2.12 Field- and Heat-Driven Spintronics Effect
63
strip in the presence of an applied magnetic field by Edwin H. Hall. Significantly, the
Hall effect made it feasible for a direct measurement of the carrier density. Moreover,
it enables a relatively simple measurement of electrical resistivity and the mobility of
carriers in semiconductor. Owing to simple measurement technique, cheap and fast
reversal time, the Hall effect becomes an inevitable technique in the semiconductor
industry.
The spin Hall effect (SHE) originates from the coupling of the charge and spin
currents mediated by the spin–orbit coupling. In an original work, Russian physicists,
Mikhail I. Dyakonov and Vladimir I. Perel, have predicted this effect in 1971. In order
to predict the extrinsic SHE, they referred to the phenomena of Mott scattering (1929)
and of the anomalous Hall effect (AHE) (1881). The main points, identified by them,
are as follows:
1. Due to Mott scattering, spin-dependent asymmetric deflection of electron beams
has been observed in vacuum.
2. Mott’s skew scattering has been considered as one of the origins of the AHE,
experienced by conduction electrons in ferromagnets.
They have proposed a technique to measure inverse spin Hall effect (ISHE) under
optical spin orientations in semiconductors. The name ‘spin Hall effect’ has been
first suggested by Hirsch in 1999.
What is Hall effect?
Hall effect is a very familiar effect, proposed by Edwin Hall. This is basically related
to creation of potential difference across an electrical conductor under the application
of a magnetic field. The magnetic field should be applied in a direction perpendicular
to the flow of electrical current. In this case, accumulation of opposite charges take
place due to the action of Lorentz force, mediated by the magnetic field, at the
sample boundary. Hall effect plays a very significant role in physics. It provides us a
means for effective measurement of the carrier density, magnetic field and the type
of semiconductor.
What is spin Hall effect (SHE)?
An intriguing phenomenon of spin accumulation to opposite edges of a given sample,
which may be magnetic material or not, is called spin Hall effect (SHE). Such effect
results in an entirely non-magnetic material to become magnetic, when an electrical
current flows through it. However, this effect also plays an important role in a ferromagnetic material as well. Therefore, it comes out that SHE is the feature of both
non-magnetic and magnetic metal. SHE does not accompany with Hall voltage.
Instead, opposite signs of spin polarization may appear at the edges of the sample,
even if no magnetic field is applied externally. Such feature is generic to both extrinsic
and intrinsic SHE. At the onset, we may mention that the concept of SHE has been
adopted from the extrinsic anomalous Hall effect (AHE). Noteworthy, AHE appears
due to-spin dependent scattering process. Accordingly, we understand that in case of
SHE, the up-and down-spin electrons are scattered by spin–orbit scattering itself or
63
strip in the presence of an applied magnetic field by Edwin H. Hall. Significantly, the
Hall effect made it feasible for a direct measurement of the carrier density. Moreover,
it enables a relatively simple measurement of electrical resistivity and the mobility of
carriers in semiconductor. Owing to simple measurement technique, cheap and fast
reversal time, the Hall effect becomes an inevitable technique in the semiconductor
industry.
The spin Hall effect (SHE) originates from the coupling of the charge and spin
currents mediated by the spin–orbit coupling. In an original work, Russian physicists,
Mikhail I. Dyakonov and Vladimir I. Perel, have predicted this effect in 1971. In order
to predict the extrinsic SHE, they referred to the phenomena of Mott scattering (1929)
and of the anomalous Hall effect (AHE) (1881). The main points, identified by them,
are as follows:
1. Due to Mott scattering, spin-dependent asymmetric deflection of electron beams
has been observed in vacuum.
2. Mott’s skew scattering has been considered as one of the origins of the AHE,
experienced by conduction electrons in ferromagnets.
They have proposed a technique to measure inverse spin Hall effect (ISHE) under
optical spin orientations in semiconductors. The name ‘spin Hall effect’ has been
first suggested by Hirsch in 1999.
What is Hall effect?
Hall effect is a very familiar effect, proposed by Edwin Hall. This is basically related
to creation of potential difference across an electrical conductor under the application
of a magnetic field. The magnetic field should be applied in a direction perpendicular
to the flow of electrical current. In this case, accumulation of opposite charges take
place due to the action of Lorentz force, mediated by the magnetic field, at the
sample boundary. Hall effect plays a very significant role in physics. It provides us a
means for effective measurement of the carrier density, magnetic field and the type
of semiconductor.
What is spin Hall effect (SHE)?
An intriguing phenomenon of spin accumulation to opposite edges of a given sample,
which may be magnetic material or not, is called spin Hall effect (SHE). Such effect
results in an entirely non-magnetic material to become magnetic, when an electrical
current flows through it. However, this effect also plays an important role in a ferromagnetic material as well. Therefore, it comes out that SHE is the feature of both
non-magnetic and magnetic metal. SHE does not accompany with Hall voltage.
Instead, opposite signs of spin polarization may appear at the edges of the sample,
even if no magnetic field is applied externally. Such feature is generic to both extrinsic
and intrinsic SHE. At the onset, we may mention that the concept of SHE has been
adopted from the extrinsic anomalous Hall effect (AHE). Noteworthy, AHE appears
due to-spin dependent scattering process. Accordingly, we understand that in case of
SHE, the up-and down-spin electrons are scattered by spin–orbit scattering itself or