The Experts below are selected from a list of 1620 Experts worldwide ranked by ideXlab platform
William P. King - One of the best experts on this subject based on the ideXlab platform.
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heterogeneous nanometer scale joule and Peltier Effects in sub 25 nm thin phase change memory devices
Journal of Applied Physics, 2014Co-Authors: Kyle L. Grosse, Eric Pop, William P. KingAbstract:We measure heterogeneous power dissipation in phase change memory (PCM) films of 11 and 22 nm thin Ge2Sb2Te5 (GST) by scanning Joule expansion microscopy (SJEM), with sub-50 nm spatial and ∼0.2 K temperature resolution. The heterogeneous Joule and Peltier Effects are explained using a finite element analysis (FEA) model with a mixture of hexagonal close-packed and face-centered cubic GST phases. Transfer length method measurements and effective media theory calculations yield the GST resistivity, GST-TiW contact resistivity, and crystal fraction of the GST films at different annealing temperatures. Further comparison of SJEM measurements and FEA modeling also predicts the thermopower of thin GST films. These measurements of nanometer-scale Joule, thermoelectric, and interface Effects in PCM films could lead to energy-efficient designs of highly scaled PCM technology.
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Nanometer-scale temperature imaging for independent observation of Joule and Peltier Effects in phase change memory devices
Review of Scientific Instruments, 2014Co-Authors: Kyle L. Grosse, Eric Pop, William P. KingAbstract:This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric Effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric Effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier Effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K−1. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.
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direct observation of nanometer scale joule and Peltier Effects in phase change memory devices
arXiv: Mesoscale and Nanoscale Physics, 2013Co-Authors: Kyle L. Grosse, William P. King, Feng Xiong, Sungduk Hong, Eric PopAbstract:We measure power dissipation in phase change memory (PCM) devices by scanning Joule ex-pansion microscopy (SJEM) with ~50 nm spatial and 0.2 K temperature resolution. The temperature rise in the Ge2Sb2Te5 (GST) is dominated by Joule heating, but at the GST-TiW contacts it is a combination of Peltier and current crowding Effects. Comparison of SJEM and electrical characterization with simulations of the PCM devices uncovers a thermopower ~350 uV/K for 25 nm thick films of face centered-cubic crystallized GST, and contact resistance ~2.0 x 10^-8 Ohm-m2. Knowledge of such nanoscale Joule, Peltier, and current crowding Effects is essential for energy-efficient design of future PCM technology.
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direct observation of nanometer scale joule and Peltier Effects in phase change memory devices
Applied Physics Letters, 2013Co-Authors: Kyle L. Grosse, William P. King, Feng Xiong, Sungduk Hong, Eric PopAbstract:We measure power dissipation in phase change memory (PCM) devices by scanning Joule expansion microscopy (SJEM) with ∼50 nm spatial and 0.2 K temperature resolution. The temperature rise in the Ge2Sb2Te5 (GST) is dominated by Joule heating, but at the GST-TiW contacts it is a combination of Peltier and current crowding Effects. Comparison of SJEM and electrical measurements with simulations of the PCM devices uncovers a thermopower of ∼350 μV K−1 and a contact resistance of ∼2.0 × 10−8 Ω m2 (to TiW) for 25 nm thick films of face centered-cubic crystalline GST. Knowledge of such nanometer-scale Joule, Peltier, and current crowding Effects is essential for energy-efficient design of future PCM technology.
Eric Pop - One of the best experts on this subject based on the ideXlab platform.
