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Elyasi, M.*; Saito, Eiji; Bauer, G. E. W.*
Physical Review B, 105(5), p.054403_1 - 054403_12, 2022/02
Times Cited Count：7 Percentile：75.56(Materials Science, Multidisciplinary)Kim, S. K.*; Nakata, Koki; Loss, D.*; Tserkovnyak, Y.*
Physical Review Letters, 122(5), p.057204_1 - 057204_6, 2019/02
Times Cited Count：53 Percentile：93.83(Physics, Multidisciplinary)We theoretically study the thermal Hall effect by magnons in skyrmion crystal phases of ferrimagnets in the vicinity of the angular momentum compensation point (CP). For an experimental proposal, we predict that themagnonic thermal Hall conductivity changes its sign when the ferrimagnet is tuned across the CP, providing a way to control heat flux in spin-caloritronic devices on the one hand and a feasible way todetect the CP of ferrimagnets on the other hand.
Nakata, Koki
no journal, ,
Recently, non-Hermitian quantum mechanics has been attracting considerable attention. The key concepts of quantum mechanics are quantum fluctuations. Quantum fluctuations of quantum fields confined in a finite-size system induce the zero-point energy shift. This quantum phenomenon, the Casimir effect, is one of the most striking phenomena of quantum mechanics in the sense that there are no classical analogs and has been drawing much attention from various research areas, including high energy physics, beyond the hierarchy of energy scales. However, the non-Hermitian extension of the Casimir effect and the application to spintronics remain missing ingredients. Here we fill this gap. By developing a magnonic analog of the Casimir effect into non-Hermitian systems, we show that energy dissipation serves as a key ingredient of Casimir engineering to control and manipulate the Casimir effect of magnons.
Nakata, Koki
no journal, ,
Recently, there has been a growing interest in non-Hermitian quantum mechanics. However, the non-Hermitian extension of the Casimir effect and the application to spintronics remain missing ingredients. Here we fill this gap. By developing a magnonic analog of the Casimir effect into non-Hermitian systems, we show that this non-Hermitian Casimir effect of magnons is enhanced as the Gilbert damping constant (i.e., the energy dissipation rate) increases. When the damping constant exceeds a critical value, the non-Hermitian Casimir effect of magnons exhibits an oscillating behavior, including a beating one, as a function of the film thickness and is characterized by the exceptional point. Our result suggests that energy dissipation serves as a key ingredient of Casimir engineering.
Nakata, Koki
no journal, ,
Recently, there has been a growing interest in non-Hermitian quantum mechanics. However, the non-Hermitian extension of the Casimir effect and the application to spintronics remain missing ingredients. Here we fill this gap. By developing a magnonic analog of the Casimir effect into non-Hermitian systems, we show that this non-Hermitian Casimir effect of magnons is enhanced as the Gilbert damping constant (i.e., the energy dissipation rate) increases. When the damping constant exceeds a critical value, the non-Hermitian Casimir effect of magnons exhibits an oscillating behavior, including a beating one, as a function of the film thickness and is characterized by the exceptional point. Our result suggests that energy dissipation serves as a key ingredient of Casimir engineering.
