I. Lucas - Academia.edu (original) (raw)
Papers by I. Lucas
Resumen del poster presentado a la 19th International Conference on Magnetism celebrada en Korea ... more Resumen del poster presentado a la 19th International Conference on Magnetism celebrada en Korea del 8 al 13 de julio de 2012.
Resumen del trabajo presentado al 14th International Workshop on Magnetism & Superconductivity at... more Resumen del trabajo presentado al 14th International Workshop on Magnetism & Superconductivity at the Nanoscale, celebrado en Coma-Ruga, El Vendrell (Espana) del 1 al 6 de julio de 2018.
Resumen del trabajo presentado al "European Congress and Exhibition on Advanced Materials Pr... more Resumen del trabajo presentado al "European Congress and Exhibition on Advanced Materials Processes" celebrado en Sevilla (Espana) del 8 al 13 de septiembre de 2013.-- et al.
Resumen del poster presentado al 10th International Symposium on Metallic Multilayers (MML), cele... more Resumen del poster presentado al 10th International Symposium on Metallic Multilayers (MML), celebrado en Madrid (Espana) del 17 al 21 de junio de 2019.
Journal of Physics D: Applied Physics, 2018
Since the discovery of the spin Seebeck effect (SSE), much attention has been devoted to the stud... more Since the discovery of the spin Seebeck effect (SSE), much attention has been devoted to the study of the interaction between heat, spin, and charge in magnetic systems. The SSE refers to the generation of a spin current upon the application of a thermal gradient and detected by means of the inverse spin Hall effect. Conversely, the spin Peltier effect (SPE) refers to the generation of a heat current as a result of a spin current induced by the spin Hall effect. Here we report a strong enhancement of both the SSE and SPE in Fe 3 O 4 /Pt multilayered thin films at room temperature as a result of an increased thermo-spin conversion efficiency in the multilayers. These results open the possibility to design thin film heterostructures that may boost the application of thermal spin currents in spintronics.
![Research paper thumbnail of Temperature dependence of the spin Seebeck effect in [Fe3O4/Pt]n multilayers](https://attachments.academia-assets.com/120918073/thumbnails/1.jpg)
](AIP Advances, 2017
We report temperature dependent measurements of the spin Seebeck effect (SSE) in multilayers form... more We report temperature dependent measurements of the spin Seebeck effect (SSE) in multilayers formed by repeated growth of a Fe3O4/Pt bilayer junction. The magnitude of the observed enhancement of the SSE, relative to the SSE in the single bilayer, shows a monotonic increase with decreasing the temperature. This result can be understood by an increase of the characteristic length for spin current transport in the system, in qualitative agreement with the recently observed increase in the magnon diffusion length in Fe3O4 at lower temperatures. Our result suggests that the thermoelectric performance of the SSE in multilayer structures can be further improved by careful choice of materials with suitable spin transport properties.
SPIN, 2017
Terahertz emission spectroscopy (TES) of ultrathin multilayers of magnetic and heavy metals has r... more Terahertz emission spectroscopy (TES) of ultrathin multilayers of magnetic and heavy metals has recently attracted much interest. This method not only provides fundamental insights into photoinduced spin transport and spin–orbit interaction at highest frequencies, but has also paved the way for applications such as efficient and ultrabroadband emitters of terahertz (THz) electromagnetic radiation. So far, predominantly standard ferromagnetic materials have been exploited. Here, by introducing a suitable figure of merit, we systematically compare the strength of THz emission from [Formula: see text]/Pt bilayers with [Formula: see text] being a complex ferro-, ferri- and antiferromagnetic metal, that is, dysprosium cobalt (DyCo5), gadolinium iron (Gd[Formula: see text]Fe[Formula: see text]), magnetite (Fe3O4) and iron rhodium (FeRh). We find that the performance in terms of spin-current generation not only depends on the spin polarization of the magnet’s conduction electrons, but also...
Physical Review B, 2015
Spin Seebeck effects (SSEs) have been investigated in highly crystalline magnetic multilayer [Fe ... more Spin Seebeck effects (SSEs) have been investigated in highly crystalline magnetic multilayer [Fe 3 O 4 /Pt] n films. Voltage as well as power generated by the SSE were found to be significantly enhanced with increasing the number of layers n. This voltage enhancement defies the simple understanding of the SSE and suggests that spin current flowing between the magnetic layers in the thickness direction plays an important role in multilayer SSE systems and the observed voltage enhancement.
