“ RELATIVISTIC CHIPS: THE SPINTRONICS THEORY ”

1. “RELATIVISTIC CHIPS: THE SPINTRONICS THEORY” PRESENTED BY ASISH PADHY Roll # EC20017129 UNDER THE GUIDANCE OF Mr. BHAWANI PATNAIK Technical Seminar, Advisor

2. TOPICS OF DISCUSSION • The Topics of Discussion are : • 1. Birth of A New Era. • 2. Relativistic Chips: The Concept. • 3. Spintronic Chips: The Technology. • 4. Spintronics Devices. • 5. Limitations. • 6. Conclusion.

3. INTRODUCTION • No microprocessor of the world can challenge BRAIN, the ultimate biochemical machine. • Moore’s law still holds good. • Heat and energy are the two main constraints of the present IC technology. • Relativity may be the Answer. • Even the world’s fastest computers are not very faster, but the electrons in them do.

4. RELATIVISTIC CHIPS:THE CONCEPT • Einstein proposed the THEORY OF RELATIVITY. • THOERY OF RELATIVITY suggests a new design for microchips that relies on the spin of electrons. • These so-called relativistic effects are all minuscule, however, unless the object accelerates to a significant fraction of c, which is about 300 million meters per second. • Though the high end chips are not as fast as light but the electrons inside them do. • Contd…

6. SPINTRONICS, short for spin electronics, is the study of electron spin in materials in order to better understand its behavior, with the hope of developing an entirely new generation of microelectronic devices. SPINTRONICS:THE TECHNOLOGY SPIN Two parts of his personality!!! MR. ELECTRON CHARGE

7. An electron is just like such a spinning sphere of charge. The electron has a quantum property, called spin, that makes it behave almost as if it were a magnet twirling about the axis connecting its north and south poles. Electrons (spheres) can have spins oriented in different directions.

8. A magnetic field causes an electron to swivel like the needle of a compass to line up with the field (left). But the spin axis also precesses like a wobbling top (right). When the magnetic field is removed, the electron stops precessing and locks the orientation of its spin.

9. The Spintronic devices have opened us to a whole new world of high-tech technology. Some of these devices to name are: RELATIVISTIC TRANSISTORS. MRAM (MAGNETIC RANDOM ACCESSS MEMORY). TRANSPINNORS. SPINTRONIC SOLAR CELLS. SPINTRONICS DEVICES

10. SPIN FET was proposed in 1990 by Supriyo Datta and Biswajit A. Das, at Purdue University, in West Lafayette. They proposed a current modulator device based on the electric field modification of spin precession in a narrow gap semiconductor. In this device, the spin-polarized electrons would be injected with the use of a ferromagnetic electrode that forms an ohmic contact with the semiconductor and would be detected with a second ferromagnetic electrode (spin analyzer) contact. RELATIVISTIC TRANSISTORS

13. MRAM stands for Magnetic Random Access Memory. It places the magnetic domains on the surface of a silicon chip and places a magneto-resistive sensor beneath every one of them. Just like a hard disk, the information stored in the magnetic domains is non-volatile. It is not lost when the power goes off. The two main concept that govern MRAM technology are: Giant Magnetoresistance (GMR) effect The Tunneling Magneto-Resistive (TMR) effect Contd… MRAM (Magnetic RAM)

14. GAINT MAGNETORESISTANCE TUNNELING MAGNETO- EFFECT RESISTIVE EFFECT

15. OPERATION To write to the memory cell, a current pulse in the bit line generates a localized magnetic field that sets the ‘free’ magnetic layer into the appropriate orientation for a 0 or a 1, while the other magnetic layer is held with a fixed orientation. To read the memory cell, a current is passed through it via the selection transistor to measure its resistance.

16. A Transpinnor is a bridge of four electrically connected GMR(giant magnetoresistive) films whose resistance is controlled by the magnetic field from the current in one or more input striplines electrically isolated from the GMR films. Transpinnors can be used as selection-matrix elements for magnetic memories, for logic elements of all kinds (e.g., AND, OR, XOR, NAND, NOT), for amplifiers, differential amplifiers. TRANSPINNORS

17. Based on principle of the spin-polarized P-N junction SPINTRONIC SOLAR CELLS

18. Every technology comes with its own short comings. Much remains to be understood about the behavior of electron spins in materials for technological applications. HAZARDS OF HOLES. Fundamental challenges of creating and measuring spin, understanding better the transport of spin at interfaces. Scope of the present IC fabrication technology. LIMITATIONS

19. A number of spin-based microelectronic devices have been proposed, and the giant magneto-resistive sandwich structure is a proven commercial success, being a part of every computer coming off the production line. Spintronic-based nonvolatile memory elements may very well become available in the near future. Limitations had always made MAN to go beyond the horizon. Somebody had very rightly said “Limitations are not there to tip you Off but only for Boosting You Up” CONCLUSION

20. QUESTIONS ?

21.  THANK YOU 