Pub Date : 2023-07-25DOI: 10.3390/magnetochemistry9080191
I. Benguettat-El Mokhtari, D. Schmool
This review article aims to provide a comprehensive overview of recent FMR studies on magnetic oxide nanoparticles and their potential applications. The use of the FMR technique is a powerful tool to study the magnetic properties of magnetic nanoparticles and can provide valuable information on their behavior. For this, we will start by discussing the purpose of these magnetic nanoparticles and their application in various fields, including biomedical applications, energy storage, and environmental remediation. We will then discuss the methods used to prepare magnetic nanoparticles and the theory behind FMR including the superparamagnetic effect. Additionally, we will present the most recent studies on FMR for magnetic oxide nanoparticles by highlighting the effect of temperature and doping on the magnetic properties of these nanoparticles.
{"title":"Ferromagnetic Resonance in Magnetic Oxide Nanoparticules: A Short Review of Theory and Experiment","authors":"I. Benguettat-El Mokhtari, D. Schmool","doi":"10.3390/magnetochemistry9080191","DOIUrl":"https://doi.org/10.3390/magnetochemistry9080191","url":null,"abstract":"This review article aims to provide a comprehensive overview of recent FMR studies on magnetic oxide nanoparticles and their potential applications. The use of the FMR technique is a powerful tool to study the magnetic properties of magnetic nanoparticles and can provide valuable information on their behavior. For this, we will start by discussing the purpose of these magnetic nanoparticles and their application in various fields, including biomedical applications, energy storage, and environmental remediation. We will then discuss the methods used to prepare magnetic nanoparticles and the theory behind FMR including the superparamagnetic effect. Additionally, we will present the most recent studies on FMR for magnetic oxide nanoparticles by highlighting the effect of temperature and doping on the magnetic properties of these nanoparticles.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45367738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-22DOI: 10.3390/magnetochemistry9070190
Fabio Manna, Mariangela Oggianu, N. Avarvari, M. L. Mercuri
Lanthanide metal–organic frameworks (Ln-MOFs) showing single-molecule magnet (SMM) properties are an ever-growing family of materials where the magnetic properties can be tuned by various interrelated parameters, such as the coordinated solvent, temperature, organic linkers, lanthanide ions and their coordination environment. An overview of the general synthetic methodologies to access MOFs/Ln-MOFs and the peculiarities and parameters to control and/or fine-tune their SMM behavior is herein presented. Additionally, diverse challenging strategies for inducing SMM/SIM behavior in an Ln-MOF are discussed, involving redox activity and chirality. Furthermore, intriguing physical phenomena such as the CISS effect and CPL are also highlighted.
{"title":"Lanthanide-Based Metal–Organic Frameworks with Single-Molecule Magnet Properties","authors":"Fabio Manna, Mariangela Oggianu, N. Avarvari, M. L. Mercuri","doi":"10.3390/magnetochemistry9070190","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070190","url":null,"abstract":"Lanthanide metal–organic frameworks (Ln-MOFs) showing single-molecule magnet (SMM) properties are an ever-growing family of materials where the magnetic properties can be tuned by various interrelated parameters, such as the coordinated solvent, temperature, organic linkers, lanthanide ions and their coordination environment. An overview of the general synthetic methodologies to access MOFs/Ln-MOFs and the peculiarities and parameters to control and/or fine-tune their SMM behavior is herein presented. Additionally, diverse challenging strategies for inducing SMM/SIM behavior in an Ln-MOF are discussed, involving redox activity and chirality. Furthermore, intriguing physical phenomena such as the CISS effect and CPL are also highlighted.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43903563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.3390/magnetochemistry9070189
Susana Aberturas, J. Olazagoitia, M. A. García, Antonio Hernando
In the automobile sector, energy recovery and sustainability are becoming more and more important, and energy-harvesting suspension systems (EHSAs) have a lot of promise to improve vehicle efficiency. This investigation expands on prior work that investigated the viability of an EHSA that uses permanent magnets and amorphous core coils. The performance of the proposed system is demonstrated and enhanced in the current study through the development and optimization of a prototype. A thorough testing of the prototype is performed to determine design improvements for boosting the system’s overall performance and to quantify the recovered energy. In previous work, a method was proposed to find the dependence of the magnetic flux with the relative position between the primary and secondary elements to obtain the optimal position for the system. This method is applied to optimize the energy harvesting coil by testing different configurations in terms of the placement and type of amorphous or nonamorphous core inside the energy harvesting coil. This is a crucial area of attention in order to maximize energy recovery while solving the low-frequency problem that suspension systems have (on the order of 10 Hz).