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heterogeneous nanometer scale joule and Peltier Effects in sub 25 nm thin phase change memory devices
Journal of Applied Physics, 2014Co-Authors: Kyle L. Grosse, Eric Pop, William P. KingAbstract:We measure heterogeneous power dissipation in phase change memory (PCM) films of 11 and 22 nm thin Ge2Sb2Te5 (GST) by scanning Joule expansion microscopy (SJEM), with sub-50 nm spatial and ∼0.2 K temperature resolution. The heterogeneous Joule and Peltier Effects are explained using a finite element analysis (FEA) model with a mixture of hexagonal close-packed and face-centered cubic GST phases. Transfer length method measurements and effective media theory calculations yield the GST resistivity, GST-TiW contact resistivity, and crystal fraction of the GST films at different annealing temperatures. Further comparison of SJEM measurements and FEA modeling also predicts the thermopower of thin GST films. These measurements of nanometer-scale Joule, thermoelectric, and interface Effects in PCM films could lead to energy-efficient designs of highly scaled PCM technology.
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Nanometer-scale temperature imaging for independent observation of Joule and Peltier Effects in phase change memory devices
Review of Scientific Instruments, 2014Co-Authors: Kyle L. Grosse, Eric Pop, William P. KingAbstract:This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric Effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric Effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier Effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K−1. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.
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direct observation of nanometer scale joule and Peltier Effects in phase change memory devices
arXiv: Mesoscale and Nanoscale Physics, 2013Co-Authors: Kyle L. Grosse, William P. King, Feng Xiong, Sungduk Hong, Eric PopAbstract:We measure power dissipation in phase change memory (PCM) devices by scanning Joule ex-pansion microscopy (SJEM) with ~50 nm spatial and 0.2 K temperature resolution. The temperature rise in the Ge2Sb2Te5 (GST) is dominated by Joule heating, but at the GST-TiW contacts it is a combination of Peltier and current crowding Effects. Comparison of SJEM and electrical characterization with simulations of the PCM devices uncovers a thermopower ~350 uV/K for 25 nm thick films of face centered-cubic crystallized GST, and contact resistance ~2.0 x 10^-8 Ohm-m2. Knowledge of such nanoscale Joule, Peltier, and current crowding Effects is essential for energy-efficient design of future PCM technology.
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direct observation of nanometer scale joule and Peltier Effects in phase change memory devices
Applied Physics Letters, 2013Co-Authors: Kyle L. Grosse, William P. King, Feng Xiong, Sungduk Hong, Eric PopAbstract:We measure power dissipation in phase change memory (PCM) devices by scanning Joule expansion microscopy (SJEM) with ∼50 nm spatial and 0.2 K temperature resolution. The temperature rise in the Ge2Sb2Te5 (GST) is dominated by Joule heating, but at the GST-TiW contacts it is a combination of Peltier and current crowding Effects. Comparison of SJEM and electrical measurements with simulations of the PCM devices uncovers a thermopower of ∼350 μV K−1 and a contact resistance of ∼2.0 × 10−8 Ω m2 (to TiW) for 25 nm thick films of face centered-cubic crystalline GST. Knowledge of such nanometer-scale Joule, Peltier, and current crowding Effects is essential for energy-efficient design of future PCM technology.
Kyle L. Grosse - One of the best experts on this subject based on the ideXlab platform.
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heterogeneous nanometer scale joule and Peltier Effects in sub 25 nm thin phase change memory devices
Journal of Applied Physics, 2014Co-Authors: Kyle L. Grosse, Eric Pop, William P. KingAbstract:We measure heterogeneous power dissipation in phase change memory (PCM) films of 11 and 22 nm thin Ge2Sb2Te5 (GST) by scanning Joule expansion microscopy (SJEM), with sub-50 nm spatial and ∼0.2 K temperature resolution. The heterogeneous Joule and Peltier Effects are explained using a finite element analysis (FEA) model with a mixture of hexagonal close-packed and face-centered cubic GST phases. Transfer length method measurements and effective media theory calculations yield the GST resistivity, GST-TiW contact resistivity, and crystal fraction of the GST films at different annealing temperatures. Further comparison of SJEM measurements and FEA modeling also predicts the thermopower of thin GST films. These measurements of nanometer-scale Joule, thermoelectric, and interface Effects in PCM films could lead to energy-efficient designs of highly scaled PCM technology.
