Articles

Found 18 Documents
Search

Theoretical Exposition of A Single Electron Quantum Dot T. Cahyanto, Wahyu; Abraha, Kamsul; Nurwantoro, Pekik
IPTEK The Journal for Technology and Science Vol 18, No 2 (2007)
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (348.872 KB) | DOI: 10.12962/j20882033.v18i2.174

Abstract

This paper will review atomic-like phenomena in a semiconductor quantum dot which their size, shape and interactions can be precisely controlled through the use of nanofabrication technology. It has been shown that by confining electrons in three dimensions inside semiconductors, quantum dots can show many of the phenomena observed in atoms and nuclei and so called artificial atom. Because of its controlable system, it is possible to explore the correlation effects in regimes that cannot otherwise be accessed in other physical systems. For simplicity, this work will focus on a circular-shape single electron quantum dot trapped by polar two-dimensional harmonic potential in the presence of an external magnetic field. Both Zeeman splitting and spin orbit interaction are neglected in our calculation. The calculation show that Fock-Darwin spectrum will enter Landau regime, where when cyclotron frequency is much larger than potential confinement .
Optimization of The Mechanical Drive on Set-up of Homemade Surface Plasmon Resonance Arifin, Muhammad; Laksono, Febrilian Dwi; Supardianningsih, Supardianningsih; Abraha, Kamsul
Journal of Physics: Theories and Applications Vol 1, No 2 (2017): Journal of Physics: Theories and Applications
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/jphystheor-appl.v1i2.19124

Abstract

Mechanical optimization has been done on the surface plasmon resonance (SPR) homemade. At set-up, angle scanning comes a small resolution to detect changes in the thickness of the thin film or refractive index of the sample. The mechanical drive has a function to rotate the prism and detector. Torsional Spring-Loaded Gear Antibacklash is used to improve the accuracy of the mechanical drive. The stepper motor is used to rotate the mechanical drive automatically. The built system has successfully increased the resolution of the prism rotation angle by 0.01°. The test using the blank prism indicates the angle of Total Internal Reflection occurs at an incident angle of 41.80 °. The SPR phenomenon was observed in a thin layer of gold deposited on the prism using a vacuum evaporator. The observed SPR angles on samples A, B, C, D, E, F, G, H and I were 45.02°, 45.05°, 46.30°, 44.48°, 44.70°, 45.49°, 45.52°, 45.66°, and 44.44°, respectively. The SPR angle change shows the difference in the thickness of the gold thin film.
GIANT MAGNETORESONANCE EFFECT OF NiFe/Ag/ NiFe MULTILAYERS PREPARED WITH DC SPUTTERING TECHNIQUE ON Ag DEPOSITION TIME Toifur, Mohammad; Abraha, Kamsul; Ridwan, .
Berkala Fisika Indonesia Vol 2, No 1: July 2009
Publisher : Pasca Sarjana Pendidikan Fisika Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (21.219 KB)

Abstract

A study on the Giant Magnetoresonance (GMR) effect of NiFe/Ag/NiFe multilayers on  Ag deposition time (tAg) ranging from 1 to 3 minutes has been performed. The study was intended  to obtain the most suitable Ag deposition time to give the largest GMR ratio by using 150 G deposition field in transverse direction of anode-chathde and C substrate temperature during deposition. Several characterizations have been performed  including morphological sample cross section,  microstructure, magnetic properties of the layer, and GMR ratio in an external magnetic field  ranging from -20 up to 20 gauss. The results show that multilayers with tag = 2 minutes displays the largest GMR ratio of 54.87%. The layer has a high level of atomic structure ordering, a large grain size, the highest remanence and the smallest coercive power. The situation is close to Pool’s estimation that the GMR ratio for trilayers of approximately 50%.
Purity Testing of Cultivar Melon DNA Level (Cucumis melo L.) “Gama Melon Basket” using Surface Plasmon Resonance (SPR) Based on Silver Nanoparticle T, Thoyibi; Arifin, Muhammad; Abraha, Kamsul
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 5, No 01 (2015): IJAP Volume 05 Issue 01 Year 2015
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v5i01.254

