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Ken-ichi Uchida - One of the best experts on this subject based on the ideXlab platform.
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enhancement of charge to spin current conversion in a ni pt bilayer film detected by spin Peltier Effect
Japanese Journal of Applied Physics, 2020Co-Authors: Takumi Yamazaki, Ryo Iguchi, Ken-ichi Uchida, Hosei NaganoAbstract:We demonstrate the enhancement of charge-to-spin current conversion by a ferromagnet/paramagnet interface. The enhancement is confirmed by comparing the spin Peltier Effect (SPE) between Ni/Pt/yttrium-iron-garnet (YIG) and Pt/YIG hybrid structures, where the SPE signal is proportional to the spin current generated in the Ni/Pt or Pt layer. The SPE signal normalized by charge current density for the Ni/Pt/YIG system increases by 65% compared to the Pt/YIG system, which cannot be explained by other thermoelectric and thermo-spin Effects. This result suggests the presence of additive charge-to-spin current conversion at the Ni/Pt interface, providing simple ways to improve spin-injection efficiency.
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transient response of the spin Peltier Effect revealed by lock in thermoreflectance measurements
Physical Review B, 2020Co-Authors: Takumi Yamazaki, Ryo Iguchi, T Ohkubo, Hosei Nagano, Ken-ichi UchidaAbstract:The transient response and length scale of the spin Peltier Effect (SPE) -- heat-current generation due to magnon spin currents -- are revealed by frequency-domain lock-in thermoreflectance. The amplitude of the SPE-induced temperature modulation decreases when the excitation frequency exceeds 1 kHz. The frequency dependence is determined by the characteristic length of the SPE, which is estimated to be 0.94 \textmu{}m for yttrium iron garnet. This length is similar to, but smaller than, the length scale of the spin Seebeck Effect, suggesting that the electrically excited magnons in SPE are of a different nature when compared with the thermally excited magnons in the spin Seebeck Effect.
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transient response of spin Peltier Effect revealed by lock in thermoreflectance measurement
arXiv: Materials Science, 2019Co-Authors: Takumi Yamazaki, Ryo Iguchi, T Ohkubo, Hosei Nagano, Ken-ichi UchidaAbstract:Transient response of the spin Peltier Effect (SPE) in a Pt/yttrium iron garnet junction system has been investigated by means of a lock-in thermoreflectance method. We applied an alternating charge current to the Pt layer to drive SPE through the spin Hall Effect, and measured the AC response of the resultant SPE-induced temperature modulation at frequencies ranging from 10 Hz to 1 MHz. We found that the SPE-induced temperature modulation decreases with increasing the frequency when the frequency is >1 kHz. This is a characteristic feature of SPE revealed by the high frequency measurements based on the lock-in thermoreflectance, while previous low frequency measurements showed that the SPE signal is independent of the frequency. We attribute the decrease of the temperature modulation to the length scale of the SPE-induced heat current; by comparing the experimental results with one-dimensional heat conduction calculations, the length scale of SPE is estimated to be 0.94 {\mu}m.
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direct observation of magneto Peltier Effect in current in plane giant magnetoresistive spin valve
Applied Physics Letters, 2019Co-Authors: Hiroyasu Nakayama, Ryo Iguchi, T M Nakatani, Takeshi Seki, Ken-ichi UchidaAbstract:We report on the direct observation of the magneto-Peltier Effect in a current-in-plane giant magnetoresistive (CIP-GMR) spin valve. By means of the recently developed thermoelectric imaging technique based on lock-in thermography, we demonstrate that thermoelectric cooling and heating are generated by applying a local magnetic field to the CIP-GMR spin-valve film, confirming the different Peltier coefficients of the spin valve between the parallel and antiparallel magnetization configurations. The cooling and heating positions are found to be tuned simply by changing the magnitude of the local magnetic field. This versatile and reconfigurable thermoelectric conversion functionality may provide a thermal management method for CIP-GMR magnetic sensors.We report on the direct observation of the magneto-Peltier Effect in a current-in-plane giant magnetoresistive (CIP-GMR) spin valve. By means of the recently developed thermoelectric imaging technique based on lock-in thermography, we demonstrate that thermoelectric cooling and heating are generated by applying a local magnetic field to the CIP-GMR spin-valve film, confirming the different Peltier coefficients of the spin valve between the parallel and antiparallel magnetization configurations. The cooling and heating positions are found to be tuned simply by changing the magnitude of the local magnetic field. This versatile and reconfigurable thermoelectric conversion functionality may provide a thermal management method for CIP-GMR magnetic sensors.
