# 1st Physics Mini Colloquium

Everyone is invited to the 1st Physics Student Colloquium to be held 12:00-1:30PM on August 6, 2021. This event is hosted by Dr. Jacque Lynn F. Gabayno of the Department of Physics. This features three student works whose topics include thermal physics, ionospheric physics and the Ising model.

Speaker 1:

Title:

Time: 12:00 – 12:30PM

Abstract: Thermal conductivity is the ability of a material to transfer thermal energy. The type of material, density, impurities, and temperature are factors that can affect this property. Metals are known to be good conductors of heat, while nonmetals such as wood or plastic are poor thermal conductors. When atoms inside a material are compact, heat can easily travel. Also, heat flows smoothly when impurities and dislocations are few. Meanwhile, high temperature increases lattice vibrations thereby affecting the thermal conductivity. Although there are many studies on this topic, the dimensional dependence of thermal conductivity needs further understanding. In this study, its dependence on dimensions particularly for 2D and 3D materials will be introduced. To determine the dependence of thermal conductivity with dimension, the Boltzmann transport equation (BTE) and relaxation time approximation (RTA) will be used since the system will be out of equilibrium. Factors contributing to the change of electron distribution will be included to describe how thermal energy is transferred. Moreover, RTA will be used to calculate the relaxation time and determine how far the system deviates from equilibrium. By understanding this, we can improve the thermal conductivity for scaled-down devices used in modern technology which is the goal that drives this study.

**Ms. Althea Marie M. DACANAY**Title:

*A Preview on the Dimensional Dependence of Thermal Conductivity*Time: 12:00 – 12:30PM

Abstract: Thermal conductivity is the ability of a material to transfer thermal energy. The type of material, density, impurities, and temperature are factors that can affect this property. Metals are known to be good conductors of heat, while nonmetals such as wood or plastic are poor thermal conductors. When atoms inside a material are compact, heat can easily travel. Also, heat flows smoothly when impurities and dislocations are few. Meanwhile, high temperature increases lattice vibrations thereby affecting the thermal conductivity. Although there are many studies on this topic, the dimensional dependence of thermal conductivity needs further understanding. In this study, its dependence on dimensions particularly for 2D and 3D materials will be introduced. To determine the dependence of thermal conductivity with dimension, the Boltzmann transport equation (BTE) and relaxation time approximation (RTA) will be used since the system will be out of equilibrium. Factors contributing to the change of electron distribution will be included to describe how thermal energy is transferred. Moreover, RTA will be used to calculate the relaxation time and determine how far the system deviates from equilibrium. By understanding this, we can improve the thermal conductivity for scaled-down devices used in modern technology which is the goal that drives this study.

Speaker 2:

Title:

Time: 12:30 – 1:00 PM

Abstract: Let me take you to a virtual journey of the ionosphere, a layer of the Earth’s atmosphere where electromagnetic signals for navigational satellites such as radio waves propagate. The ionosphere is composed of electrically charged atoms and free electrons, thus the name. Along the path of radio signals from a navigation satellite to a receiver is a dense layer of these electrons, which is called the total electron content (TEC). The upper part of the ionosphere is where the maximum electron density is observed. There are various factors that can affect the electron density of the ionosphere, which consequently affect navigational and electronic signals transmitted to the ground. This talk will provide an overview of various space events that can cause a disturbance to the ionosphere, and their impact to the TEC. These include space weather systems like geomagnetic storms and solar eclipse, which affect the arrival of electrons from the sun into the ionosphere; and atmospheric phenomena due to hurricanes or thunderstorms, which then ripple up into the ionosphere. Strong perturbations of the electron density due to these events may cause adverse effects on the safety of life that depends on navigation infrastructures such as aircrafts, satellite imaging, and even satellite launches.