Applied Physics Letters, 2016
The dependence of Spin Seebeck effect (SSE) with the thickness of the magnetic materials is studi... more The dependence of Spin Seebeck effect (SSE) with the thickness of the magnetic materials is studied by means of incoherent thermal excitation. The SSE voltage signal in Fe3O4/Pt bilayer structure increases with the magnetic material thickness up to 100 nm, approximately, showing signs of saturation for larger thickness. This dependence is well described in terms of a spin current pumped in the platinum film by the magnon accumulation in the magnetic material. The spin current is generated by a gradient of temperature in the system and detected by the Pt top contact by means of inverse spin Hall effect. Calculations in the frame of the linear response theory adjust with a high degree of accuracy the experimental data, giving a thermal length scale of the magnon accumulation (Λ) of 17 ± 3 nm at 300 K and Λ = 40 ± 10 nm at 70 K.
Applied Physics Letters, 2015
We show here that using spin orbit coupling interactions at a metallic interface it is possible t... more We show here that using spin orbit coupling interactions at a metallic interface it is possible to control the sign of the spin to charge conversion in a spin pumping experiment. Using the intrinsic symmetry of the “Inverse Rashba Edelstein Effect” (IREE) in a Bi/Ag interface, the charge current changes sign when reversing the order of the Ag and Bi stacking. This confirms the IREE nature of the conversion of spin into charge in these interfaces and opens the way to tailoring the spin sensing voltage by an appropriate trilayer sequence.
MRS Proceedings, 2014
ABSTRACTWe present a comparative study of the anomalous Nernst effect (ANE), measured at room tem... more ABSTRACTWe present a comparative study of the anomalous Nernst effect (ANE), measured at room temperature for magnetite thin films deposited on different substrates in order to study the effects induced by the substrate, compressive or tensile strain and structural defects as anti-phase boundaries (APB), on the observed ANE. From our preliminary results we have observed an increase of the measured ANE in the case of compressive strain compared with the tensile one. Moreover our results also suggest that the density of APBs also play an important role in the ANE values.
Sensors and Actuators a-Physical, 2010
The dynamic properties of membranes have been object of many researches since they can be used as... more The dynamic properties of membranes have been object of many researches since they can be used as sensor heads in different devices. Some methods have been proposed to solve the problem of determining the resonance frequencies and their dependence on the stress caused by forces applied on the membrane surface. The problem of the vibrating rectangular membrane under a stress caused by a uniform in-plane force is well known. However, the resonance frequency behaviour when the force is out-of-plane instead of in-plane, is not so well understood and documented. A gradiometer which uses a silicon square membrane with a magnet fixed on it as a sensor head has been developed in a previous work. This device reports a quadratic dependence of the frequency on the outof-plane magnetic force. In this work, simulations to obtain the dependence of the frequency of the fundamental flexural mode on the stress have been performed. It has been studied the influence of in-plane and out-of-plane forces applied to the membrane. As expected, a square root dependence has been found for in-plane forces. Nevertheless, the problem is more complex when out-of plane forces are considered. Out-of-plane forces gives rise to an initial quadratic dependence which turns into a square root dependence from a certain stress value. The quadratic range increases and the rate of change of the frequency decreases as the surface of the magnet fixed on the membrane increases. The study has addressed these problems and both, experimental and simulated results have been compared and a good agreement between experimental and simulated results has been found.
ACS Applied Materials & Interfaces, 2014
We report magnetic and electronic transport measurements across epitaxial bilayers of ferromagnet... more We report magnetic and electronic transport measurements across epitaxial bilayers of ferromagnetic insulator LaCoO 3 and half-metallic ferromagnet La 2/3 Sr 1/3 MnO 3 (LCO/LSMO: 3.5 nm/20 nm) fabricated by a chemical solution method. The I-V curves at room temperature and 4K measured with conducting atomic force microscopy (CAFM) on well-defined patterned areas exhibit the typical features of a tunneling process. The curves have been fitted to the Simmons model to determine the height (φ) and width (s) of the insulating LCO barrier. The results yield φ = 0.40 ± 0.05 eV (0.50 ± 0.01 eV) at room temperature (4K) and s = 3 nm, in good agreement with the structural analysis. Our results demonstrate that this chemical method is able to produce epitaxial heterostructures with the quality required for this type of fundamental studies and applications.