{"title":"Enhanced Energy Recovery in Magnetic Energy-Harvesting Shock Absorbers Using Soft Magnetic Materials","authors":"Susana Aberturas, J. Olazagoitia, M. A. García, Antonio Hernando","doi":"10.3390/magnetochemistry9070189","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070189","url":null,"abstract":"In the automobile sector, energy recovery and sustainability are becoming more and more important, and energy-harvesting suspension systems (EHSAs) have a lot of promise to improve vehicle efficiency. This investigation expands on prior work that investigated the viability of an EHSA that uses permanent magnets and amorphous core coils. The performance of the proposed system is demonstrated and enhanced in the current study through the development and optimization of a prototype. A thorough testing of the prototype is performed to determine design improvements for boosting the system’s overall performance and to quantify the recovered energy. In previous work, a method was proposed to find the dependence of the magnetic flux with the relative position between the primary and secondary elements to obtain the optimal position for the system. This method is applied to optimize the energy harvesting coil by testing different configurations in terms of the placement and type of amorphous or nonamorphous core inside the energy harvesting coil. This is a crucial area of attention in order to maximize energy recovery while solving the low-frequency problem that suspension systems have (on the order of 10 Hz).","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42958858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-19DOI: 10.3390/magnetochemistry9070188
K. Sarkar, M. Jordan, A. Kebede, Steve Kriske, Frank Wise, Dhananjay Kumar
The magnetocaloric effect (MCE) in iron (Fe) nanoparticles incorporated within a titanium nitride (TiN) thin-film matrix grown using pulsed laser deposition (PLD) is investigated in this study. The study demonstrates the ability to control the entropy change across the magnetic phase transition by varying the size of the Fe nanoparticles. The structural characterization carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and scanning transmission electron (TEM) showed that TiN films are (111) textured, while the Fe-particles are mostly spherical in shapes, are single-crystalline, and have a coherent structure with the surrounding TiN thin-film matrix. The TiN thin-film matrix was chosen as a spacer layer since it is nonmagnetic, is highly corrosion-resistive, and can serve as an excellent conduit for extracting heat due to its high thermal conductivity (11 W/m K). The magnetic properties of Fe–TiN systems were investigated using a superconducting quantum interference device (SQUID) magnetometer. In-plane magnetic fields were applied to record magnetization versus field (M–H) and magnetization versus temperature (M–T) curves. The results showed that the Fe–TiN heterostructure system exhibits a substantial isothermal entropy change (ΔS) over a wide temperature range, encompassing room temperature to the blocking temperature of the Fe nanoparticles. Using Maxwell’s relation and analyzing magnetization–temperature data under different magnetic fields, quantitative insights into the isothermal entropy change (ΔS) and magnetocaloric effect (MCE) were obtained for the Fe–TiN heterostructure system. The study points out a considerable negative change in ΔS that reaches up to 0.2 J/kg K at 0.2 T and 300 K for the samples with a nanoparticle size on the order of 7 nm. Comparative analysis revealed that Fe nanoparticle samples demonstrate higher refrigeration capacity (RC) in comparison to Fe thin-film multilayer samples, with the RC increasing as the Fe particle size decreases. These findings provide valuable insights into the potential application of Fe–TiN heterostructures in solid-state cooling technologies, highlighting their enhanced magnetocaloric properties.
