Sadamichi Maekawa

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The generation of electric voltage by placing a conductor in a temperature gradient is called the Seebeck effect. Its efficiency is represented by the Seebeck coefficient, S, which is defined as the ratio of the generated electric voltage to the temperature difference, and is determined by the scattering rate and the density of the conduction electrons. The(More)
The energy bandgap of an insulator is large enough to prevent electron excitation and electrical conduction. But in addition to charge, an electron also has spin, and the collective motion of spin can propagate-and so transfer a signal-in some insulators. This motion is called a spin wave and is usually excited using magnetic fields. Here we show that a(More)
OBJECTIVE To clarify the pathogenetic significance of the topographic distribution of leptomeningeal glioneuronal heterotopia, a common finding in holoprosencephaly. DESIGN Gross, histological, and immunohistochemical observations of alobar holoprosencephaly in brain specimens taken at autopsy. SETTING Referral center. MATERIALS Brains removed at(More)
Using the spin Hall effect, magnetization relaxation in a Ni_{81}Fe_{19}/Pt film is manipulated electrically. An electric current applied to the Pt layer exerts spin torque on the entire magnetization of the Ni81Fe19 layer via the macroscopic spin transfer induced by the spin Hall effect and modulates the magnetization relaxation in the Ni81Fe19 layer. This(More)
We theoretically study the electron transport through a magnetic point contact (PC) with special attention given to the effect of an atomic scale domain wall (DW). The spin precession of a conduction electron is forbidden in such an atomic scale DW and the sequence of quantized conductances depends on the relative orientation of magnetizations between left(More)
Magnetic domain wall motion induced by magnetic fields and spin-polarized electrical currents is experimentally well established. A full understanding of the underlying mechanisms, however, remains elusive. For the ferromagnetic semiconductor (Ga,Mn)As, we have measured and compared such motions in the thermally activated subthreshold, or "creep," regime,(More)
The electromotive force (e.m.f.) predicted by Faraday's law reflects the forces acting on the charge, -e, of an electron moving through a device or circuit, and is proportional to the time derivative of the magnetic field. This conventional e.m.f. is usually absent for stationary circuits and static magnetic fields. There are also forces that act on the(More)
The control of the magnetism of ultra-thin ferromagnetic layers using an electric field, rather than a current, has many potential technologically important applications. It is usually insisted that such control occurs via an electric field induced surface charge doping that modifies the magnetic anisotropy. However, it remains the case that a number of key(More)
The effect of a gate voltage ͑V g ͒ on the spin splitting of an electronic level in a quantum dot ͑QD͒ attached to ferromagnetic leads is studied in the Kondo regime using a generalized numerical renormalization group technique. We find that the V g dependence of the QD level spin splitting strongly depends on the shape of the density of states ͑DOS͒. For(More)
Magnons are the elementary excitations of a magnetically ordered system. In ferromagnets, only a single band of low-energy magnons needs to be considered, but in ferrimagnets the situation is more complex owing to different magnetic sublattices involved. In this case, low lying optical modes exist that can affect the dynamical response. Here we show that(More)