Sensors and Actuators A: Physical, 2010
Mechanically resonant ferromagnetic MEMS sensors intended for magnetic field gradient measurement... more Mechanically resonant ferromagnetic MEMS sensors intended for magnetic field gradient measurements are presented. Suspended quad-beams with proof mass have been designed to improve their sensitivity and to simplify the detection. Fabricated devices exhibit the compact size of current MEMS technologies and are built within a simple deep-reactive-ion etching-based process. Nanometer-resolution detection based on optical interferometry and signal processing techniques have
Sensor Letters, 2009
ABSTRACT In this work a magnetic field gradiometer device has been developed. This device is not ... more ABSTRACT In this work a magnetic field gradiometer device has been developed. This device is not composed by two sensors separated a certain distance but by a single-sensor device which measures the real gradient value just at the point where it is wanted to be measured. The experimental set-up consists of a sensor head (a membrane with a fixed permanent magnet on it) vibrating at its resonance frequency, due to an alternating magnetic field gradient. Detection is performed using an optoelectronic method. Two different measurement techniques have been used: frequency measurements (the resonance frequency is measured for every external magnetic field gradient value) and amplitude measurements (the signal amplitude is measured without changing the resonance frequency obtained without an external magnetic field gradient applied). The mechanical stresses of the membrane are related with the dependence of both magnitudes (frequency and amplitude) on the external magnetic field gradient. The minimum and maximum value of the resonance frequency and signal amplitude respectively, correspond with magnetic forces equal to the magnet weight of the sensor head. This prototype shows a noise-limited sensitivity of 2 Gauss/m/√Hz at zero gradient. This device could be used also as a magnetic susceptometer.
Journal of Magnetism and Magnetic Materials, 2007
In this work we present a study of the pinning field and coercivity of electrodeposited soft magn... more In this work we present a study of the pinning field and coercivity of electrodeposited soft magnetic ðCo 76 P 24 =Co 85 P 15 Þ N multilayered films. For f o1 kHz, a linear dependence of pinning field on N is reported, linear dependence which is valid as long as the films do not have a perpendicular contribution to the magnetic anisotropy. This behavior can be associated to the pinning of domain walls in the interfaces between the layers. For f 41 kHz, the magnetic behavior is controlled by eddy currents, being the dependence of coercivity on frequency independent of N.
Applied Physics Letters, 2013
We report the experimental observation of the spin Seebeck effect in magnetite thin films. The si... more We report the experimental observation of the spin Seebeck effect in magnetite thin films. The signal observed at temperatures above the Verwey transition is a contribution from both the anomalous Nernst (ANE) and spin Seebeck (SSE) effects. The contribution from the ANE of the Fe3O4 layer to the SSE is found to be negligible due to the resistivity difference between Fe3O4 and Pt layers. Below the Verwey transition, the SSE is free from the ANE of the ferromagnetic layer and it is also found to dominate over the ANE due to magnetic proximity effect on the Pt layer.
Resumen del poster presentado a la 19th International Conference on Magnetism celebrada en Korea ... more Resumen del poster presentado a la 19th International Conference on Magnetism celebrada en Korea del 8 al 13 de julio de 2012.
Resumen del trabajo presentado al 14th International Workshop on Magnetism & Superconductivity at... more Resumen del trabajo presentado al 14th International Workshop on Magnetism & Superconductivity at the Nanoscale, celebrado en Coma-Ruga, El Vendrell (Espana) del 1 al 6 de julio de 2018.
Resumen del trabajo presentado al "European Congress and Exhibition on Advanced Materials Pr... more Resumen del trabajo presentado al "European Congress and Exhibition on Advanced Materials Processes" celebrado en Sevilla (Espana) del 8 al 13 de septiembre de 2013.-- et al.
Resumen del poster presentado al 10th International Symposium on Metallic Multilayers (MML), cele... more Resumen del poster presentado al 10th International Symposium on Metallic Multilayers (MML), celebrado en Madrid (Espana) del 17 al 21 de junio de 2019.
Journal of Physics D: Applied Physics, 2018
Since the discovery of the spin Seebeck effect (SSE), much attention has been devoted to the stud... more Since the discovery of the spin Seebeck effect (SSE), much attention has been devoted to the study of the interaction between heat, spin, and charge in magnetic systems. The SSE refers to the generation of a spin current upon the application of a thermal gradient and detected by means of the inverse spin Hall effect. Conversely, the spin Peltier effect (SPE) refers to the generation of a heat current as a result of a spin current induced by the spin Hall effect. Here we report a strong enhancement of both the SSE and SPE in Fe 3 O 4 /Pt multilayered thin films at room temperature as a result of an increased thermo-spin conversion efficiency in the multilayers. These results open the possibility to design thin film heterostructures that may boost the application of thermal spin currents in spintronics.
