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Nanoelectronics. Lecture 9 Magnetics and Spintronics Qiliang Li. Ferromagnetic Materials. Any material that could exhibit spontaneous magnetization: a net magnetic moment in the absence of an external magnetic field. Completely polarized or partially polarized
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Nanoelectronics Lecture 9 Magnetics and Spintronics Qiliang Li Q.Li@GMU@2019
Ferromagnetic Materials Any material that could exhibit spontaneous magnetization: a net magnetic moment in the absence of an external magnetic field Completely polarized or partially polarized Antiferromagnetic: opposing moments completely balance Q.Li@Physics.WHU@2015.3
Magnetic hard drive Q.Li@Physics.WHU@2015.3
Spintronics • Spintronics: the study of control and manipulation of electron spins in a solid-state system for logic, memory and sensor applications. Q.Li@Physics.WHU@2015.3
ferromagnet/insulator/ferromagnet (F/I/F) tunnel junction I. Zutic, J. Fabian and S. Das Sarma, “Spintronics: Fundamentals and applications” Rev. Mod. Phys. 76, 223(2004) Q.Li@Physics.WHU@2015.3
Electron Tunneling Magnetoresistance (TMR) Q.Li@Physics.WHU@2015.3
Spin injection Electrical spin injection from a ferromagnet (F) into a normal metal (N) Nonequilibrium magnetization (spin accumulation) is injected into N Spin transport across the F/N interface Q.Li@Physics.WHU@2015.3
Spin detection and spin accumulation Z=0: spin-polarized current is detected Z=∞: voltage VS is measured – spin accumulation at N (usually superconductor) Q.Li@Physics.WHU@2015.3
Spin-transfer torque memory Spin-transfer torque can be used to flip the elements STT-MRAM is non-volatile memory with near-zero leakage power consumption Q.Li@Physics.WHU@2015.3