The magnetic dipole moment of electrons originates from their orbital and spin degrees of freedom. In magnetism, the macroscopic ordering of magnetic dipole moments is controlled for applications to magnetic recording. On the other hand, spintronics deals with spin-polarized currents for applications to magnetic sensors and magnetoresistive random access memory (MRAM).
In this course, magnetic and spintronic properties of solids are lectured based on quantum mechanics and solid state physics. Fundamental theories of magnetism (paramagnetism, ferromagnetism, antiferromagnetism and ferrimagnetism), and spintronic phenomena (anisotropic magnetoresistance, giant magnetoresistance, tunneling magnetoresistance, anomalous Hall effect, spin Hall effect, and spin injection to semiconductors) will be lectured. Magnetic and spintronic devices (magnetic recording, magnetic sensor, MRAM, semiconductor spintronic device) will be explained.
By the end of this course, students will be able to understand the principles of magnetism and spintronics as the basics of magnetic and spintronic devices, such as magnetic recording, magnetic sensors, and magnetoresistive random access memory (MRAM), and semiconductor spintronic device.
1) Understand fundamentals of magnetism (paramagnetism, ferromagnetism, antiferromagnetism, ferrimagnetism)
2) Understand magnetic anisotropy, magnetic domain and magnetic hysteresis.
３）Understand the anisotropic magnetoresistance effect and its application to magnetic sensor
４）Understand various spin-dependent transport phenomena （giant magnetoresistance, tunneling magnetoresistance, anomalous Hall effect, spin Hall effect）
５）Understand the device structure, operating principle, and materials of magnetoresistive memory (MRAM)
６）Understand the spin-transfer torque phenomenon as a new data writing mechanism of MRAM
７）Understand the concept, device structures and materials of semiconductor spintronics
８）Understand the crystal growth, magnetic properties and future prospects of ferromagnetic semiconductors
Ferromagnets, magnetic recording, magnetic sensor, anisotropic magnetoresistance, giant magnetoresistance, tunneling magnetoresistance, anomalous Hall effect, spin Hall effect, MRAM, ferromagnetic semiconductor
|✔ Specialist skills||Intercultural skills||Communication skills||Critical thinking skills||✔ Practical and/or problem-solving skills|
If there are assignments, their solutions will be reviewed in the first half of the next class.
|Course schedule||Required learning|
|Class 1||Angular momentum of electrons (orbital and spin) as magnetic dipoles||Understanding that angular momentums of electron, such as orbit and spin, are regarded as origins of atomic magnetic dipole moment.|
|Class 2||Magnetic ordering phenomena I (paramagnetism)||Evaluation of a magnitude of magnetic dipole moment of an atom. Considering paramagnetism as the most simple alignment of magnetic dipole moments under a magnetic field.|
|Class 3||Magnetic ordering phenomena II (exchange interaction and ferromagnetism)||Molecular field theory and a consideration of an exchange interaction of electrons as the origin of ferromagnetism.|
|Class 4||Magnetic ordering phenomena III (antiferromagnetism and ferrimagnetism)||Understanding of the anti-parallel alignment of magnetic moments as the origin of anti-ferro and ferrimagnetism.|
|Class 5||Magnetic anisotropy||Variety of magnetic anisotropies of materials and their origins.|
|Class 6||Magnetic domain and magnetization process||Understanding the magnetic domain and technical-magnetization process.|
|Class 7||Spin-dependent scattering phenomenon: anisotropic magnetoresistance effect||Introduction of carrier scattering mechanism based on spin degree of freedom of electrons and the basis of its applications.|
|Class 8||Application of magnetic thin films and particles, magnetic recording and sensors||Characteristics of magnetic thin films and particles for applications to magnetic recording, memories and sensors.|
|Class 9||Spin-dependent transport phenomena I: Giant magnetoresistance effect - Giant magnetoresistance in ferromagnetic metal / non-magnetic metal / ferromagnetic metal artificial lattices||Explain the giant magnetoresistance effect and its microscopic mechanism|
|Class 10||Spin-dependent transport phenomena II: Tunneling magnetoressitance effect - Tunneling magnetoresistance effect in ferromagnet / insulator / ferromagnet magnetic tunnel junctions||Explain the tunneling magnetoresistance effect and its microscopic mechanism|
|Class 11||Spin-dependent transport phenomena III: Anomalous Hall effect and Spin Hall effect - Anomalous Hall effect and spin Hall effect due to intrinsic / extrinsic mechanism||Explain the anomalous Hall effect and spin Hall effect and its microscopic mechanism|
|Class 12||Magnetoresistive memory (MRAM) I: structure and operating principle - MRAM device structure, operating principle, and materials||Explain the device structure, operating principle, and materials of MRAM|
|Class 13||Magnetoresistive memory (MRAM) II: spin-transfer torque - Spin-transfer torque as a new data writing mechnism for MRAM||Explain the spin-transfer torque phenomenon as a new data writing mechanism for MRAM|
|Class 14||Semiconductor spintronics: spin injection into semiconductors , spin transistors, ferromagnetic semiconductors - Introduction to semiconductor spintronics: concept, device structure and materials - Introduction to ferromagnetic semiconductors: crystal growth, magnetic properties and future prospects||Explain the concept, device structures and materials of semiconductor spintronics. Explain the crystal growth, magnetic properties and future prospects of ferromagnetic semiconductors.|
To enhance effective learning, students are encouraged to spend approximately 100 minutes preparing for class and another 100 minutes reviewing class content afterwards (including assignments) for each class.
They should do so by referring to textbooks and other course material.
Charles, Kittel. Introduction to Solid State Physics. John Wiley & Sons, Inc. ISBN-13: 978-0471415268
Chikazumi, Soshin. Physics of Ferromagnetism. Oxford University Press. ISBN-13: 978-0199564811
Stephen, Blundel. Magnetism in Condensed Matter. Oxford University Press. ISBN-13: 978-0198505914
Students will be assessed on their understanding of types of magnetism, spin-dependent scattering and transport phenomena in magnetic materials, and their applications to spintronics. Students’ course scores are based on reports (50%) and exercise problems (50%).
Students must have successfully completed the course "Quantum mechanics(EEE.D201)" or have equivalent knowledge.