Nonlinear Anomalous Nernst Effect in Noncentrosymmetric Tungsten Ditelluride

Abdurrafi A. Alghifari ^1,2, Muhammad Y. Hanna ¹, Edi Suprayoga ¹∗, and Moh. Adhib Ulil Absor ²

1. Research Center for Quantum Physics, BRIN
2. Department of Physics, UGM

*edi.suprayoga [at] brin.go.id

The generation of anomalous Thermoelectric effect in nonmagnetic materials has garnered
much attention due to the advancement of topological materials. One of the materials showing a large unconventional Thermoelectric effect is the predicted Type-II Weyl Semimetal Tungsten Ditelluride. This study attempts to explain the large value of anomalous Nernst effect in Tungsten Ditelluride via the breaking of inversion symmetry. In spite of the absence of magnetization and external field, the non-centrosymmetric Td-WTe2 bilayer shows a strong Berry Curvature of 1000 A, reveals a large enhancement up to 10^4 times greater than its centrosymmetric monolayer configuration. This ultimately results in the significant value of anomalous Nernst coefficient in Tungsten Ditelluride up to 1 μV/K in 100 Kelvin, comparable to previous reported value from other magnetic materials. Hence, we demonstrated the key role of breaking inversion symmetry in the thermoelectric properties
of the non-centrosymmetric Tungsten Ditelluride.

Dual-Atom Iron Electrocatalyst for Enhanced Oxygen Reduction Reactions

Joel F. Sumbowo ^1,2, Farhan A. Ihsan ^1,2, Fadjar Fathurrahman ^2,3, Nadya Amalia ¹, Fiki T. Akbar ⁴, Hadi T. Yudistira ⁵, Nadhratun N. Mobarak ⁶, Hermawan K. DIpojono ^2,3, Sasfan A. Wella ^1,7*, and Adhitya G. Saputro ^2,3

1. Research Center for Quantum Physics, National Research and Innovation Agency (BRIN), South Tangerang 15314, Indonesia.
2. Advanced Functional Materials Research Group, Faculty of Industrial Technology, Institut Teknologi Bandung, Bandung 40132, Indonesia.
3. Research Center for Nanosciences and Nanotechnology, Institut Teknologi Bandung, Bandung 40132, Indonesia
4. Theoretical High Energy Physics Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Bandung 40132, Indonesia
5. Mechanical Engineering Study Program, Institut Teknologi Sumatera (ITERA), South Lampung 35365, Indonesia
6. Department of Chemical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia
7. Collaboration Research Center for Advanced Energy Materials, Bandung 40132, Indonesia

*sasfan.arman.wella [at] brin.go.id

Pyrolyzed Fe-N-C catalysts, especially FeN_4, are known for their enhanced catalytic activity, particularly in oxygen reduction reactions (ORR). This study presents a computational analysis of a different Fe-N-C catalyst, Fe_2N_6, adsorbed on graphene, with a focus on graphene nanoribbon edges (zig-zag and armchair) as potential Fe dual-atom catalysts (Fe-DACs). Using density functional theory and microkinetic simulations, we explore the impact of graphitic edges on the stability and ORR activity of Fe-DAC sites. Our results show that zig-zag edges notably reduce the formation energy of Fe-DAC sites, making them more likely to form at these edges. Additionally, several Fe-DAC sites at graphitic edges demonstrate better ORR performance, outperforming the widely used FeN_4 site in single-atom catalyst systems and even surpassing the state-of-the-art Pt(111) catalyst. The (Fe_2N_6)_o@z_1 site, in particular, exhibits exceptional performance in both associative and dissociative mechanisms. These findings underscore the importance of graphitic nanopores in enhancing Fe-DAC catalytic behavior, offering insights for the development of efficient non-precious metal catalysts for ORR applications.