AIP Advances, 2017
We report temperature dependent measurements of the spin Seebeck effect (SSE) in multilayers form... more We report temperature dependent measurements of the spin Seebeck effect (SSE) in multilayers formed by repeated growth of a Fe3O4/Pt bilayer junction. The magnitude of the observed enhancement of the SSE, relative to the SSE in the single bilayer, shows a monotonic increase with decreasing the temperature. This result can be understood by an increase of the characteristic length for spin current transport in the system, in qualitative agreement with the recently observed increase in the magnon diffusion length in Fe3O4 at lower temperatures. Our result suggests that the thermoelectric performance of the SSE in multilayer structures can be further improved by careful choice of materials with suitable spin transport properties.
SPIN, 2017
Terahertz emission spectroscopy (TES) of ultrathin multilayers of magnetic and heavy metals has r... more Terahertz emission spectroscopy (TES) of ultrathin multilayers of magnetic and heavy metals has recently attracted much interest. This method not only provides fundamental insights into photoinduced spin transport and spin–orbit interaction at highest frequencies, but has also paved the way for applications such as efficient and ultrabroadband emitters of terahertz (THz) electromagnetic radiation. So far, predominantly standard ferromagnetic materials have been exploited. Here, by introducing a suitable figure of merit, we systematically compare the strength of THz emission from [Formula: see text]/Pt bilayers with [Formula: see text] being a complex ferro-, ferri- and antiferromagnetic metal, that is, dysprosium cobalt (DyCo5), gadolinium iron (Gd[Formula: see text]Fe[Formula: see text]), magnetite (Fe3O4) and iron rhodium (FeRh). We find that the performance in terms of spin-current generation not only depends on the spin polarization of the magnet’s conduction electrons, but also...
Physical Review B, 2015
Spin Seebeck effects (SSEs) have been investigated in highly crystalline magnetic multilayer [Fe ... more Spin Seebeck effects (SSEs) have been investigated in highly crystalline magnetic multilayer [Fe 3 O 4 /Pt] n films. Voltage as well as power generated by the SSE were found to be significantly enhanced with increasing the number of layers n. This voltage enhancement defies the simple understanding of the SSE and suggests that spin current flowing between the magnetic layers in the thickness direction plays an important role in multilayer SSE systems and the observed voltage enhancement.
Applied Physics Letters, 2016
The dependence of Spin Seebeck effect (SSE) with the thickness of the magnetic materials is studi... more The dependence of Spin Seebeck effect (SSE) with the thickness of the magnetic materials is studied by means of incoherent thermal excitation. The SSE voltage signal in Fe3O4/Pt bilayer structure increases with the magnetic material thickness up to 100 nm, approximately, showing signs of saturation for larger thickness. This dependence is well described in terms of a spin current pumped in the platinum film by the magnon accumulation in the magnetic material. The spin current is generated by a gradient of temperature in the system and detected by the Pt top contact by means of inverse spin Hall effect. Calculations in the frame of the linear response theory adjust with a high degree of accuracy the experimental data, giving a thermal length scale of the magnon accumulation (Λ) of 17 ± 3 nm at 300 K and Λ = 40 ± 10 nm at 70 K.
Applied Physics Letters, 2015
We show here that using spin orbit coupling interactions at a metallic interface it is possible t... more We show here that using spin orbit coupling interactions at a metallic interface it is possible to control the sign of the spin to charge conversion in a spin pumping experiment. Using the intrinsic symmetry of the “Inverse Rashba Edelstein Effect” (IREE) in a Bi/Ag interface, the charge current changes sign when reversing the order of the Ag and Bi stacking. This confirms the IREE nature of the conversion of spin into charge in these interfaces and opens the way to tailoring the spin sensing voltage by an appropriate trilayer sequence.
MRS Proceedings, 2014
ABSTRACTWe present a comparative study of the anomalous Nernst effect (ANE), measured at room tem... more ABSTRACTWe present a comparative study of the anomalous Nernst effect (ANE), measured at room temperature for magnetite thin films deposited on different substrates in order to study the effects induced by the substrate, compressive or tensile strain and structural defects as anti-phase boundaries (APB), on the observed ANE. From our preliminary results we have observed an increase of the measured ANE in the case of compressive strain compared with the tensile one. Moreover our results also suggest that the density of APBs also play an important role in the ANE values.