{"title":"Enhanced Magnetic Cooling through Tailoring the Size-Dependent Magnetocaloric Effect of Iron Nanoparticles Embedded in Titanium Nitride Thin Films","authors":"K. Sarkar, M. Jordan, A. Kebede, Steve Kriske, Frank Wise, Dhananjay Kumar","doi":"10.3390/magnetochemistry9070188","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070188","url":null,"abstract":"The magnetocaloric effect (MCE) in iron (Fe) nanoparticles incorporated within a titanium nitride (TiN) thin-film matrix grown using pulsed laser deposition (PLD) is investigated in this study. The study demonstrates the ability to control the entropy change across the magnetic phase transition by varying the size of the Fe nanoparticles. The structural characterization carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and scanning transmission electron (TEM) showed that TiN films are (111) textured, while the Fe-particles are mostly spherical in shapes, are single-crystalline, and have a coherent structure with the surrounding TiN thin-film matrix. The TiN thin-film matrix was chosen as a spacer layer since it is nonmagnetic, is highly corrosion-resistive, and can serve as an excellent conduit for extracting heat due to its high thermal conductivity (11 W/m K). The magnetic properties of Fe–TiN systems were investigated using a superconducting quantum interference device (SQUID) magnetometer. In-plane magnetic fields were applied to record magnetization versus field (M–H) and magnetization versus temperature (M–T) curves. The results showed that the Fe–TiN heterostructure system exhibits a substantial isothermal entropy change (ΔS) over a wide temperature range, encompassing room temperature to the blocking temperature of the Fe nanoparticles. Using Maxwell’s relation and analyzing magnetization–temperature data under different magnetic fields, quantitative insights into the isothermal entropy change (ΔS) and magnetocaloric effect (MCE) were obtained for the Fe–TiN heterostructure system. The study points out a considerable negative change in ΔS that reaches up to 0.2 J/kg K at 0.2 T and 300 K for the samples with a nanoparticle size on the order of 7 nm. Comparative analysis revealed that Fe nanoparticle samples demonstrate higher refrigeration capacity (RC) in comparison to Fe thin-film multilayer samples, with the RC increasing as the Fe particle size decreases. These findings provide valuable insights into the potential application of Fe–TiN heterostructures in solid-state cooling technologies, highlighting their enhanced magnetocaloric properties.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45668891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-19DOI: 10.3390/magnetochemistry9070187
Natália Andrýsková, P. Sourivong, M. Babincová, P. Babinec, M. Šimaljaková
Dithranol is one of the oldest and most efficient drugs used in the treatment of psoriasis. One of the challenges with using dithranol is its photostability, because it easily degrades when exposed to light. This study investigated the potential of coaxial core-sheath PCL/PVA nanofibers as a dual-functional system for enhancing dithranol photostability and remote-controlled drug delivery for psoriasis therapy. We have shown that coaxial nanofibers with titanium oxide nanoparticles (reflecting and absorbing ultra-violet light) in the PVA-based sheath part of the nanofibers can increase dithranol photostability. Incorporation of dithranol and magnetic nanoparticles into a PCL-based core of the nanofibers enables dithranol release control via an external radio-frequency field. The application of a radio-frequency field generates heat that can be used to control the release rate of drugs. Our approach therefore offers a non-invasive and remotely controlled drug release system that hold promise for the development of new topical formulations for psoriasis treatment using dithranol.
{"title":"Electrospun PCL/PVA Coaxial Nanofibers with Embedded Titanium Dioxide and Magnetic Nanoparticles for Stabilization and Controlled Release of Dithranol for Therapy of Psoriasis","authors":"Natália Andrýsková, P. Sourivong, M. Babincová, P. Babinec, M. Šimaljaková","doi":"10.3390/magnetochemistry9070187","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070187","url":null,"abstract":"Dithranol is one of the oldest and most efficient drugs used in the treatment of psoriasis. One of the challenges with using dithranol is its photostability, because it easily degrades when exposed to light. This study investigated the potential of coaxial core-sheath PCL/PVA nanofibers as a dual-functional system for enhancing dithranol photostability and remote-controlled drug delivery for psoriasis therapy. We have shown that coaxial nanofibers with titanium oxide nanoparticles (reflecting and absorbing ultra-violet light) in the PVA-based sheath part of the nanofibers can increase dithranol photostability. Incorporation of dithranol and magnetic nanoparticles into a PCL-based core of the nanofibers enables dithranol release control via an external radio-frequency field. The application of a radio-frequency field generates heat that can be used to control the release rate of drugs. Our approach therefore offers a non-invasive and remotely controlled drug release system that hold promise for the development of new topical formulations for psoriasis treatment using dithranol.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41672188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-18DOI: 10.3390/magnetochemistry9070186
P. Varlamov, A. Semisalova, Anh Dung Nguyen, M. Farle, Y. Laplace, M. Raynaud, O. Noel, P. Vavassori, V. Temnov
In this study, we present a novel investigation into the magnetic and morphological properties of equiatomic B2-ordered FeRh thin films irradiated with single high-intensity ultrashort laser pulses. The goal is to elucidate the effect of femtosecond laser ablation on the magnetic properties of FeRh. We employed Scanning Magneto-Optical Kerr Effect (S-MOKE) microscopy to examine the magnetic phase after laser processing, providing high spatial resolution and sensitivity. Our results for the first time demonstrated the appearance of a magneto-optical signal from the bottom of ablation craters, suggesting a transition from antiferromagnetic to ferromagnetic behavior. Fluence-resolved measurements clearly demonstrate that the ablation threshold coincides with the threshold of the antiferromagnet-to-ferromagnet phase transition. The existence of such a magnetic phase transition was independently confirmed by temperature-dependent S-MOKE measurements using a CW laser as a localized heat source. Whereas the initial FeRh film displayed a reversible antiferromagnet-ferromagnet phase transition, the laser-ablated structures exhibited irreversible changes in their magnetic properties. This comprehensive analysis revealed the strong correlation between the femtosecond laser ablation process and the magnetic phase transformation in FeRh thin films.