Atomic Asymmetry Effects in 2D Janus Materials

Nadya Amalia ¹*, Harry H. Halim ², Elfi Yuliza ¹, Wilin J. Sari ³, Sasfan A. Wella ¹

1. Research Center for Quantum Physics, National Research and Innovation Agency (BRIN), Indonesia
2. Department of Precision Engineering, Graduate School of Engineering, Osaka University, Japan
3. Research Center for Climate and Atmosphere, National Research and Innovation Agency (BRIN), Indonesia

*nadya.amalia [at] brin.go.id

Two-dimensional (2D) materials are widely studied for their distinct properties and broad applications. Among these, Janus materials have gained interest due to their unique asymmetric atomic structure. In these materials, the two sides of the monolayer are composed of different elements, such as S, Se, and Te. This broken mirror symmetry leads to specific structural and electronic properties.

In this study, we investigate the structural and electronic properties of CrXY Janus materials (X, Y = S, Se, Te) using first-principles density functional theory (DFT) calculations. Our analysis shows that atomic asymmetry causes variations in lattice parameters and bond characteristics, influencing the material’s stability. The broken mirror symmetry also generates an intrinsic electronic field, which impacts the electronic behavior of the material, as reflected in the electronic band structure and density of states (DOS).

Our findings provide insights into how atomic asymmetry shapes the structural and electronic properties of 2D Janus materials, contributing to a broader understanding of these systems.

High-performance quantum battery with non-linearities

MS Ukhtary ^1,2*, CA Downing ², ART Nugraha ¹, AB Cahaya ³, A Rusydi ⁴, A Majidi ³

1. National Research and Innovation Agency (Indonesia)
2. Univ. of Exeter (United Kingdom)
3. Univ. of Indonesia (Indonesia)
4. National Univ. of Singapore (Singapore)

*msho001 [at] brin.go.id

Quantum battery (QB) is defined as a quantum system that can store energy. The main problem to tackle in QB is to achieve more stored energy with faster charging time. In this work, we consider a model of QB with nonlinearity effect: Kerr nonlinearity and quadratic driving. We show by adding nonlinearity to the system, the performance of the quantum battery in terms of stored energy and charging time becomes better. The Kerr nonlinearity induces anharmonicity in the energy levels of the battery. On the other hand, quadratic driving leads to a squeezed quantum battery, which generates plentiful useful energy near to critical points.

Tunable optical absorption in undoped graphene sandwiched between multilayer dielectric stacks with mirror symmetry

Faisal Kengo ^1,2, S Solihin ^1,3, M Shoufie Ukhtary ¹, Joko Suwardy ¹, M Aziz Majidi ², Ahmad R T Nugraha ^1,4,5*

1. Research Center for Quantum Physics, National Research and Innovation Agency (BRIN), South Tangerang 15314, Indonesia
2. Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok 16424, Indonesia
3. Department of Physics, Faculty of Science and Data Analytics, Institut Teknologi Sepuluh Nopember, Surabaya 60111, Indonesia
4. Department of Engineering Physics, Telkom University, Bandung 40257, Indonesia
5. Research Collaboration Center for Quantum Technology 2.0, Bandung 40132, Indonesia

∗ahmad.ridwan.tresna.nugraha [at] brin.go.id

We investigate the optical absorption of an undoped graphene monolayer when it is put in a one-dimensional multilayer stack. Using the transfer matrix method, we derive explicit formulas for the optical absorption of the graphene monolayer at the center of the dielectric stack and find that the optical absorption uniquely depends on repetition number r and the unit layers structure. When sandwiched between unit layers structure composed of three
dielectric materials (referred to as the “ABC” structure) with even values of r, the graphene monolayer absorbs 2.3% of visible to near-infrared light. This behavior is the same as if graphene were free-standing, not sandwiched between the dielectric stack. In contrast to that situation, in the ABC structure with odd values of r, also when the graphene monolayer is sandwiched between four materials (the “ABCD” structure) with any values of r, we can obtain optical absorption as large as 50% at particular refractive indices n of the constituent dielectric materials. The 50%-absorption is, in fact, the maximum optical absorption for any undoped monolayer material in the symmetric dielectric stacks. By varying r and n within the ABC or ABCD structures, we can finely adjust the optical absorption of graphene within the range of 0–50%, facilitating precise control for various optoelectronic applications