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Nanometer-scale temperature imaging for independent observation of Joule and Peltier Effects in phase change memory devices
Review of Scientific Instruments, 2014Co-Authors: Kyle L. Grosse, Eric Pop, William P. KingAbstract:This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric Effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric Effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier Effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K−1. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.
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direct observation of nanometer scale joule and Peltier Effects in phase change memory devices
arXiv: Mesoscale and Nanoscale Physics, 2013Co-Authors: Kyle L. Grosse, William P. King, Feng Xiong, Sungduk Hong, Eric PopAbstract:We measure power dissipation in phase change memory (PCM) devices by scanning Joule ex-pansion microscopy (SJEM) with ~50 nm spatial and 0.2 K temperature resolution. The temperature rise in the Ge2Sb2Te5 (GST) is dominated by Joule heating, but at the GST-TiW contacts it is a combination of Peltier and current crowding Effects. Comparison of SJEM and electrical characterization with simulations of the PCM devices uncovers a thermopower ~350 uV/K for 25 nm thick films of face centered-cubic crystallized GST, and contact resistance ~2.0 x 10^-8 Ohm-m2. Knowledge of such nanoscale Joule, Peltier, and current crowding Effects is essential for energy-efficient design of future PCM technology.
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direct observation of nanometer scale joule and Peltier Effects in phase change memory devices
Applied Physics Letters, 2013Co-Authors: Kyle L. Grosse, William P. King, Feng Xiong, Sungduk Hong, Eric PopAbstract:We measure power dissipation in phase change memory (PCM) devices by scanning Joule expansion microscopy (SJEM) with ∼50 nm spatial and 0.2 K temperature resolution. The temperature rise in the Ge2Sb2Te5 (GST) is dominated by Joule heating, but at the GST-TiW contacts it is a combination of Peltier and current crowding Effects. Comparison of SJEM and electrical measurements with simulations of the PCM devices uncovers a thermopower of ∼350 μV K−1 and a contact resistance of ∼2.0 × 10−8 Ω m2 (to TiW) for 25 nm thick films of face centered-cubic crystalline GST. Knowledge of such nanometer-scale Joule, Peltier, and current crowding Effects is essential for energy-efficient design of future PCM technology.
M Pasquale - One of the best experts on this subject based on the ideXlab platform.
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nonequilibrium thermodynamics of the spin seebeck and spin Peltier Effects
Physical Review B, 2016Co-Authors: Vittorio Basso, E Ferraro, A Magni, Alessandro Sola, Michaela Kuepferling, M PasqualeAbstract:We study the problem of magnetization and heat currents and their associated thermodynamic forces in a magnetic system by focusing on the magnetization transport in ferromagnetic insulators like YIG. The resulting theory is applied to the longitudinal spin Seebeck and spin Peltier Effects. By focusing on the specific geometry with one ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ (YIG) layer and one Pt layer, we obtain the optimal conditions for generating large magnetization currents into Pt or large temperature Effects in YIG. The theoretical predictions are compared with experiments from the literature permitting to derive the values of the thermomagnetic coefficients of YIG: the magnetization diffusion length ${l}_{M}\ensuremath{\sim}0.4\phantom{\rule{0.16em}{0ex}}\ensuremath{\mu}\mathrm{m}$ and the absolute thermomagnetic power coefficient ${\ensuremath{\epsilon}}_{M}\ensuremath{\sim}{10}^{\ensuremath{-}2}\phantom{\rule{4pt}{0ex}}{\mathrm{TK}}^{\ensuremath{-}1}$.