**Mr. Acezhare Angelo V. DOCABO**Title:

*Meta-Analysis on the Effects of Ionospheric Total Electron Content (TEC) Disturbances to Navigational Systems*Time: 12:30 – 1:00 PM

Abstract: Let me take you to a virtual journey of the ionosphere, a layer of the Earth’s atmosphere where electromagnetic signals for navigational satellites such as radio waves propagate. The ionosphere is composed of electrically charged atoms and free electrons, thus the name. Along the path of radio signals from a navigation satellite to a receiver is a dense layer of these electrons, which is called the total electron content (TEC). The upper part of the ionosphere is where the maximum electron density is observed. There are various factors that can affect the electron density of the ionosphere, which consequently affect navigational and electronic signals transmitted to the ground. This talk will provide an overview of various space events that can cause a disturbance to the ionosphere, and their impact to the TEC. These include space weather systems like geomagnetic storms and solar eclipse, which affect the arrival of electrons from the sun into the ionosphere; and atmospheric phenomena due to hurricanes or thunderstorms, which then ripple up into the ionosphere. Strong perturbations of the electron density due to these events may cause adverse effects on the safety of life that depends on navigation infrastructures such as aircrafts, satellite imaging, and even satellite launches.

Speaker 3:

Title:

Time: 1:00 – 1:30 PM

Abstract: Ising model is a simple but very useful model in demonstrating phase transition in ferromagnetic materials. Ernst Ising solved the exact solution to phase transition in 1-dimensional (1-D) Ising model and found that there is no such phase transition, and also claimed that there will be no phase transition in higher dimensions. Lars Onsager’s have proved a solution to the existence of phase transition in a 2-D square Ising model contrary to Ising’s claims. The solutions of Ising and Onsager showed that there is a difference in the critical behavior in the Ising model in different dimensions. The objective of this study is to investigate the effects of dimensionality in the critical phenomena by simulating the phase transition of the Ising model. Using the Metropolis Algorithm, a Markov chain Monte Carlo, the spontaneous magnetization of a ferromagnetic material will be demonstrated. By putting the Ising spin system into a heat bath, the spins will flip back and forth due to the increased temperatures. The phase transition will be observed using the Curie-Weiss Law in which the magnetic susceptibility is asymptotic to the critical point. The magnetic susceptibility of the system will be obtained from the total magnetization of the spins. The algorithm will be implemented with changing dimensionality to demonstrate the effects of dimension in the critical behavior of the Ising spin system.

**Mr. Dustin Jireh L. SUNGA**Title:

*Critical Behavior of 1-D to 2-D Transition Ising Model Using Metropolis Algorithm*Time: 1:00 – 1:30 PM

Abstract: Ising model is a simple but very useful model in demonstrating phase transition in ferromagnetic materials. Ernst Ising solved the exact solution to phase transition in 1-dimensional (1-D) Ising model and found that there is no such phase transition, and also claimed that there will be no phase transition in higher dimensions. Lars Onsager’s have proved a solution to the existence of phase transition in a 2-D square Ising model contrary to Ising’s claims. The solutions of Ising and Onsager showed that there is a difference in the critical behavior in the Ising model in different dimensions. The objective of this study is to investigate the effects of dimensionality in the critical phenomena by simulating the phase transition of the Ising model. Using the Metropolis Algorithm, a Markov chain Monte Carlo, the spontaneous magnetization of a ferromagnetic material will be demonstrated. By putting the Ising spin system into a heat bath, the spins will flip back and forth due to the increased temperatures. The phase transition will be observed using the Curie-Weiss Law in which the magnetic susceptibility is asymptotic to the critical point. The magnetic susceptibility of the system will be obtained from the total magnetization of the spins. The algorithm will be implemented with changing dimensionality to demonstrate the effects of dimension in the critical behavior of the Ising spin system.

This event will be conducted via Zoom:

Meeting ID: 988 1003 9203

Passcode: 393070

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Meeting ID: 988 1003 9203

Passcode: 393070

♦