Abstract

DNA level of purity has been tested by observing the phenomenon of surface plasmon resonance (SPR) in silver film + silver (Ag) nanoparticles system as DNA sensor using Kretschmann configuration. Surface plasmon resonance (SPR) phenomenon observed in the resonance condition of reflectance spectrum vary with incident angle of laser, beamed toward prism. System is built as a model for DNA purity test instrument that give higher accuracy. DNA purity testing was conducted by placing DNA layer with various ratio on prism in order to get the angle shift value in each sample as a result. Purity level of DNA indicates the DNA quality based on the ratio between the amount of pure DNA compared to the amount of impurity materials (protein). After the deposition of DNA in ratio 1,774, 1,838 and 1,916 SPR angle shifted ,  and  respectively. Characteristic differences of DNA with different purity (ratio) are shown by reflectance value that is getting higher at a smaller ratio, indicates that in the higher DNA ratio the angle shift is getting smaller. SPR angle shift which is occurred before and after DNA deposition shows the sensitivity of SPR as DNA sensor.
Kajian Pengaruh Penambahan Nanopartikel Perak (AgNPs) Terhadap Respon Instrumen Sensing Berbasis Surface Plasmon Resonance (SPR) Arifani, Tyas; Abraha, Kamsul
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 3, No 01 (2013): IJAP VOLUME 03 ISSUE 01 YEAR 2013
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v3i01.1214

Abstract

Theoretical studies have been done related to the phenomenon of surface plasmon resonance (SPR) on the system with addition of silver nanoparticles (AgNPs) that was modeled as a sensing instrument. Model is built with AgNPs placed as an additional layer over the conventional SPR system. Quantitative analysis on the model will provide a response in the form of reflectance spectrum as a function of incident angle that showed SPR angle ( SPR ) point and the attenuation. To know how the AgNPs in various sizes affect the resonance coupling, it will be calculated the dispersion relation curves obtained as the solution of Maxwell’s equations. Coupling between surface plasmon wave and evanescent wave will provide the resonance angle on the intersection of the two curves. Computational analysis of ATR method, demonstrate how the addition of AgNPs in sensing instrument configuration will improve performance of such instruments, visualized by SPR angle shift.
THE POTENTIAL OF IRON SAND FROM THE COAST SOUTH OF BANTUL YOGYAKARTA AS RAW CERAMIC MAGNET MATERIALS Rusianto, Toto; Wildan, M. Waziz; Abraha, Kamsul; Kusmono, Kusmono
Jurnal Teknologi Vol 5 No 1 (2012): Jurnal Teknologi
Publisher : Jurnal Teknologi, Fakultas Teknologi Industri, Institut Sains & Teknologi AKPRIND Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (495.616 KB)