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thickness dependence of spin Peltier Effect visualized by thermal imaging technique
arXiv: Materials Science, 2019Co-Authors: Shunsuke Daimo, Ken-ichi Uchida, Naomi Ujiie, Yasuyuki Hattori, Rei Tsuboi, Eiji SaitohAbstract:Magnon propagation length in a ferrimagnetic insulator yttrium iron garnet (YIG) has been investigated by measuring and analyzing the YIG-thickness t_YIG dependence of the spin Peltier Effect (SPE) in a Pt/YIG junction system. By means of the lock-in thermography technique, we measured the spatial distribution of the SPE-induced temperature modulation in the Pt/YIG system with the t_YIG gradation, allowing us to obtain the accurate t_YIG dependence of SPE with high t_YIG resolution. Based on the t_YIG dependence of SPE, we verified the applicability of several phenomenological models to estimate the magnon diffusion length in YIG.
Ryo Iguchi - One of the best experts on this subject based on the ideXlab platform.
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enhancement of charge to spin current conversion in a ni pt bilayer film detected by spin Peltier Effect
Japanese Journal of Applied Physics, 2020Co-Authors: Takumi Yamazaki, Ryo Iguchi, Ken-ichi Uchida, Hosei NaganoAbstract:We demonstrate the enhancement of charge-to-spin current conversion by a ferromagnet/paramagnet interface. The enhancement is confirmed by comparing the spin Peltier Effect (SPE) between Ni/Pt/yttrium-iron-garnet (YIG) and Pt/YIG hybrid structures, where the SPE signal is proportional to the spin current generated in the Ni/Pt or Pt layer. The SPE signal normalized by charge current density for the Ni/Pt/YIG system increases by 65% compared to the Pt/YIG system, which cannot be explained by other thermoelectric and thermo-spin Effects. This result suggests the presence of additive charge-to-spin current conversion at the Ni/Pt interface, providing simple ways to improve spin-injection efficiency.
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transient response of the spin Peltier Effect revealed by lock in thermoreflectance measurements
Physical Review B, 2020Co-Authors: Takumi Yamazaki, Ryo Iguchi, T Ohkubo, Hosei Nagano, Ken-ichi UchidaAbstract:The transient response and length scale of the spin Peltier Effect (SPE) -- heat-current generation due to magnon spin currents -- are revealed by frequency-domain lock-in thermoreflectance. The amplitude of the SPE-induced temperature modulation decreases when the excitation frequency exceeds 1 kHz. The frequency dependence is determined by the characteristic length of the SPE, which is estimated to be 0.94 \textmu{}m for yttrium iron garnet. This length is similar to, but smaller than, the length scale of the spin Seebeck Effect, suggesting that the electrically excited magnons in SPE are of a different nature when compared with the thermally excited magnons in the spin Seebeck Effect.
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transient response of spin Peltier Effect revealed by lock in thermoreflectance measurement
arXiv: Materials Science, 2019Co-Authors: Takumi Yamazaki, Ryo Iguchi, T Ohkubo, Hosei Nagano, Ken-ichi UchidaAbstract:Transient response of the spin Peltier Effect (SPE) in a Pt/yttrium iron garnet junction system has been investigated by means of a lock-in thermoreflectance method. We applied an alternating charge current to the Pt layer to drive SPE through the spin Hall Effect, and measured the AC response of the resultant SPE-induced temperature modulation at frequencies ranging from 10 Hz to 1 MHz. We found that the SPE-induced temperature modulation decreases with increasing the frequency when the frequency is >1 kHz. This is a characteristic feature of SPE revealed by the high frequency measurements based on the lock-in thermoreflectance, while previous low frequency measurements showed that the SPE signal is independent of the frequency. We attribute the decrease of the temperature modulation to the length scale of the SPE-induced heat current; by comparing the experimental results with one-dimensional heat conduction calculations, the length scale of SPE is estimated to be 0.94 {\mu}m.