{"title":"Femtosecond Laser Ablation-Induced Magnetic Phase Transformations in FeRh Thin Films","authors":"P. Varlamov, A. Semisalova, Anh Dung Nguyen, M. Farle, Y. Laplace, M. Raynaud, O. Noel, P. Vavassori, V. Temnov","doi":"10.3390/magnetochemistry9070186","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070186","url":null,"abstract":"In this study, we present a novel investigation into the magnetic and morphological properties of equiatomic B2-ordered FeRh thin films irradiated with single high-intensity ultrashort laser pulses. The goal is to elucidate the effect of femtosecond laser ablation on the magnetic properties of FeRh. We employed Scanning Magneto-Optical Kerr Effect (S-MOKE) microscopy to examine the magnetic phase after laser processing, providing high spatial resolution and sensitivity. Our results for the first time demonstrated the appearance of a magneto-optical signal from the bottom of ablation craters, suggesting a transition from antiferromagnetic to ferromagnetic behavior. Fluence-resolved measurements clearly demonstrate that the ablation threshold coincides with the threshold of the antiferromagnet-to-ferromagnet phase transition. The existence of such a magnetic phase transition was independently confirmed by temperature-dependent S-MOKE measurements using a CW laser as a localized heat source. Whereas the initial FeRh film displayed a reversible antiferromagnet-ferromagnet phase transition, the laser-ablated structures exhibited irreversible changes in their magnetic properties. This comprehensive analysis revealed the strong correlation between the femtosecond laser ablation process and the magnetic phase transformation in FeRh thin films.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44066209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-17DOI: 10.3390/magnetochemistry9070185
Evgeniy D. Chernov, A. Lukoyanov
In this theoretical study, we investigate the effect of electron correlations on the electronic structure and magnetic properties of the full Heusler alloy Mn2NiAl in the framework of first-principles calculations. We investigate the electron correlation effect as employed within hybrid functional (HSE) and also within the DFT+U method with varied values of parameters between 0.9 and 6 eV. The XA-crystal structure was investigated with antiferromagnetic orderings of the magnetic moments of the manganese. It was found that with a growth of the Coulomb interaction parameter, the manganese ions magnetic moment increases, and it reaches the value of 4.15–4.46 μB per Mn. In addition, the total magnetic moment decreases because of the AFM ordering of the Mn ions and a small magnetic moment of Ni. The calculated total magnetic value agrees well with recent experiments demonstrating a low value of magnetization. This experimental value is most closely reproduced for the moderate values of the Coulomb parameter, also calculated in constrained LDA, while previous DFT studies substantially overestimated this value. It is also worth noticing that for all values of the Coulomb interaction parameter, this compound remains metallic in its electronic structure in agreement with transport measurements.