Abstract

Magnet merupakan bahan teknik yang kebutuhannya meningkat seiring dengan meningkatnya perkembangan industri elektronika di Indonesia, akan tetapi kebutuhan magnet di Indonesia masih diimpor dari luar negeri. Sementara bahan baku magnet berupa besi oksida tersedia cukup banyak di Indonesia, salah satunya pasir besi di pantai Selatan Yogyakarta. Pasir besi mengandung sifat magnetik karena adanya mineral magnetite (Fe3O4) berwarna hitam, maghemite  ( -Fe2O3), Rutil (FeTiO3), yang besifat magnetik. Mineral magnetit dapat dikembangkan menjadi bahan magnet contohnya untuk pita magnetik, magnet speaker, magnet motor listrik dan lain-lain. Pasir besi di pantai selatan Bantul Yogyakarta berwarna abu-abu kehitaman menunjukan adanya kandungan material magnetik dalam jumlah besar. Hasil pengujian dengan menggunakan magnet, rata-rata 66.32% berat menempel pada magnet, dari hasil tersebut dilakukan pemisahan dengan metode sieving persentase jumlah terbesar sebanyak 32% pada ukuran bukaan <+212 m. Pengujian dilakukan pada pasir yang menempel pada magnet dan hasil sieving pada jumlah terbesar. Hasil karakteristik material magnetik menggunakan Vibrating Sample Magnetometer (VSM), menunjukan saturation magnetisation (Ms) adalah 13,18 emu/gr dan 36,49 emu/gr, magnetik remanen (Mr) 4,15 emu/gr dan 7,95 emu/gr, koersivitas (Hc) 230 Oe dan 186 Oe, suseptibilitas massa ( ).1,45 ?10-4 m3/kg dan 4,31 ?10-4 m3/kg. Hasil uji XRD menunjukan dominasi magnetite dan maghemite pada pasir besi. Berdasarkan kajian tersebut, bahwa pasir pantai Selatan Bantul Yogyakarta merupakan material magnetik. Material mangetik yang terkandung pada pasir pantai memiliki potensi sebagai bahan keramik magnet (MO.xFe2O3).  
TELAAH TEORITIS BAK-ATOM QUANTUM DOT SEMIKONDUKTOR DALAM MEDAN MAGNET LUAR Cahyanto, Wahyu Tri; Abraha, Kamsul; Nurwantoro, Pekik
Berkala Ilmiah MIPA Vol 16, No 3 (2006)
Publisher : FMIPA UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Analytical calculation on the atomic-like phenomena is presented in a semiconductor quantum dot trapped by two-dimensional harmonic potential in the presence of a homogeneous magnetic field. The calculation neglects both Zeeman splitting and spin orbit interaction. This paper is proposed as the first sight of advanced research on nanotechnology in Indonesia. Many of the phenomena observed in atoms and nuclei are also observed in the semiconductor quantum dot which is then called an artificial atom. It has been shown that atomic shells can be described by a set of degenerated energy levels filled by 2, 6, 12, ... electrons known as “magic numbers”. The results of the calculations show that the Fock-Darwin spectrum will enter Landau regime when its cyclotron frequency (fc) is much larger than the frequency associated with the potential confinement (fo). Keywords: Semiconductor quantum dot, Electron confinement, Shell structure, Artificial atom
PENENTUAN KURVA DISPERSI TEORITIS POLARITON MAGNETIK PERMUKAAN DALAM BAHAN MAGNETOELEKTRIK Malahayati, -; Abraha, Kamsul
Berkala Ilmiah MIPA Vol 16, No 2 (2006)
Publisher : FMIPA UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Telah ditentukan secara teoritis kurva dispersi polariton magnetik permukaan bahan magnetoelektrik uniaxial dua subkekisi BaMnF4 dalam daerah frekuensi 0-50 cm-1, dengan perambatan gelombang tegak lurus pada sumbu mudah tanpa medan luar. Relasi dispersi tersebut diperoleh melalui persamaan-persamaan Maxwell untuk medium magnetoelektrik dengan penerapan syarat batas bagi komponen medan listrik dan magnetnya. Suseptibilitas listrik, magnetik dan magnetoelektrik bahan adalah besaran-basaran yang mengatur dinamika internal sistem magnetik tersebut. Telah ditunjukkan bahwa polariton magnetik permukaan tidak merambat dalam TM (Transverse Magnetic) tapi hanya merambat dalam ragam TE (Transverse Electric) yang bersifat nonresiprokal dengan perubahan arah vektor gelombang menyebabkan perubahan frekuensi atau ω (q ) ≠ ω( −q ) . Ditemukan dua jenis polariton magnetik permukaan, yaitu yang memiliki frekuensi batas magnetostatik (real mode) dan yang tidak memiliki batas magnetoelektrik (virtual mode). Kedua jenis polariton tersebut tidak terpengaruh oleh efek magnetoelektrik. Sebagai tambahan ditemukan polariton limbak dalam ragam TM yang dapat terpengaruh oleh adanya interaksi magnetoelektrik dalam bentuk munculnya ragam magnon polariton dan phonon polariton pada frekuensi tertentu. Untuk menunjukkan keberadaan polariton permukaan dilakukan pula perhitungan reflektivitas ATR (attenuated total reflection) yang ternyata dapat terdeteksi pada saat jarak antara prisma dan cuplikan mencapai nilai optimum sebesar 0,2 cm. Reflektivitas ATR dari virtual mode dapat diperoleh dengan menggunakan prisma Si(dengan tetapan dielektrik ep = 11.56), sedangkan untuk real mode diperoleh dengan e lebih besar (ep > 17) yang tentu saja belum dapat dilakukan karena belum ditemukan prisma dengan nilai ep sebesar itu. Kata kunci: Polariton Magnetik, Bahan Magnetoelektrik
THE POTENTIAL OF IRON SAND FROM THE COAST SOUTH OF BANTUL YOGYAKARTA AS RAW CERAMIC MAGNET MATERIALS Rusianto, Toto; Wildan, M. Waziz; Abraha, Kamsul; Kusmono, -
Jurnal Teknologi Vol 5, No 1 (2012)
Publisher : Jurnal Teknologi

