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All Journal Indonesian Physical Review
Widiyani, Agustina
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Education Physics

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HAWKING TEMPERATURE IN SCHWARZSCHILD BLACK HOLES WITH QUINTESSENCE DARK ENERGY Widiyani, Agustina; Sari, Ana Novita; Permanasari, Ikah Ning Prasetiowati; Satria, Eko; Pohan, Azrul Sulaiman Karim; Kesuma, Weni Ayu Puja; Pardede, Indra; Suroso, Agus
Indonesian Physical Review Vol. 8 No. 2 (2025)
Publisher : Universitas Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/ipr.v8i2.454

Abstract

Black holes are thermodynamic objects that emit Hawking radiation near the event horizon of a black hole according to the theory of quantum gravity in curved space-time. This radiation is manifested as the temperature of a black hole, known as the Hawking temperature. According to black hole thermodynamics, the black hole horizon area corresponds to the entropy. The increase in the horizon area is predicted due to the influence of dark energy, which can push the horizon of the black hole away from its center, thus significantly affecting the radiation of the black hole. Here, we investigate the Hawking temperature of the Schwarzschild black hole under the effect of quintessence dark energy. The results show that the increase in quintessence reduces the horizon radius of the black hole and lowers its Hawking temperature, highlighting the direct relationship between dark energy and black hole dynamics.
FIRST-PRINCIPLES STUDY OF MAGNETIC ANISOTROPY ENERGY IN TWO-DIMENSIONAL FERROMAGNETIC CrI3 Mecci, Puke Lajaladita Litle; Monica, Annisa; Sinurat, Iin Riananda Br; Widiyani, Agustina; Rajak, Abdul; Pardede, Indra
Indonesian Physical Review Vol. 6 No. 1 (2023)
Publisher : Universitas Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/ipr.v6i1.191

Abstract

First-principles calculations are increasingly crucial in searching for new materials with customized properties or new functionality. First-principles calculations are superior in speed and cost, and comparable to experiments in terms of accuracy. Two-dimensional (2D) ferromagnetism materials were successfully fabricated experimentally in atomic thin films of CrI3. 2D intrinsic ferromagnetism with perpendicular magnetic anisotropy energy (PMAE) is an encouraging applicant compatible with high-density magnetic storage applications. In this study, spin density functional calculations are investigated on the magnetic anisotropy energy (MAE) in 2D monolayer ferromagnetic CrI3 using a first-principles electronic structure calculation. We include the MAE part calculation from the magnetocrystalline anisotropy energy (MCAE) that comes from the spin-orbit coupling (SOC). In the present calculation, the MCAE part, in addition to a usual scheme of total energy (TE), was evaluated using a grand-canonical force theorem (GCFT) scheme. The MCAE of 2D monolayer ferromagnetic CrI3 is 1.7 meV/unit cell and verified it has an easy-axis perpendicular to the crystal plane, which is a good agreement with experimental measurement. In the latter scheme, employing GCFT, we evaluated atom-resolved, k-resolved, and atomic k-resolved analyses for MCAE can be performed. From the GCFT result, the Cr atom indicates that it is the primary origin of PMAE in the atom-resolved MCAE. The negative MCAE contribution is in points, and the positive MCAE is mainly placed at the line in the 2D first Brillouin zone. Our systematic calculation in this work may also help design an effective structure of monolayer CrI3 in new 2D material magnetic sensor and spintronic device designs.
Kajian First Principles tentang Sifat Elektronik dan Optik Semikonduktor ZnO dengan co-doping CoX (X = Cr, Mn, Ti, V) Prayoga, Harry; Rajak, Abdul; Widiyani, Agustina; Prayogo, Priyan; Musfiroh, Fatimatul; Pardede, Indra
Indonesian Physical Review Vol. 9 No. 1 (2026)
Publisher : Universitas Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/ipr.v9i1.530

Abstract

The development of solar energy materials is essential for achieving the Sustainable Development Goals (SDGs). However, their performance is often limited by the electronic and optical properties of commonly used semiconductors. Unlike previous DFT studies mostly focused on non–transition metal dopants (e.g., Al, Ga), this work explores pristine ZnO, single cobalt (Co) doping, and CoX (X = chromium (Cr), manganese (Mn), titanium (Ti), and vanadium (V)) codoping to reveal how single and dual 3d-orbital interactions modify its electronic and optical behavior. This study investigates the effects of transition metal codoping CoX (X = Cr, Mn, Ti, V) on ZnO using Density Functional Theory (DFT) and DFT with Hubbard U correction (DFT+U) within the Generalized Gradient Approximation (GGA) to evaluate opto-electronic properties. The bandgap of pristine ZnO was calculated as ~0.80 eV with standard DFT, while ZnO-Co and ZnO-CoX exhibited zero bandgap with a flatband due to conduction band overlap with the Fermi level, indicating metallic behavior resulting from d-orbital contributions. DFT+U improved the pristine ZnO bandgap to ~1.08 eV, although Co-doped and CoX co-doped remained metallic. Orbital resolved analysis shows that Ti and V introduce states near the valence band, while Cr and Mn shift states deeper below the Fermi level, reflecting distinct d-orbital interactions. The theoretical band gaps underestimated experimental values due to strong electron correlation in ZnO. Optical analysis revealed that Co and CoX codoping shifts the absorption edge into the visible range and enhances the absorption intensity. The presence of dopants alters the electronic band structure and enhances optical absorption in the visible range, underscoring their effectiveness in engineering ZnO-based semiconductors for optimized optoelectronic responses.
Co-Authors Agus Suroso Eko Satria Ikah N. P. Permanasari Indra Pardede Kesuma, Weni Ayu Puja Mecci, Puke Lajaladita Litle Monica, Annisa Musfiroh, Fatimatul Pohan, Azrul Sulaiman Karim Prayoga, Harry Prayogo, Priyan Rajak, Abdul SARI, ANA NOVITA Sinurat, Iin Riananda Br