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direct observation of magneto Peltier Effect in current in plane giant magnetoresistive spin valve
Applied Physics Letters, 2019Co-Authors: Hiroyasu Nakayama, Ryo Iguchi, T M Nakatani, Takeshi Seki, Ken-ichi UchidaAbstract:We report on the direct observation of the magneto-Peltier Effect in a current-in-plane giant magnetoresistive (CIP-GMR) spin valve. By means of the recently developed thermoelectric imaging technique based on lock-in thermography, we demonstrate that thermoelectric cooling and heating are generated by applying a local magnetic field to the CIP-GMR spin-valve film, confirming the different Peltier coefficients of the spin valve between the parallel and antiparallel magnetization configurations. The cooling and heating positions are found to be tuned simply by changing the magnitude of the local magnetic field. This versatile and reconfigurable thermoelectric conversion functionality may provide a thermal management method for CIP-GMR magnetic sensors.We report on the direct observation of the magneto-Peltier Effect in a current-in-plane giant magnetoresistive (CIP-GMR) spin valve. By means of the recently developed thermoelectric imaging technique based on lock-in thermography, we demonstrate that thermoelectric cooling and heating are generated by applying a local magnetic field to the CIP-GMR spin-valve film, confirming the different Peltier coefficients of the spin valve between the parallel and antiparallel magnetization configurations. The cooling and heating positions are found to be tuned simply by changing the magnitude of the local magnetic field. This versatile and reconfigurable thermoelectric conversion functionality may provide a thermal management method for CIP-GMR magnetic sensors.
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systematic investigation of anisotropic magneto Peltier Effect and anomalous ettingshausen Effect in ni thin films
Physical review applied, 2019Co-Authors: Raja Das, Ryo Iguchi, Ken-ichi UchidaAbstract:The anisotropic magneto-Peltier Effect (AMPE) and anomalous Ettingshausen Effect (AEE) have been investigated in U-shaped Ni thin films of varying thickness and substrate by means of the lock-in thermography (LIT) method. We have established a procedure to extract pure AMPE and AEE contributions, separated from other thermoelectric Effects, for ferromagnetic thin films. The measurements of the magnetic-field-angle $\theta_{\rm H}$ dependence of the LIT images clearly show that the temperature modulation induced by the AMPE (AEE) in the Ni films varies with the $\cos 2\theta_{\rm H}$ ($\cos \theta_{\rm H}$) pattern, confirming the symmetry of the AMPE (AEE). The systematic LIT measurements using various substrates show that the AMPE-induced temperature modulation decreases with the increase in thermal conductivity of the substrates, whereas the AEE-induced temperature modulation is almost independent of the thermal conductivity, indicating that the heat loss into the substrates plays an important role in determining the magnitude of the AMPE-induced temperature modulation in thin films. Our experimental results were reproduced by numerical calculations based on a two-dimensional finite element method. These findings provide a platform for investigating the AMPE and AEE in thin film devices.
Eiji Saitoh - One of the best experts on this subject based on the ideXlab platform.
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magnon polarons in the spin Peltier Effect
Physical Review B, 2020Co-Authors: Reimei Yahiro, Shunsuke Daimo, Tomosato Hioki, Takashi Kikkawa, R Ramos, Koichi Oyanagi, Eiji SaitohAbstract:We report the observation of anomalous peak structures induced by hybridized magnon-phonon excitation (magnon polarons) in the magnetic field dependence of the spin Peltier Effect (SPE) in a Lu$_{2}$Bi$_{1}$Fe$_{4}$Ga$_{1}$O$_{12}$ (BiGa:LuIG) with Pt contact. The SPE peaks coincide with magnetic fields tuned to the threshold of magnon-polaron formation, consistent with the previous observation in the spin Seebeck Effect. The enhancement of SPE is attributed to the lifetime increase in spin current caused by magnon-phonon hybridization in BiGa:LuIG.
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thickness dependence of spin Peltier Effect visualized by thermal imaging technique
arXiv: Materials Science, 2019Co-Authors: Shunsuke Daimo, Ken-ichi Uchida, Naomi Ujiie, Yasuyuki Hattori, Rei Tsuboi, Eiji SaitohAbstract:Magnon propagation length in a ferrimagnetic insulator yttrium iron garnet (YIG) has been investigated by measuring and analyzing the YIG-thickness t_YIG dependence of the spin Peltier Effect (SPE) in a Pt/YIG junction system. By means of the lock-in thermography technique, we measured the spatial distribution of the SPE-induced temperature modulation in the Pt/YIG system with the t_YIG gradation, allowing us to obtain the accurate t_YIG dependence of SPE with high t_YIG resolution. Based on the t_YIG dependence of SPE, we verified the applicability of several phenomenological models to estimate the magnon diffusion length in YIG.