Sensors and Actuators a-Physical, 2010
The dynamic properties of membranes have been object of many researches since they can be used as... more The dynamic properties of membranes have been object of many researches since they can be used as sensor heads in different devices. Some methods have been proposed to solve the problem of determining the resonance frequencies and their dependence on the stress caused by forces applied on the membrane surface. The problem of the vibrating rectangular membrane under a stress caused by a uniform in-plane force is well known. However, the resonance frequency behaviour when the force is out-of-plane instead of in-plane, is not so well understood and documented. A gradiometer which uses a silicon square membrane with a magnet fixed on it as a sensor head has been developed in a previous work. This device reports a quadratic dependence of the frequency on the outof-plane magnetic force. In this work, simulations to obtain the dependence of the frequency of the fundamental flexural mode on the stress have been performed. It has been studied the influence of in-plane and out-of-plane forces applied to the membrane. As expected, a square root dependence has been found for in-plane forces. Nevertheless, the problem is more complex when out-of plane forces are considered. Out-of-plane forces gives rise to an initial quadratic dependence which turns into a square root dependence from a certain stress value. The quadratic range increases and the rate of change of the frequency decreases as the surface of the magnet fixed on the membrane increases. The study has addressed these problems and both, experimental and simulated results have been compared and a good agreement between experimental and simulated results has been found.
ACS Applied Materials & Interfaces, 2014
We report magnetic and electronic transport measurements across epitaxial bilayers of ferromagnet... more We report magnetic and electronic transport measurements across epitaxial bilayers of ferromagnetic insulator LaCoO 3 and half-metallic ferromagnet La 2/3 Sr 1/3 MnO 3 (LCO/LSMO: 3.5 nm/20 nm) fabricated by a chemical solution method. The I-V curves at room temperature and 4K measured with conducting atomic force microscopy (CAFM) on well-defined patterned areas exhibit the typical features of a tunneling process. The curves have been fitted to the Simmons model to determine the height (φ) and width (s) of the insulating LCO barrier. The results yield φ = 0.40 ± 0.05 eV (0.50 ± 0.01 eV) at room temperature (4K) and s = 3 nm, in good agreement with the structural analysis. Our results demonstrate that this chemical method is able to produce epitaxial heterostructures with the quality required for this type of fundamental studies and applications.
Sensors and Actuators A: Physical, 2010
Mechanically resonant ferromagnetic MEMS sensors intended for magnetic field gradient measurement... more Mechanically resonant ferromagnetic MEMS sensors intended for magnetic field gradient measurements are presented. Suspended quad-beams with proof mass have been designed to improve their sensitivity and to simplify the detection. Fabricated devices exhibit the compact size of current MEMS technologies and are built within a simple deep-reactive-ion etching-based process. Nanometer-resolution detection based on optical interferometry and signal processing techniques have
Sensor Letters, 2009
ABSTRACT In this work a magnetic field gradiometer device has been developed. This device is not ... more ABSTRACT In this work a magnetic field gradiometer device has been developed. This device is not composed by two sensors separated a certain distance but by a single-sensor device which measures the real gradient value just at the point where it is wanted to be measured. The experimental set-up consists of a sensor head (a membrane with a fixed permanent magnet on it) vibrating at its resonance frequency, due to an alternating magnetic field gradient. Detection is performed using an optoelectronic method. Two different measurement techniques have been used: frequency measurements (the resonance frequency is measured for every external magnetic field gradient value) and amplitude measurements (the signal amplitude is measured without changing the resonance frequency obtained without an external magnetic field gradient applied). The mechanical stresses of the membrane are related with the dependence of both magnitudes (frequency and amplitude) on the external magnetic field gradient. The minimum and maximum value of the resonance frequency and signal amplitude respectively, correspond with magnetic forces equal to the magnet weight of the sensor head. This prototype shows a noise-limited sensitivity of 2 Gauss/m/√Hz at zero gradient. This device could be used also as a magnetic susceptometer.
Journal of Magnetism and Magnetic Materials, 2007
In this work we present a study of the pinning field and coercivity of electrodeposited soft magn... more In this work we present a study of the pinning field and coercivity of electrodeposited soft magnetic ðCo 76 P 24 =Co 85 P 15 Þ N multilayered films. For f o1 kHz, a linear dependence of pinning field on N is reported, linear dependence which is valid as long as the films do not have a perpendicular contribution to the magnetic anisotropy. This behavior can be associated to the pinning of domain walls in the interfaces between the layers. For f 41 kHz, the magnetic behavior is controlled by eddy currents, being the dependence of coercivity on frequency independent of N.
Applied Physics Letters, 2013
We report the experimental observation of the spin Seebeck effect in magnetite thin films. The si... more We report the experimental observation of the spin Seebeck effect in magnetite thin films. The signal observed at temperatures above the Verwey transition is a contribution from both the anomalous Nernst (ANE) and spin Seebeck (SSE) effects. The contribution from the ANE of the Fe3O4 layer to the SSE is found to be negligible due to the resistivity difference between Fe3O4 and Pt layers. Below the Verwey transition, the SSE is free from the ANE of the ferromagnetic layer and it is also found to dominate over the ANE due to magnetic proximity effect on the Pt layer.