{"title":"Effect of Electron Correlations on the Electronic Structure and Magnetic Properties of the Full Heusler Alloy Mn2NiAl","authors":"Evgeniy D. Chernov, A. Lukoyanov","doi":"10.3390/magnetochemistry9070185","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070185","url":null,"abstract":"In this theoretical study, we investigate the effect of electron correlations on the electronic structure and magnetic properties of the full Heusler alloy Mn2NiAl in the framework of first-principles calculations. We investigate the electron correlation effect as employed within hybrid functional (HSE) and also within the DFT+U method with varied values of parameters between 0.9 and 6 eV. The XA-crystal structure was investigated with antiferromagnetic orderings of the magnetic moments of the manganese. It was found that with a growth of the Coulomb interaction parameter, the manganese ions magnetic moment increases, and it reaches the value of 4.15–4.46 μB per Mn. In addition, the total magnetic moment decreases because of the AFM ordering of the Mn ions and a small magnetic moment of Ni. The calculated total magnetic value agrees well with recent experiments demonstrating a low value of magnetization. This experimental value is most closely reproduced for the moderate values of the Coulomb parameter, also calculated in constrained LDA, while previous DFT studies substantially overestimated this value. It is also worth noticing that for all values of the Coulomb interaction parameter, this compound remains metallic in its electronic structure in agreement with transport measurements.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49320197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-17DOI: 10.3390/magnetochemistry9070184
Tudor-Gabriel Mocioi, Antonia Ghita, V. Temnov
Using valid experimental parameters, we quantify the magnitude of resonantly phonon-driven precession of exchange magnons in freestanding ferromagnetic nickel thin films on their thickness L. Analytical solutions of acoustically driven equations for magnon oscillators display a nonmonotonous dependence of the peak magnetization precession on the film thickness. It is explained by different L-dependence of multiple prefactors entering in the expression for the total magnetization dynamics. Depending on the ratio of acoustic and magnetic (Gilbert) damping constants, the magnetization precession is shown to be amplified by a Q-factor of either the phonon or the magnon resonance. The increase in the phonon mode amplitude for thinner membranes is also found to be significant. Focusing on the magnetization dynamics excited by the two first acoustic eigenmodes with p=1 and p=2, we predict the optimum thicknesses of nickel membranes to achieve large amplitude magnetization precession at multi 100 GHz frequencies at reasonably low values of an external magnetic field. By extending the study to the case of Ni-Si bilayers, we show that these resonances are achievable at even higher frequencies, approaching the THz range.
{"title":"Towards Resonantly Enhanced Acoustic Phonon-Exchange Magnon Interactions at THz Frequencies","authors":"Tudor-Gabriel Mocioi, Antonia Ghita, V. Temnov","doi":"10.3390/magnetochemistry9070184","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070184","url":null,"abstract":"Using valid experimental parameters, we quantify the magnitude of resonantly phonon-driven precession of exchange magnons in freestanding ferromagnetic nickel thin films on their thickness L. Analytical solutions of acoustically driven equations for magnon oscillators display a nonmonotonous dependence of the peak magnetization precession on the film thickness. It is explained by different L-dependence of multiple prefactors entering in the expression for the total magnetization dynamics. Depending on the ratio of acoustic and magnetic (Gilbert) damping constants, the magnetization precession is shown to be amplified by a Q-factor of either the phonon or the magnon resonance. The increase in the phonon mode amplitude for thinner membranes is also found to be significant. Focusing on the magnetization dynamics excited by the two first acoustic eigenmodes with p=1 and p=2, we predict the optimum thicknesses of nickel membranes to achieve large amplitude magnetization precession at multi 100 GHz frequencies at reasonably low values of an external magnetic field. By extending the study to the case of Ni-Si bilayers, we show that these resonances are achievable at even higher frequencies, approaching the THz range.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46225585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-15DOI: 10.3390/magnetochemistry9070183
M. Segantini, Gianluca Marcozzi, D. Djekic, Anh Chu, D. Amkreutz, C. T. Trinh, Sebastian Neubert, B. Stannowski, K. Jacob, I. Rudolph, Joseph E. McPeak, J. Anders, B. Naydenov, K. Lips
Electrically detected magnetic resonance (EDMR) is a spectroscopic technique that provides information about the physical properties of materials through the detection of variations in conductivity induced by spin-dependent processes. EDMR has been widely applied to investigate thin-film semiconductor materials in which the presence of defects can induce the current limiting processes. Conventional EDMR measurements are performed on samples with a special geometry that allows the use of a typical electron paramagnetic resonance (EPR) resonator. For such measurements, it is of utmost importance that the geometry of the sample under assessment does not influence the results of the experiment. Here, we present a single-board EPR spectrometer using a chip-integrated, voltage-controlled oscillator (VCO) array as a planar microwave source, whose geometry optimally matches that of a standard EDMR sample, and which greatly facilitates electrical interfacing to the device under assessment. The probehead combined an ultrasensitive transimpedance amplifier (TIA) with a twelve-coil array, VCO-based, single-board EPR spectrometer to permit EDMR-on-a-Chip (EDMRoC) investigations. EDMRoC measurements were performed at room temperature on a thin-film hydrogenated amorphous silicon (a-Si:H) pin solar cell under dark and forward bias conditions, and the recombination current driven by the a-Si:H dangling bonds (db) was detected. These experiments serve as a proof of concept for a new generation of small and versatile spectrometers that allow in situ and operando EDMR experiments.
