Chapter 7
Spin Torque and Zeta Force in Allene-Type
Molecules
Masahiro Fukuda, Masato Senami, and Akitomo Tachibana
Abstract The spin torque, the zeta force, and the zeta potential, which are significant quantities to describe the local picture of spin dynamics, are studied by using
allene-type molecules (C 3 H 4 and C 3 H 2 Li 2 ) in their stationary states. We show that
the two molecules have different distribution patterns of these quantities though
their structures are very similar to each other. It is also shown that the zeta potential
distribution is almost independent of the electron density distribution.
7.1 Introduction
Due to the great innovation of the field of spintronics, the electron spin is now one
of the most interesting quantities for electronic devices. The control of the spin is
the key element of the spintronics. Hence, the further knowledge of the nature of
the electron spin enables us to improve spintronics devices. The size of spintronics
materials is already about nano-scale. For these microscopic materials, local effects
are relatively important for the evolution of the electron spin. However, few studies
for the local evolution of the electron spin are reported in spite of its necessity. We
consider that it is important to analyze the local evolution from the first principles
calculation.
In our laboratory, nano-materials have been studied by using several local quantities proposed by one of the authors [1–4]. For example, the local dielectric constant
and local polarizability clarify the local dielectric response in high dielectric constant thin films. We have reported the local dielectric property of hafnium dioxide,
which is a candidate for materials of a future semiconductor [5–10]. For the study
of the local electric conductive property, the local conductivity is used to investigate the conductive property of nanowire materials [11–14]. For the description of
local torque for the electron spin, the local spin torque and the zeta force have been
proposed based on quantum field theory [1–4] and we have studied these quantities
for atoms of transition elements and dimers of alkali metal atoms [15, 16]. In these
A. Tachibana (B)
Department of Micro-Engineering, Kyoto University, Kyoto 615-8540, Japan
e-mail: akitomo@scl.kyoto-u.ac.jp
M. Hotokka et al. (eds.), Advances in Quantum Methods and Applications in
Chemistry, Physics, and Biology, Progress in Theoretical Chemistry and Physics 27,
DOI 10.1007/978-3-319-01529-3_7,
© Springer International Publishing Switzerland 2013
131
Spin Torque and Zeta Force in Allene-Type
Molecules
Masahiro Fukuda, Masato Senami, and Akitomo Tachibana
Abstract The spin torque, the zeta force, and the zeta potential, which are significant quantities to describe the local picture of spin dynamics, are studied by using
allene-type molecules (C 3 H 4 and C 3 H 2 Li 2 ) in their stationary states. We show that
the two molecules have different distribution patterns of these quantities though
their structures are very similar to each other. It is also shown that the zeta potential
distribution is almost independent of the electron density distribution.
7.1 Introduction
Due to the great innovation of the field of spintronics, the electron spin is now one
of the most interesting quantities for electronic devices. The control of the spin is
the key element of the spintronics. Hence, the further knowledge of the nature of
the electron spin enables us to improve spintronics devices. The size of spintronics
materials is already about nano-scale. For these microscopic materials, local effects
are relatively important for the evolution of the electron spin. However, few studies
for the local evolution of the electron spin are reported in spite of its necessity. We
consider that it is important to analyze the local evolution from the first principles
calculation.
In our laboratory, nano-materials have been studied by using several local quantities proposed by one of the authors [1–4]. For example, the local dielectric constant
and local polarizability clarify the local dielectric response in high dielectric constant thin films. We have reported the local dielectric property of hafnium dioxide,
which is a candidate for materials of a future semiconductor [5–10]. For the study
of the local electric conductive property, the local conductivity is used to investigate the conductive property of nanowire materials [11–14]. For the description of
local torque for the electron spin, the local spin torque and the zeta force have been
proposed based on quantum field theory [1–4] and we have studied these quantities
for atoms of transition elements and dimers of alkali metal atoms [15, 16]. In these
A. Tachibana (B)
Department of Micro-Engineering, Kyoto University, Kyoto 615-8540, Japan
e-mail: akitomo@scl.kyoto-u.ac.jp
M. Hotokka et al. (eds.), Advances in Quantum Methods and Applications in
Chemistry, Physics, and Biology, Progress in Theoretical Chemistry and Physics 27,
DOI 10.1007/978-3-319-01529-3_7,
© Springer International Publishing Switzerland 2013
131