Pub Date : 2023-11-15DOI: 10.3390/magnetochemistry9110228
P. A. Chernavskiy, A. Novakova, G. V. Pankina, D. A. Pankratov, S. I. Panfilov, G. A. Petrovskaya
A new method for obtaining nanosized particles of iron oxides using porous silica gel is proposed. In situ magnetometry was used to study the reduction of hematite deposited on silica gel during the thermolysis of glucose. The formed magnetite and maghemite obtained by subsequent oxidation of the magnetite were studied using X-ray diffraction and Mossbauer spectroscopy. It was shown that both the size of the oxide particles and the phase composition significantly depended on the porous structure of the silica gel. In particular, the formation of superparamagnetic maghemite particles on silica gels with pore sizes of 30, 15 and 10 nm was demonstrated.
提出了一种利用多孔硅胶获得纳米级铁氧化物颗粒的新方法。利用原位磁强计研究了葡萄糖热解过程中沉积在硅胶上的赤铁矿的还原过程。使用 X 射线衍射和莫斯鲍尔光谱法研究了形成的磁铁矿和随后氧化磁铁矿得到的镁铁矿。结果表明，氧化物颗粒的大小和相组成在很大程度上取决于硅胶的多孔结构。特别是在孔径为 30、15 和 10 纳米的二氧化硅凝胶上形成了超顺磁性的磁铁矿颗粒。
{"title":"Synthesis and Characterization of Hematite, Magnetite and Maghemite Supported on Silica Gel","authors":"P. A. Chernavskiy, A. Novakova, G. V. Pankina, D. A. Pankratov, S. I. Panfilov, G. A. Petrovskaya","doi":"10.3390/magnetochemistry9110228","DOIUrl":"https://doi.org/10.3390/magnetochemistry9110228","url":null,"abstract":"A new method for obtaining nanosized particles of iron oxides using porous silica gel is proposed. In situ magnetometry was used to study the reduction of hematite deposited on silica gel during the thermolysis of glucose. The formed magnetite and maghemite obtained by subsequent oxidation of the magnetite were studied using X-ray diffraction and Mossbauer spectroscopy. It was shown that both the size of the oxide particles and the phase composition significantly depended on the porous structure of the silica gel. In particular, the formation of superparamagnetic maghemite particles on silica gels with pore sizes of 30, 15 and 10 nm was demonstrated.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":"25 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139271289","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 : 2023-11-15DOI: 10.3390/magnetochemistry9110227
E. Kalinina, Nataliya D. Kundikova, Dmitrii K. Kuznetsov, Maxim G. Ivanov
In this work, the possibility of fabricating composite magneto-optical ceramics by electrophoretic deposition (EPD) of nanopowders and high-temperature vacuum sintering of the compacts was investigated. Holmium oxide was chosen as a magneto-optical material for the study because of its transparency in the mid-IR range. Nanopowders of magneto-optical (Ho0.95La0.05)2O3 (HoLa) material were made by self-propagating high-temperature synthesis. Nanopowders of (Y0.9La0.1)2O3 (YLa) were made by laser synthesis for an inactive matrix. The process of formation of one- and two-layer compacts by EPD of the nanopowders from alcohol suspensions was studied in detail. Acetylacetone was shown to be a good dispersant to obtain alcohol suspensions of the nanopowders, characterized by high zeta potential values (+29–+80 mV), and to carry out a stable EPD process. One-layer compacts were made from the HoLa and YLa nanopowders with a density of 30–43%. It was found out that the introduction of polyvinyl butyral (PVB) into the suspension leads to a decrease in the mass and thickness of the green bodies deposited, but does not significantly affect their density. The possibility of making two-layer (YLa/HoLa) compacts with a thickness of up to 2.6 mm and a density of up to 46% was demonstrated. Sintering such compacts in a vacuum at a temperature of 1750 °C for 10 h leads to the formation of ceramics with a homogeneous boundary between the YLa/HoLa layers and a thickness of the interdiffused ion layer of about 30 μm.
