Q4(Graduation Research) “Superconductivity and magnetism”

Kenji Ishida, Shingo Yonezawa, Shunsaku Kitagawa
Teaching Assistant (TA)

  • Introduction
  • Schedule
  • Seminar
  • Experiment content
  • Members and graduation thesis titles

Introduction

In this project, we will study various phenomena that many electronic systems show, such as superconductivity and spin order.

The first half of the year will focus on seminars for understanding the fundamentals of superconductivity, such as Bardeen-Cooper-Schrieffer (BCS) theory.

In the latter half, we chose our own research themes and synthesized materials that exhibit various superconductivity and magnetic properties, including spin triplet superconductors, and we developed specific heat at low temperatures, electrical resistivity, magnetic susceptibility, and nuclear magnetic resonance (NMR). ), Etc., and aim to understand their quantum physical properties.

In each case, each student can study along with his or her own graduation thesis theme, and at the same time, challenge themes that include the part where the answer is not known to anyone. During my graduation research, my goal is to have the students yell at me at least once.

Schedule

JuneSmall presentation
September(after the examination)Experiments start
DecemberInterim presentation
~ February 10Final presentation
~ February 12Deadline for graduation thesis version 1

Seminar

In the weekly seminar, you will learn the basic properties of superconductivity, Bardeen-Cooper-Schrieffer (BCS) theory, Ginzburg-Landau theory, etc. using superconducting textbooks. It will be a learning that comprehensively applies knowledge of quantum mechanics, statistical thermodynamics, and electromagnetics.

The textbooks I have used so far are:

[First half] Hiroyuki Shiba, “Electron theory of solids” (Morikita, 2019).
[Second half] Textbook of magnetism or superconductivity.

Research Theme

In conducting research, there are some themes with a little emphasis on sample synthesis and some with a focus on the production of measuring devices. Examples of recent themes include spin triplet superconductivity research, topological insulator / superconductor research, and heavy electron-based materials and iron-based superconductor-related materials. With either theme, you can get a little touch on the latest research on superconductivity and magnetic materials.

In sample synthesis, we will challenge the growth of single crystals using infrared heating furnaces and the challenge of synthesizing new materials using various synthesis furnaces.

Most of the measurements are low-temperature experiments using liquid helium. As equipment, we also use a helium 3 refrigerator that can cool to 0.3 K and a helium 3-helium 4 dilution refrigerator that can cool to 10 mK. In addition, there are also themes including the production of super-sensitive magnetization measurement devices using superconducting quantum interference devices (SQUIDs) and sample rotation devices using piezo elements. Then, through the measurement of electrical resistivity, magnetic susceptibility, specific heat, nuclear magnetic resonance, etc., we will explore various quantum properties of superconductors and magnetic materials.