40,333 research outputs found
Effect of spin relaxations on the spin mixing conductances for a bilayer structure
The spin current can result in a spin-transfer torque in the
normal-metal(NM)|ferromagnetic-insulator(FMI) or
normal-metal(NM)|ferromagnetic-metal(FMM) bilayer. In the earlier study on this
issue, the spin relaxations were ignored or introduced phenomenologically. In
this paper, considering the FMM or FMI with spin relaxations described by a
non-Hermitian Hamiltonian, we derive an effective spin-transfer torque and an
effective spin mixing conductance in the non-Hermitian bilayer. The dependence
of the effective spin mixing conductance on the system parameters (such as
insulating gap, \textit{s-d} coupling, and layer thickness) as well as the
relations between the real part and the imaginary part of the effective spin
mixing conductance are given and discussed. We find that the effective spin
mixing conductance can be enhanced in the non-Hermitian system. This provides
us with the possibility to enhance the spin mixing conductance
Engineering the accurate distortion of an object's temperature-distribution signature
It is up to now a challenge to control the conduction of heat. Here we
develop a method to distort the temperature distribution signature of an object
at will. As a result, the object accurately exhibits the same temperature
distribution signature as another object that is predetermined, but actually
does not exist in the system. Our finite element simulations confirm the
desired effect for different objects with various geometries and compositions.
The underlying mechanism lies in the effects of thermal metamaterials designed
by using this method. Our work is of value for applications in thermal
engineering.Comment: 11 pages, 4 figure
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