7.9 Antiferromagnetic Opto-spintronics
177
drawn much more attention in recent time due to its intriguing features compared to
ferromagnets: they.
• are robust against perturbation,
• produce no stray fields,
• exhibit ultrafast dynamics.
• generate large magneto-transport effects.
7.9.1 Brief History of the Emergence of Antiferromagnetic
Spintronics
Antiferromagnetic spintronics has been formally emerged inspired by the discovery
of a spin-valve-like magneto-resistance of an antiferromagnet based tunnel junction
in 2011. Extensive researches have been carried out to study the roles of antiferromagnets in spintronics devices. In 2013, the room temperature tunnelling anisotropic
magnetoresistances have been realized in antiferromagnetic material. The emergence
of a room temperature antiferromagnetic memory resistor is witnessed in 2014. The
reversible electrical switching in antiferromagnets is observed in 2016. Of late, many
fascinating phenomena like large anomalous Hall effect, spin Hall magnetoresistance
and skyrmions have been noticed with antiferromagnets. They have accelerated the
research for the development of antiferromagnetic spintronics. Field-free switching
of magnetization in antiferromagnets through spin–orbit torque has also been realized. Therefore, it becomes very important to know the physics and engineering for
skilful control of magnetic states of antiferromagnets. Efficient controlling of magnetization can be done through magnetic, electrical, optical and strain manipulation.
Here we will discuss about optical manipulation only.
7.9.2 Probing and Optical Manipulation of Antiferromagnets
In antiferromagnetic materials, the elementary magnetic moments are spontaneously
long-range ordered. However, the net magnetic moment is zero or small compared
to the sum of the magnitudes of the participating magnetic moments. In compared to
ferromagnetism, there are different numbers of arrangement of magnetic moments
on a lattice to give net moment zero (Kimel et al. 2004; Nˇ emec et al. 2018; Feng et al.
2015; Saidl et al. 2017; Nishitani et al. 2012; Manz et al. 2016; Radu et al. 2010).
All nearest-neighbour magnetic atoms are collinear and aligned antiferromagnetically in perovskite LaFeO 3 . Alternatively aligned ferromagnetic planes are present
in LaMnO 3 . In YMnO 3 , three magnetic sublattices are rotated by 120°. Helical order
is found in rare-earth metals and multiferroics like TbMnO 3 . Electromagnetic radiation faces a strong challenge towards reorientation of spins in antiferromagnets. The
required field strength may be of the order of tens or hundreds of Tesla. Fortunately,
177
drawn much more attention in recent time due to its intriguing features compared to
ferromagnets: they.
• are robust against perturbation,
• produce no stray fields,
• exhibit ultrafast dynamics.
• generate large magneto-transport effects.
7.9.1 Brief History of the Emergence of Antiferromagnetic
Spintronics
Antiferromagnetic spintronics has been formally emerged inspired by the discovery
of a spin-valve-like magneto-resistance of an antiferromagnet based tunnel junction
in 2011. Extensive researches have been carried out to study the roles of antiferromagnets in spintronics devices. In 2013, the room temperature tunnelling anisotropic
magnetoresistances have been realized in antiferromagnetic material. The emergence
of a room temperature antiferromagnetic memory resistor is witnessed in 2014. The
reversible electrical switching in antiferromagnets is observed in 2016. Of late, many
fascinating phenomena like large anomalous Hall effect, spin Hall magnetoresistance
and skyrmions have been noticed with antiferromagnets. They have accelerated the
research for the development of antiferromagnetic spintronics. Field-free switching
of magnetization in antiferromagnets through spin–orbit torque has also been realized. Therefore, it becomes very important to know the physics and engineering for
skilful control of magnetic states of antiferromagnets. Efficient controlling of magnetization can be done through magnetic, electrical, optical and strain manipulation.
Here we will discuss about optical manipulation only.
7.9.2 Probing and Optical Manipulation of Antiferromagnets
In antiferromagnetic materials, the elementary magnetic moments are spontaneously
long-range ordered. However, the net magnetic moment is zero or small compared
to the sum of the magnitudes of the participating magnetic moments. In compared to
ferromagnetism, there are different numbers of arrangement of magnetic moments
on a lattice to give net moment zero (Kimel et al. 2004; Nˇ emec et al. 2018; Feng et al.
2015; Saidl et al. 2017; Nishitani et al. 2012; Manz et al. 2016; Radu et al. 2010).
All nearest-neighbour magnetic atoms are collinear and aligned antiferromagnetically in perovskite LaFeO 3 . Alternatively aligned ferromagnetic planes are present
in LaMnO 3 . In YMnO 3 , three magnetic sublattices are rotated by 120°. Helical order
is found in rare-earth metals and multiferroics like TbMnO 3 . Electromagnetic radiation faces a strong challenge towards reorientation of spins in antiferromagnets. The
required field strength may be of the order of tens or hundreds of Tesla. Fortunately,