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Combinatorial investigation of spin-orbit materials using spin Peltier Effect
Scientific Reports, 2018Co-Authors: Ken-ichi Uchida, Yuya Sakuraba, Shunsuke Daimon, Ryo Iguchi, Michiko Sasaki, Eiji Saitoh, Masahiro GotoAbstract:Conversion between spin and charge currents is essential in spintronics, since it enables spin-orbit-torque magnetization switching, spin-current-driven thermoelectric generation, and nano-scale thermal energy control. To realize efficient spin-charge conversion, a variety of mechanisms, including spin Hall Effects, Rashba-Edelstein Effects, and spin-momentum locking in topological insulators, have been investigated and more comprehensive material exploration is necessary. Here we demonstrate high-throughput screening of spin-charge conversion materials by means of the spin Peltier Effect (SPE). This is enabled by combining recently-developed SPE-imaging techniques with combinatorial materials science; using a composition-spread alloy film formed on a magnetic insulator, we observe the SPE-induced temperature change due to the spin Hall Effect and obtain a continuous mapping of its composition dependence from the single sample. The distribution of the SPE signals reflects local spin-charge conversion capability in the alloy owing to unique heat-generation nature of the SPE. This combinatorial approach will accelerate materials research towards high-performance spintronic devices.
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publisher correction observation of anisotropic magneto Peltier Effect in nickel
Nature, 2018Co-Authors: Ken-ichi Uchida, Ryo Iguchi, Shunsuke Daimo, Eiji SaitohAbstract:In this Letter, owing to an error during the production process, ‘θ H ’ was incorrectly written as ‘θΗH’ six times in the paragraph starting “Up to now,…”. These errors have been corrected online.
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observation of anisotropic magneto Peltier Effect in nickel
Nature, 2018Co-Authors: Ken-ichi Uchida, Ryo Iguchi, Shunsuke Daimo, Eiji SaitohAbstract:The Peltier Effect, discovered in 1834, converts a charge current into a heat current in a conductor, and its performance is described by the Peltier coefficient, which is defined as the ratio of the generated heat current to the applied charge current1,2. To exploit the Peltier Effect for thermoelectric cooling or heating, junctions of two conductors with different Peltier coefficients have been believed to be indispensable. Here we challenge this conventional wisdom by demonstrating Peltier cooling and heating in a single material without junctions. This is realized through an anisotropic magneto-Peltier Effect in which the Peltier coefficient depends on the angle between the directions of a charge current and magnetization in a ferromagnet. By using active thermography techniques3–10, we observe the temperature change induced by this Effect in a plain nickel slab. We find that the thermoelectric properties of the ferromagnet can be redesigned simply by changing the configurations of the charge current and magnetization, for instance, by shaping the ferromagnet so that the current must flow around a curve. Our experimental results demonstrate the suitability of nickel for the anisotropic magneto-Peltier Effect and the importance of spin–orbit interaction in its mechanism. The anisotropic magneto-Peltier Effect observed here is the missing thermoelectric phenomenon in ferromagnetic materials—the Onsager reciprocal of the anisotropic magneto-Seebeck Effect previously observed in ferromagnets—and its simplicity might prove useful in developing thermal management technologies for electronic and spintronic devices. A ‘magneto-Peltier Effect’ produces cooling or heating in a material without junctions, by forcing a change in angle between the current and magnetization in a single ferromagnetic nickel slab.
Shunsuke Daimo - One of the best experts on this subject based on the ideXlab platform.
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magnon polarons in the spin Peltier Effect
Physical Review B, 2020Co-Authors: Reimei Yahiro, Shunsuke Daimo, Tomosato Hioki, Takashi Kikkawa, R Ramos, Koichi Oyanagi, Eiji SaitohAbstract:We report the observation of anomalous peak structures induced by hybridized magnon-phonon excitation (magnon polarons) in the magnetic field dependence of the spin Peltier Effect (SPE) in a Lu$_{2}$Bi$_{1}$Fe$_{4}$Ga$_{1}$O$_{12}$ (BiGa:LuIG) with Pt contact. The SPE peaks coincide with magnetic fields tuned to the threshold of magnon-polaron formation, consistent with the previous observation in the spin Seebeck Effect. The enhancement of SPE is attributed to the lifetime increase in spin current caused by magnon-phonon hybridization in BiGa:LuIG.
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thickness dependence of spin Peltier Effect visualized by thermal imaging technique
arXiv: Materials Science, 2019Co-Authors: Shunsuke Daimo, Ken-ichi Uchida, Naomi Ujiie, Yasuyuki Hattori, Rei Tsuboi, Eiji SaitohAbstract:Magnon propagation length in a ferrimagnetic insulator yttrium iron garnet (YIG) has been investigated by measuring and analyzing the YIG-thickness t_YIG dependence of the spin Peltier Effect (SPE) in a Pt/YIG junction system. By means of the lock-in thermography technique, we measured the spatial distribution of the SPE-induced temperature modulation in the Pt/YIG system with the t_YIG gradation, allowing us to obtain the accurate t_YIG dependence of SPE with high t_YIG resolution. Based on the t_YIG dependence of SPE, we verified the applicability of several phenomenological models to estimate the magnon diffusion length in YIG.
