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":" ","pages":""},"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":" ","pages":""},"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":" ","pages":""},"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":" ","pages":""},"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":" ","pages":""},"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":" ","pages":""},"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":" ","pages":""},"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}
Pub Date : 2023-07-11DOI: 10.3390/magnetochemistry9070180
Hiroyuki Tajima, Takeshi Oda, Tomofumi Kadoya
This paper presents the concept and experimental evidence for the nonthermal equilibrium (NTE) process of charge carrier extraction in metal/insulator/organic semiconductor/metal (MIOM) capacitors. These capacitors are structurally similar to metal/insulator/semiconductor/(metal) (MIS) capacitors found in standard semiconductor textbooks. The difference between the two capacitors is that the (organic) semiconductor/metal contacts in the MIOM capacitors are of the Schottky type, whereas the contacts in the MIS capacitors are of the ohmic type. Moreover, the mobilities of most organic semiconductors are significantly lower than those of inorganic semiconductors. As the MIOM structure is identical to the electrode portion of an organic field-effect transistor (OFET) with top-contact and bottom-gate electrodes, the hysteretic behavior of the OFET transfer characteristics can be deduced from the NTE phenomenon observed in MIOM capacitors.
{"title":"Nonthermal Equilibrium Process of Charge Carrier Extraction in Metal/Insulator/Organic Semiconductor/Metal (MIOM) Junction","authors":"Hiroyuki Tajima, Takeshi Oda, Tomofumi Kadoya","doi":"10.3390/magnetochemistry9070180","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070180","url":null,"abstract":"This paper presents the concept and experimental evidence for the nonthermal equilibrium (NTE) process of charge carrier extraction in metal/insulator/organic semiconductor/metal (MIOM) capacitors. These capacitors are structurally similar to metal/insulator/semiconductor/(metal) (MIS) capacitors found in standard semiconductor textbooks. The difference between the two capacitors is that the (organic) semiconductor/metal contacts in the MIOM capacitors are of the Schottky type, whereas the contacts in the MIS capacitors are of the ohmic type. Moreover, the mobilities of most organic semiconductors are significantly lower than those of inorganic semiconductors. As the MIOM structure is identical to the electrode portion of an organic field-effect transistor (OFET) with top-contact and bottom-gate electrodes, the hysteretic behavior of the OFET transfer characteristics can be deduced from the NTE phenomenon observed in MIOM capacitors.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44419561","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 : 2023-07-11DOI: 10.3390/magnetochemistry9070181
Xiaogang Yu, Renpeng Yang, Chengwei Wu, Boqi Liu, W. Zhang
Zn0.6Mg0.4CrxFe2−xO4 (0 ≤ x ≤ 0.4) nanoparticles were synthesized using a hydrothermal technique. The obtained magnetic nanoparticles (MNPs) exhibited a spinel structure, where the lattice constant decreased with the Cr3+ ion content. The doping of Cr3+ ion (x = 0.1) increased the specific saturation magnetization to 46.4 emu/g but decreased to 20.0 emu/g with the further increase in the Cr3+ ion content to x = 0.4. The decrement in Curie temperature was ascribed to the weakened super-exchange interaction between the metal ions located at A-sites and B-sites, which arose from the doping of the Cr3+ ion. The T2-weighted images gradually darkened with the increase in Zn0.6Mg0.4Cr0.1Fe1.9O4 nanoparticles concentration, suggesting that the nanoparticles can enhance the image contrast. Zn0.6Mg0.4CrxFe2−xO4 (0 ≤ x ≤ 0.4) nanoparticles were able to heat the agar phantom to the hyperthermia temperature under the safe alternating magnetic field, which showed their potential in the magnetic induction hyperthermia.
{"title":"Effect of Cr3+ Doping on Magnetic Properties of Zn-Mg Ferrite Nanoparticles","authors":"Xiaogang Yu, Renpeng Yang, Chengwei Wu, Boqi Liu, W. Zhang","doi":"10.3390/magnetochemistry9070181","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070181","url":null,"abstract":"Zn0.6Mg0.4CrxFe2−xO4 (0 ≤ x ≤ 0.4) nanoparticles were synthesized using a hydrothermal technique. The obtained magnetic nanoparticles (MNPs) exhibited a spinel structure, where the lattice constant decreased with the Cr3+ ion content. The doping of Cr3+ ion (x = 0.1) increased the specific saturation magnetization to 46.4 emu/g but decreased to 20.0 emu/g with the further increase in the Cr3+ ion content to x = 0.4. The decrement in Curie temperature was ascribed to the weakened super-exchange interaction between the metal ions located at A-sites and B-sites, which arose from the doping of the Cr3+ ion. The T2-weighted images gradually darkened with the increase in Zn0.6Mg0.4Cr0.1Fe1.9O4 nanoparticles concentration, suggesting that the nanoparticles can enhance the image contrast. Zn0.6Mg0.4CrxFe2−xO4 (0 ≤ x ≤ 0.4) nanoparticles were able to heat the agar phantom to the hyperthermia temperature under the safe alternating magnetic field, which showed their potential in the magnetic induction hyperthermia.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48397865","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 : 2023-07-10DOI: 10.3390/magnetochemistry9070179
C. Favieres
The Special Issue Soft and Hard Magnetic Materials: Latest Advances and Prospects aims to provide researchers with an overview of some aspects of the current research in magnetic materials from theoretical studies to their applications, including their fabrication and characterization [...]
{"title":"Special Issue: Soft and Hard Magnetic Materials: Latest Advances and Prospects","authors":"C. Favieres","doi":"10.3390/magnetochemistry9070179","DOIUrl":"https://doi.org/10.3390/magnetochemistry9070179","url":null,"abstract":"The Special Issue Soft and Hard Magnetic Materials: Latest Advances and Prospects aims to provide researchers with an overview of some aspects of the current research in magnetic materials from theoretical studies to their applications, including their fabrication and characterization [...]","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48992239","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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