{"title":"Electrophoretic Deposition of One- and Two-Layer Compacts of Holmium and Yttrium Oxide Nanopowders for Magneto-Optical Ceramics Fabrication","authors":"E. Kalinina, Nataliya D. Kundikova, Dmitrii K. Kuznetsov, Maxim G. Ivanov","doi":"10.3390/magnetochemistry9110227","DOIUrl":"https://doi.org/10.3390/magnetochemistry9110227","url":null,"abstract":"In this work, the possibility of fabricating composite magneto-optical ceramics by electrophoretic deposition (EPD) of nanopowders and high-temperature vacuum sintering of the compacts was investigated. Holmium oxide was chosen as a magneto-optical material for the study because of its transparency in the mid-IR range. Nanopowders of magneto-optical (Ho0.95La0.05)2O3 (HoLa) material were made by self-propagating high-temperature synthesis. Nanopowders of (Y0.9La0.1)2O3 (YLa) were made by laser synthesis for an inactive matrix. The process of formation of one- and two-layer compacts by EPD of the nanopowders from alcohol suspensions was studied in detail. Acetylacetone was shown to be a good dispersant to obtain alcohol suspensions of the nanopowders, characterized by high zeta potential values (+29–+80 mV), and to carry out a stable EPD process. One-layer compacts were made from the HoLa and YLa nanopowders with a density of 30–43%. It was found out that the introduction of polyvinyl butyral (PVB) into the suspension leads to a decrease in the mass and thickness of the green bodies deposited, but does not significantly affect their density. The possibility of making two-layer (YLa/HoLa) compacts with a thickness of up to 2.6 mm and a density of up to 46% was demonstrated. Sintering such compacts in a vacuum at a temperature of 1750 °C for 10 h leads to the formation of ceramics with a homogeneous boundary between the YLa/HoLa layers and a thickness of the interdiffused ion layer of about 30 μm.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":"4 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139272769","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 : 2023-11-06DOI: 10.3390/magnetochemistry9110226
Roman Boča, Cyril Rajnák, Ján Titiš
The involvement of spin symmetry in the evaluation of zero-field energy levels in polynuclear transition metal and lanthanide complexes facilitates the division of the large-scale Hamiltonian matrix referring to isotropic exchange. This method is based on the use of an irreducible tensor approach. This allows for the fitting of the experimental data of magnetic susceptibility and magnetization in a reasonable time for relatively large clusters for any coupling path. Several examples represented by catena-[AN} and cyclo-[AN] systems were modeled. Magnetic data for 20 actually existing endohedral clusters were analyzed and interpreted.
{"title":"Spin Symmetry in Polynuclear Exchange-Coupled Clusters","authors":"Roman Boča, Cyril Rajnák, Ján Titiš","doi":"10.3390/magnetochemistry9110226","DOIUrl":"https://doi.org/10.3390/magnetochemistry9110226","url":null,"abstract":"The involvement of spin symmetry in the evaluation of zero-field energy levels in polynuclear transition metal and lanthanide complexes facilitates the division of the large-scale Hamiltonian matrix referring to isotropic exchange. This method is based on the use of an irreducible tensor approach. This allows for the fitting of the experimental data of magnetic susceptibility and magnetization in a reasonable time for relatively large clusters for any coupling path. Several examples represented by catena-[AN} and cyclo-[AN] systems were modeled. Magnetic data for 20 actually existing endohedral clusters were analyzed and interpreted.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":"22 S4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135589573","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 : 2023-11-03DOI: 10.3390/magnetochemistry9110225
Masato Fukuda, Ken Eguchi, Kazuma Matsumoto, Ko Yoneda, Yasunori Yamada, Haruka Yoshino, Yuki Imamura, Naoya Yamamoto, Masaaki Ohba, Masayuki Koikawa
A mononuclear Ni(II) complex, [Ni(HL1)2], (1) and a novel tetranuclear heterometal Mn-Ni complex, [Mn3Ni(L1)4Cl2(EtOH)2], (2) [H2L1 = N-(2-hydroxymethylphenyl)salicylideneimine], have been synthesized and characterized via X-ray crystal structure analyses, infrared spectra, and elemental analyses. The structure analyses revealed that the tridentate ligand, H2L1, coordinates in a facial mode for Ni and a mer mode for Mn, respectively. Complex 2 includes Mn(II)Mn(III)2Ni(II) tetranuclear metal core bridged by μ-phenoxo and μ-alkoxo oxygens. Magnetic measurements for 2 indicate that weak ferromagnetic interactions (JMn(III)Ni(II) = 2.23, JMn(III)Mn(II) = 0.46, JMn(II)Ni(II) = 1.78, and JMn(III)Mn(III) = 0.58 cm−1) dominate in the tetranuclear core. Additionally, in alternating current (AC) magnetic measurements, frequency-dependent out-of-phase responses were observed.