Effect of Scattering Rate and Thickness Variation on the Propagation of Surface Plasmon Polariton (SPP) in Topological Weyl Semimetals Waveguide

N S Utami ¹*, M A Majidi ¹*, M S Ukhtary ²*, A Budiyono ²

1. University of Indonesia
2. Research Center for Quantum Physics, National Research and Innovation Agency (BRIN)

*nuriseptiautami [at] gmail.com

The generation of anomalous Thermoelectric effect in nonmagnetic materials has garnered
much attention due to the advancement of topological materials. One of the materials showing a large unconventional Thermoelectric effect is the predicted Type-II Weyl Semimetal Tungsten Ditelluride. This study attempts to explain the large value of anomalous Nernst effect in Tungsten Ditelluride via the breaking of inversion symmetry. In spite of the absence of magnetization and external field, the non-centrosymmetric Td-WTe2 bilayer shows a strong Berry Curvature of 1000 A, reveals a large enhancement up to 10^4 times greater than its centrosymmetric monolayer configuration. This ultimately results in the significant value of anomalous Nernst coefficient in Tungsten Ditelluride up to 1 μV/K in 100 Kelvin, comparable to previous reported value from other magnetic materials. Hence, we demonstrated the key role of breaking inversion symmetry in the thermoelectric properties
of the non-centrosymmetric Tungsten Ditelluride.

Study of the Six-Dimensional Potential of Two-Electron System Ground State Energy with Neural Network

Achmad Jaelani ¹, Yanoar Pribadi Sarwono ²*, Muhammad Aziz Majidi ¹

1. Universitas Indonesia
2. National Research and Innovation Agency (BRIN)

*yano001 [at] brin.go.id

In this study, we address the challenge of predicting the ground state energy of a two-electron system using a deep neural network. We generate a dataset by solving the Schrödinger equation for a two-electron system and then train a convolutional neural network to predict the ground state energy based on a six-dimensional potential representation. Within a relatively small grid space, our predictions for the ground state energy closely match the exact values. Our results highlight the promising potential of deep learning in managing multi-electron systems.

Thermoelectric Properties of Type-I and Type-II Nodal Line Semimetals: A Comparative Study

Mohammad Norman Gaza Laksono ¹*, M. Aziz Majidi ², ART Nugraha ¹

1. Research Center for Quantum Physics, National Research and Innovation Agency (BRIN),  South Tangerang 15314, Indonesia;
2. Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok 16424, Indonesia

*norman.gaza [at] gmail.com

We investigate the thermoelectric (TE) properties of Nodal Line Semimetals (NLSs) using a combination of semi-analytical calculations of Boltzmann’s linear transport theory with the relaxation time approximation, along with first-principles calculations for type-I (type-II) NLS. We consider these materials’ conduction and valence bands that cross near the Fermi level from the band structure obtained through first-principles calculations by using the two-band model through fitting to find the initial value of energy dispersion parameters for each energy band from both types of the material, namely Fermi velocity $v_{F}$ and effective mass $m$. We try to find the optimum curvature value for each energy band by tuning those parameter values to improve its TE Properties. Our calculation results show that for type-I NLS we obtain $\sim3.5\%$ increase of Seebeck coefficient peak value compared to those using initial parameter value from $0.509S_{0}$ to $0.527S_{0}$ when $m=0.2m_{0}$ where $S_{0} = k_{B}/e \approx 86.17 \,\, \upmu \mathrm{V/K}$. Meanwhile, for type-II NLS we obtain a $\sim83\%$ in power factor when $v_{F}$ is lowered. In addition, by comparing all of our calculation results, we observed that tuning $v_{F}$ has a more significant impact on improving TE properties in both type of NLS compared to tuning $m$. We believe our work can trigger similar calculations on other materials in order to scan the TE potential of the materials by manipulating the band structure by varying the curvature of its energy band.