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

The demand of magnets increases with the increasing development of electronic industry in Indonesia, but it was still imported from abroad. While the magnetic materials as iron oxide are quite a lot in Indonesia, one of deposits area  of iron sand  is Southern  coast of Bantul Yogyakarta. The sand contained of the mineral magnetic, these minerals were magnetite (Fe3O4) is black color, maghemite ( -Fe2O3). Mineral magnetite can be developed as a magnet, example of magnetic material for magnetic tape, magnetic speaker, magnet electric motors and others. Iron sand at southern coast of Bantul Yogyakarta is blackish gray color indicates that it contains large amounts of magnetic material. The results of research by using a magnet, average 66.32% of weight attracted to magnet permanent. The results of the separation is carried out by sieving method the largest percentage of 32% at opening size <+212 m. Characterizations of magnetic materials using Vibrating Sample Magnetometer (VSM) and XRD have done on the sand that attracted to the magnet and sieving result. The result by VSM showed that saturation magnetization (Ms) are 13.18 emu/g and 36.49 emu/g, remanent magnetic (Mr) 4.15 emu/g and 7.95 emu/g, coercivity magnetic (Hc) 230 Oe and 186 Oe, susceptibility mass ( ) 1.45 × 10-4 m3/kg and  4.31 × 10-4 m3/kg. XRD analysis indicates that the iron sand were dominated magnetite and maghemite minerals. Based on this analysis, the sands of Southern coast in Bantul Yogyakarta can be used as magnetic material. Magnetic material contained on the coast sand has potential as ceramic magnet permanent materials (MO.xFe2O3).Keywords: magnet, magnetite, saturation magnetization, susceptibility, iron sand
Ketergantungan Mobilitas pada Temperatur Pengukuran Lapisan Porphyrin Alam Fatmawati, Elly; Utari, Utari; Purnama, Budi; Abraha, Kamsul
Jurnal Fisika dan Aplikasinya Vol 10, No 3 (2014)
Publisher : Jurnal Fisika dan Aplikasinya

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (237.212 KB) | DOI: 10.12962/j24604682.v10i3.792

Abstract

Efek temperatur terhadap mobilitas lapisan porphyrin alam diproduksi dengan metode deposisi spin coating di atas substrat Cu didiskusikan. Analisis pembawa muatan dilakukan dengan menggunakan metode pengukuran I-V dari temperatur T = 20C hingga T = 23C. Hasil eksperimen menunjukkan bahwa efek agitasi thermal meningkatkan arus terukur. Mobilitas meningkat secara linier dengan kenaikan temperatur pengukuran. Akhirnya, respon kenaikan nilai mobilitas terhadap temperatur pada sampel dengan N = 14 lebih cepat dibandingkan N = 8.