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publisher correction observation of anisotropic magneto Peltier Effect in nickel
Nature, 2018Co-Authors: Ken-ichi Uchida, Ryo Iguchi, Shunsuke Daimo, Eiji SaitohAbstract:In this Letter, owing to an error during the production process, ‘θ H ’ was incorrectly written as ‘θΗH’ six times in the paragraph starting “Up to now,…”. These errors have been corrected online.
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observation of anisotropic magneto Peltier Effect in nickel
Nature, 2018Co-Authors: Ken-ichi Uchida, Ryo Iguchi, Shunsuke Daimo, Eiji SaitohAbstract:The Peltier Effect, discovered in 1834, converts a charge current into a heat current in a conductor, and its performance is described by the Peltier coefficient, which is defined as the ratio of the generated heat current to the applied charge current1,2. To exploit the Peltier Effect for thermoelectric cooling or heating, junctions of two conductors with different Peltier coefficients have been believed to be indispensable. Here we challenge this conventional wisdom by demonstrating Peltier cooling and heating in a single material without junctions. This is realized through an anisotropic magneto-Peltier Effect in which the Peltier coefficient depends on the angle between the directions of a charge current and magnetization in a ferromagnet. By using active thermography techniques3–10, we observe the temperature change induced by this Effect in a plain nickel slab. We find that the thermoelectric properties of the ferromagnet can be redesigned simply by changing the configurations of the charge current and magnetization, for instance, by shaping the ferromagnet so that the current must flow around a curve. Our experimental results demonstrate the suitability of nickel for the anisotropic magneto-Peltier Effect and the importance of spin–orbit interaction in its mechanism. The anisotropic magneto-Peltier Effect observed here is the missing thermoelectric phenomenon in ferromagnetic materials—the Onsager reciprocal of the anisotropic magneto-Seebeck Effect previously observed in ferromagnets—and its simplicity might prove useful in developing thermal management technologies for electronic and spintronic devices. A ‘magneto-Peltier Effect’ produces cooling or heating in a material without junctions, by forcing a change in angle between the current and magnetization in a single ferromagnetic nickel slab.
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lock in thermography measurements of the spin Peltier Effect in a compensated ferrimagnet and its comparison to the spin seebeck Effect
Journal of Physics D, 2018Co-Authors: Ryo Iguchi, Ken-ichi Uchida, Eiji Saitoh, Shunsuke Daimo, A Yagmu, Stepha Geprags, A Erb, R GrossAbstract:The spin Peltier Effect (SPE) in a junction comprising a gadolinium-iron-garnet (GdIG) slab and a Pt film has been investigated around the magnetization compensation temperature of GdIG by means of the lock-in thermography method. When a charge current is applied to the Pt layer, a spin current is generated across the Pt/GdIG interface via the spin Hall Effect in Pt. This spin current induces a heat current and a measurable temperature change near the Pt/GdIG interface due to the SPE. The SPE signal in the Pt/GdIG junction shows a sign change around the magnetization compensation temperature, demonstrating the similar temperature dependence of the SPE and the spin Seebeck Effect for the Pt/GdIG hybrid system.
Ph J Anserme - One of the best experts on this subject based on the ideXlab platform.
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spin dependent Peltier Effect of perpendicular currents in multilayered nanowires
Physical Review B, 2006Co-Authors: L Gravie, S Serranoguisa, F Reuse, Ph J AnsermeAbstract:Reference EPFL-ARTICLE-147569doi:10.1103/PhysRevB.73.052410View record in Web of Science Record created on 2010-03-23, modified on 2017-05-12
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spin dependent Peltier Effect in co cu multilayer nanowires
Journal of Applied Physics, 2005Co-Authors: L Gravie, S Serranoguisa, Ph J AnsermeAbstract:Heat transport perpendicular to the plane of magnetic multilayers is monitored with ac temperature gradients in the presence of a direct charge current. A very strong dependence on the applied magnetic field of the voltage response to the ac gradient is observed using Co∕Cu multilayered nanowires. The Effect is interpreted as a Peltier Effect for a one-dimensional heat flux.