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thermodynamics of the heat currents in the longitudinal spin seebeck and spin Peltier Effects
arXiv: Materials Science, 2015Co-Authors: Vittorio Basso, E Ferraro, A Magni, Alessandro Sola, Michaela Kuepferling, M PasqualeAbstract:We employ the non-equilibrium thermodynamics of currents and forces to describe the heat transport caused by a spin current in a Pt/YIG bilayer. By starting from the constitutive equations of the magnetization currents in both Pt and YIG, we derive the magnetization potentials and currents. We apply the theory to the spin Peltier experiments in which a spin current, generated by the spin Hall effect in Pt, is injected into YIG. We find that efficient injection is obtained when: i) the thickness of each layer is larger than its diffusion length: $t_{Pt} > l_{Pt}$ and $t_{YIG} > l_{YIG}$ and ii) the ratio $(l_{Pt}/\tau_{Pt})/(l_{YIG}/\tau_{YIG})$ is small, where $\tau_i$ is the time constant of the intrinsic damping ($i=Pt, YIG$). We finally derive the temperature profile in adiabatic conditions. The scale of the effect is given by the parameter $\Delta T_{SH}$ which is proportional to the electric current in Pt. Using known parameters for Pt and YIG we estimate $\Delta T_{SH}/j_e = 4 \cdot 10^{-13}$ K A$^{-1}$m$^2$. This value is of the same order of magnitude of the spin Peltier experiments.
Vittorio Basso - One of the best experts on this subject based on the ideXlab platform.
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nonequilibrium thermodynamics of the spin seebeck and spin Peltier Effects
Physical Review B, 2016Co-Authors: Vittorio Basso, E Ferraro, A Magni, Alessandro Sola, Michaela Kuepferling, M PasqualeAbstract:We study the problem of magnetization and heat currents and their associated thermodynamic forces in a magnetic system by focusing on the magnetization transport in ferromagnetic insulators like YIG. The resulting theory is applied to the longitudinal spin Seebeck and spin Peltier Effects. By focusing on the specific geometry with one ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ (YIG) layer and one Pt layer, we obtain the optimal conditions for generating large magnetization currents into Pt or large temperature Effects in YIG. The theoretical predictions are compared with experiments from the literature permitting to derive the values of the thermomagnetic coefficients of YIG: the magnetization diffusion length ${l}_{M}\ensuremath{\sim}0.4\phantom{\rule{0.16em}{0ex}}\ensuremath{\mu}\mathrm{m}$ and the absolute thermomagnetic power coefficient ${\ensuremath{\epsilon}}_{M}\ensuremath{\sim}{10}^{\ensuremath{-}2}\phantom{\rule{4pt}{0ex}}{\mathrm{TK}}^{\ensuremath{-}1}$.
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thermodynamics of the heat currents in the longitudinal spin seebeck and spin Peltier Effects
arXiv: Materials Science, 2015Co-Authors: Vittorio Basso, E Ferraro, A Magni, Alessandro Sola, Michaela Kuepferling, M PasqualeAbstract:We employ the non-equilibrium thermodynamics of currents and forces to describe the heat transport caused by a spin current in a Pt/YIG bilayer. By starting from the constitutive equations of the magnetization currents in both Pt and YIG, we derive the magnetization potentials and currents. We apply the theory to the spin Peltier experiments in which a spin current, generated by the spin Hall effect in Pt, is injected into YIG. We find that efficient injection is obtained when: i) the thickness of each layer is larger than its diffusion length: $t_{Pt} > l_{Pt}$ and $t_{YIG} > l_{YIG}$ and ii) the ratio $(l_{Pt}/\tau_{Pt})/(l_{YIG}/\tau_{YIG})$ is small, where $\tau_i$ is the time constant of the intrinsic damping ($i=Pt, YIG$). We finally derive the temperature profile in adiabatic conditions. The scale of the effect is given by the parameter $\Delta T_{SH}$ which is proportional to the electric current in Pt. Using known parameters for Pt and YIG we estimate $\Delta T_{SH}/j_e = 4 \cdot 10^{-13}$ K A$^{-1}$m$^2$. This value is of the same order of magnitude of the spin Peltier experiments.