Optimization of TiO₂-Eggshell Composite for Enhanced Photocatalytic Degradation of Methylene Blue

Rahmawati Munir ¹*, Dadan Hamdani ¹, dan Sahara Hamas Intifadhah ¹

1. Theoretical and Material Physics Laboratory, Department of Physics, Mathemathics and Natural Science, Mulawarman University, Jl. Barong Tongkok No. 4, Samarinda, Kalimantan Timur, 75123

*rahmawati [at] fmipa.unmul.ac.id

This research explores the synthesis and application of eggshell powder (ESP) composite with titanium dioxide (TiO₂) in water purification efforts through the degradation of methylene blue (MB). The CT-TiO₂ composite material was synthesized using the Solid State Dispersion (SSD) method. Testing showed that an increase in MB concentration led to an increase in absorbance on the UV-VIS Spectrophotometer, with the optimum mass found in the CT sample with 2% TiO₂ (CT-2%TiO₂). All composite samples exhibited MB degradation efficiency of over 95%, indicating the high capability of the composite in MB photodegradation with UV light. Additionally, the use of CT-TiO₂ composite also increased the solution’s pH from 6.72 to 7.91. These results affirm the potential of CT-TiO₂ composite as an effective and environmentally friendly solution for purifying water contaminated with methylene blue, improving water quality while optimizing pH parameters for broader applications.

Enhancing airless tire performance for military vehicles: natural rubber compound with carbon black Fillers N220 and N550 with dynamic mechanical analysis approach

Riri Murniati ^1,2*, Arini Fitria Gunawan ², Ade Sholeh Hidayat ¹, Liszulfah Roza ¹, Dewi Kusuma Arti ¹ Indriasari ¹, Akhmad Amry ^1,2, Mikrajuddin Abdullah ³

1. Advanced Materials Research Center, National Research and Innovation Agency (BRIN), Banten 15314, Indonesia
2 Study Program of Physics, Indonesia Defense University, IPSC Sentul, Bogor 16810, Indonesia
3 Department of Physics, Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40132, Indonesi

*ririmurniati90 [at] gmail.com

During and after the COVID-19 pandemic, the world has become more aware of environmental concerns and the importance of sustainability. Using natural rubber instead of synthetic rubber is one step toward a greener environment in a variety of technological applications, including the fabrication of vehicle tires. The objective of this work is to optimize the formulation for the production of airless tires, primarily for military vehicle applications, using natural rubber. Two natural rubber types, SIR 20 and RSS 1, with carbon black variants N220 and N550 as reinforcing agents present novel synergistic efects, and potentially tailor the properties of the rubber compound more precisely to meet the demanding requirements of military vehicle tires. A comprehensive assessment was conducted to evaluate various physical, damping, processing, and mechanical properties under standard conditions and subsequent aging at 70 °C for 72 h. Comparative analysis against control samples revealed notable improvements, particularly in abrasion resistance, crucial for tire wear. The combination of RSS 1 and CB N220 showed signifcant enhancements in strength and rigidity, suggesting their viability as alternative fllers. Leveraging dynamic mechanical analysis (DMA) results, the rubber compound underwent optimization to meet airless tire requirements, encompassing durability, comfort, and performance. This nuanced understanding of rubber’s viscoelastic behavior holds paramount importance in designing puncture-resistant airless tires with optimal performance attributes. Combination of innovative materials and advanced characterization techniques to address the specifc challenges of enhancing airless tire performance for military vehicles in challenging operational environments.

Keywords: Non-pneumatic tires · Vulcanized Carbon Fillers · Viscoelastic damping · Dynamic mechanical analysis (DMA) · Defense Applications