1.8 Functionality of ‘Spin’ in Spintronics
17
Using this spintronics technology, many spintronic devices are making in progress
that stems from combining the advantages of magnetism and semiconductors. Those
devices are supposed to be non-volatile, versatile, fast and capable of storing and
processing data simultaneously. Furthermore, in order to operate, those devices
consume less energy. In this context, it should be mentioned that spintronic devices
are either revolutionizing or having potential to revolutionize high-density data
storage, microelectronics, sensors, quantum computing, bio-medical applications
etc. Some of the spintronic devices are magnetic read head, magnetoresistive random
access memory (MRAM), spin transistor, spin torque oscillators etc.
1.9 Different Branches of Spintronics
Spintronics has been extensively researched worldwide in the last few decades. Even
today it is one of the most attractive and interesting research fields due to its huge
prospect in industrial applications. Extensive research in this field has opened up
new avenues in the implementation of innovative and improved spintronic devices.
Developments have been observed in both the front (i) choice of material and (ii)
method of manipulation of the magnetic state.
1.9.1 Branching Based on Choice of Materials
Spintronics started its journey with ferromagnetic materials and has proved its potential towards realization of spintronic devices. But, nowadays, more versatile materials have drawn widespread attention and have shown spintronic phenomena. The
front runner is antiferromagnetic materials. They are greatly more common and
are allowed in each magnetic symmetry group, in contrast to ferromagnets (FMs).
Antiferromagnets (AFMs) can be insulators, metals, semimetals, semiconductors
or superconductors, whereas FMs are primarily metals. Rigorous research leads to
material based classification of spintronics, like metallic spintronics, semiconductor
spintronics, molecular spintronics etc. (Fig. 1.3).
Metallic spintronics
The simplest approach of producing spin-polarized current is to flow electronic
current through a ferromagnetic material having spontaneous magnetization.
Discovery of giant magnetoresistance (GMR) device is the result of the most direct
application of this effect. Typical GMR device comprises at least two ferromagnetic layers and a non-magnetic metallic spacer layer in between them. During the
parallel alignment of the magnetization vectors of those two ferromagnetic layers,
electrical resistance exhibits low value, which means a higher current yield at constant
voltage. However, during antiparallel orientation of magnetization of the ferromagnetic layers, the electrical resistance will be low pretty high. This constitutes a
17
Using this spintronics technology, many spintronic devices are making in progress
that stems from combining the advantages of magnetism and semiconductors. Those
devices are supposed to be non-volatile, versatile, fast and capable of storing and
processing data simultaneously. Furthermore, in order to operate, those devices
consume less energy. In this context, it should be mentioned that spintronic devices
are either revolutionizing or having potential to revolutionize high-density data
storage, microelectronics, sensors, quantum computing, bio-medical applications
etc. Some of the spintronic devices are magnetic read head, magnetoresistive random
access memory (MRAM), spin transistor, spin torque oscillators etc.
1.9 Different Branches of Spintronics
Spintronics has been extensively researched worldwide in the last few decades. Even
today it is one of the most attractive and interesting research fields due to its huge
prospect in industrial applications. Extensive research in this field has opened up
new avenues in the implementation of innovative and improved spintronic devices.
Developments have been observed in both the front (i) choice of material and (ii)
method of manipulation of the magnetic state.
1.9.1 Branching Based on Choice of Materials
Spintronics started its journey with ferromagnetic materials and has proved its potential towards realization of spintronic devices. But, nowadays, more versatile materials have drawn widespread attention and have shown spintronic phenomena. The
front runner is antiferromagnetic materials. They are greatly more common and
are allowed in each magnetic symmetry group, in contrast to ferromagnets (FMs).
Antiferromagnets (AFMs) can be insulators, metals, semimetals, semiconductors
or superconductors, whereas FMs are primarily metals. Rigorous research leads to
material based classification of spintronics, like metallic spintronics, semiconductor
spintronics, molecular spintronics etc. (Fig. 1.3).
Metallic spintronics
The simplest approach of producing spin-polarized current is to flow electronic
current through a ferromagnetic material having spontaneous magnetization.
Discovery of giant magnetoresistance (GMR) device is the result of the most direct
application of this effect. Typical GMR device comprises at least two ferromagnetic layers and a non-magnetic metallic spacer layer in between them. During the
parallel alignment of the magnetization vectors of those two ferromagnetic layers,
electrical resistance exhibits low value, which means a higher current yield at constant
voltage. However, during antiparallel orientation of magnetization of the ferromagnetic layers, the electrical resistance will be low pretty high. This constitutes a