinatorial optimization problems by numerical simulation, incorporating a mechanism that allows the system to escape local energy minima via high-order transitions.
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  Effect of proton-beam irradiation on cell survival of MCF-7 and its chemo-resistant subgroups

  Sushma Maharjan, Min-Gu Lee, Kyung-Soo Nam et al.

  J. Korean Phys. Soc. 85(3), 271 - 278 (2024)

  This investigation revealed that proton-beam resistance in drug-resistant breast cancer cells is closely correlated with the regulation of RAD51, Ku80 ad survivin. Therefore, this study suggests that a specialized strategy is required to enhance the efficacy of proton-beam therapy through targeting RAD51, Ku80 and survivin, particularly in patients exhibiting chemoresistance.
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  Hole induced half-metallic 2H VSe₂ thin film with high Curie temperature and optical transparency

  Ganie Suhail Ahmad, Jisang Hong

  J. Korean Phys. Soc. 84(6), 462 - 469 (2024)

  Our Study systematically explores thickness-dependent magnetic and optical properties in 2H VSe₂ films. We observe a transition from antiferromagnetic(AFM) to ferromagnetic(FM) states with increasing film thickness and critical hole carrier doping concentrations. Notably, a half-metallic behavior is observed, with consistent local magnetic moments for V atoms and negatively induced moments for Se atoms. Despite a slight reduction with increasing film thickness, the curie temperature remains significantly above 300K, ensuring FM state stability. Additionally, refractive index and reflectivity increase with layer thickness, indicating potential applications in optical devices. Overall, our findings suggest promising applications of hole-doped 2H VSe₂ in spintronics and optical devices based on magnetic materials.
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  Random‑singlet‑like state emergent in s = 5/2 frustrated cubic lattice

  Chanhyeon Lee, Sang‑Kwon Lee, Suheon Lee et al.

  J. Korean Phys. Soc. 84(2), 151 - 157 (2024)

  The existence and nature of a random singlet phase in higher dimensions remains elusive, despite certain theories and experiments alluding to its potential stability. In the frustrated cubic antiferromagnet La3Sb3Mn2O14, we identify a scaling relation in ac magnetic susceptibility and magnetization with a scaling exponent of 0.53, giving evidence for emergent random singlets rather than a spin glass. This finding extends the notion of a random-singlet state from low-dimensional quantum to three-dimensional S=5/2 frustrated spin systems.
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  Quantum scales of galaxies from ultralight dark matter

  Jae‑Weon Lee

  J. Korean Phys. Soc. 83(12), 1013 - 1018 (2023)

  We propose that the ultralight dark matter (ULDM) model has characteristic scales for physical quantities of observed galaxies such as mass, size, acceleration, mass flux, and angular momentum from quantum mechanics. The typical angular momentum per dark matter particle is ℏ and the typical physical quantities are functions of specific angular momentum ℏ/m and average background density of the particles. If we use the Compton wavelength instead for the length scale, we can obtain bounds for these physical quantities. We suggest that the physical scales of galaxies depend on the time of their formation and that these characteristic scales are related to some mysteries of observed galaxies.