{"title":"Electrically Detected Magnetic Resonance on a Chip (EDMRoC) for Analysis of Thin-Film Silicon Photovoltaics","authors":"M. Segantini, Gianluca Marcozzi, D. Djekic, Anh Chu, D. Amkreutz, C. T. Trinh, Sebastian Neubert, B. Stannowski, K. Jacob, I. Rudolph, Joseph E. McPeak, J. Anders, B. Naydenov, K. Lips","doi":"10.3390/magnetochemistry9070183","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070183","url":null,"abstract":"Electrically detected magnetic resonance (EDMR) is a spectroscopic technique that provides information about the physical properties of materials through the detection of variations in conductivity induced by spin-dependent processes. EDMR has been widely applied to investigate thin-film semiconductor materials in which the presence of defects can induce the current limiting processes. Conventional EDMR measurements are performed on samples with a special geometry that allows the use of a typical electron paramagnetic resonance (EPR) resonator. For such measurements, it is of utmost importance that the geometry of the sample under assessment does not influence the results of the experiment. Here, we present a single-board EPR spectrometer using a chip-integrated, voltage-controlled oscillator (VCO) array as a planar microwave source, whose geometry optimally matches that of a standard EDMR sample, and which greatly facilitates electrical interfacing to the device under assessment. The probehead combined an ultrasensitive transimpedance amplifier (TIA) with a twelve-coil array, VCO-based, single-board EPR spectrometer to permit EDMR-on-a-Chip (EDMRoC) investigations. EDMRoC measurements were performed at room temperature on a thin-film hydrogenated amorphous silicon (a-Si:H) pin solar cell under dark and forward bias conditions, and the recombination current driven by the a-Si:H dangling bonds (db) was detected. These experiments serve as a proof of concept for a new generation of small and versatile spectrometers that allow in situ and operando EDMR experiments.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42158473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-12DOI: 10.3390/magnetochemistry9070182
José F. Malta, M. Henriques, J. A. Paixão, A. P. Gonçalves
GaMo4Se8, is a lacunar spinel where skyrmions have been recently reported. This compound belongs to the GaM4X8 family, where M is a transition metal (V or Mo) and X is a chalcogenide (S or Se). In this work, we have obtained pure GaMo4Se8 in polycrystalline form through an innovative two-step synthetic route. Phase purity and chemical composition were confirmed through the Rietveld refinement of the powder XRD pattern, the sample characterisation having been complemented with SEM analysis. The magnetic phase diagram was investigated using DC (VSM) and AC magnetometry, which disclosed the presence of cycloidal, skyrmionic and ferromagnetic phases in polycrystalline GaMo4Se8.
{"title":"Synthesis and Structural and Magnetic Properties of Polycrystalline GaMo4Se8","authors":"José F. Malta, M. Henriques, J. A. Paixão, A. P. Gonçalves","doi":"10.3390/magnetochemistry9070182","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070182","url":null,"abstract":"GaMo4Se8, is a lacunar spinel where skyrmions have been recently reported. This compound belongs to the GaM4X8 family, where M is a transition metal (V or Mo) and X is a chalcogenide (S or Se). In this work, we have obtained pure GaMo4Se8 in polycrystalline form through an innovative two-step synthetic route. Phase purity and chemical composition were confirmed through the Rietveld refinement of the powder XRD pattern, the sample characterisation having been complemented with SEM analysis. The magnetic phase diagram was investigated using DC (VSM) and AC magnetometry, which disclosed the presence of cycloidal, skyrmionic and ferromagnetic phases in polycrystalline GaMo4Se8.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46575085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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