{"title":"Novel Tetranuclear Heterometallic Mn3Ni and Mononuclear Ni Complexes with an ONO Schiff Base Ligand: Synthesis, Crystal Structures, and Magnetic Properties","authors":"Masato Fukuda, Ken Eguchi, Kazuma Matsumoto, Ko Yoneda, Yasunori Yamada, Haruka Yoshino, Yuki Imamura, Naoya Yamamoto, Masaaki Ohba, Masayuki Koikawa","doi":"10.3390/magnetochemistry9110225","DOIUrl":"https://doi.org/10.3390/magnetochemistry9110225","url":null,"abstract":"A mononuclear Ni(II) complex, [Ni(HL1)2], (1) and a novel tetranuclear heterometal Mn-Ni complex, [Mn3Ni(L1)4Cl2(EtOH)2], (2) [H2L1 = N-(2-hydroxymethylphenyl)salicylideneimine], have been synthesized and characterized via X-ray crystal structure analyses, infrared spectra, and elemental analyses. The structure analyses revealed that the tridentate ligand, H2L1, coordinates in a facial mode for Ni and a mer mode for Mn, respectively. Complex 2 includes Mn(II)Mn(III)2Ni(II) tetranuclear metal core bridged by μ-phenoxo and μ-alkoxo oxygens. Magnetic measurements for 2 indicate that weak ferromagnetic interactions (JMn(III)Ni(II) = 2.23, JMn(III)Mn(II) = 0.46, JMn(II)Ni(II) = 1.78, and JMn(III)Mn(III) = 0.58 cm−1) dominate in the tetranuclear core. Additionally, in alternating current (AC) magnetic measurements, frequency-dependent out-of-phase responses were observed.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":"14 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135820414","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 : 2023-11-02DOI: 10.3390/magnetochemistry9110224
Alexander Moskvin
A wide class of materials with different crystal and electronic structures including quasi-2D unconventional superconductors, such as cuprates, nickelates, ferropnictides/chalcogenides, ruthenate Sr2RuO4, and 3D systems, such as manganites RMnO3, ferrates (CaSr)FeO3, nickelates RNiO3, silver oxide AgO, are based on Jahn–Teller 3d and 4d ions. These unusual materials, called Jahn–Teller (JT) magnets, are characterized by an extremely rich variety of phase states, spanning from non-magnetic and magnetic insulators to unusual metallic and superconducting states. The unconventional properties of JT magnets can be attributed to the instability of their highly symmetric Jahn–Teller “progenitors” with the ground orbital E-state with repect to charge transfer, anti-Jahn–Teller d-d disproportionation, and the formation of a system of effective local composite spin–singlet or spin–triplet, electronic, or hole S-type bosons moving in a non-magnetic or magnetic lattice. We consider specific features of the anti-JT-disproportionation reaction, properties of the electron–hole dimers, possible phase states and effective Hamiltonians for single- and two-band JT magnets, concluding with a short overview of physical properties for actual JT magnets.
{"title":"Jahn–Teller Magnets","authors":"Alexander Moskvin","doi":"10.3390/magnetochemistry9110224","DOIUrl":"https://doi.org/10.3390/magnetochemistry9110224","url":null,"abstract":"A wide class of materials with different crystal and electronic structures including quasi-2D unconventional superconductors, such as cuprates, nickelates, ferropnictides/chalcogenides, ruthenate Sr2RuO4, and 3D systems, such as manganites RMnO3, ferrates (CaSr)FeO3, nickelates RNiO3, silver oxide AgO, are based on Jahn–Teller 3d and 4d ions. These unusual materials, called Jahn–Teller (JT) magnets, are characterized by an extremely rich variety of phase states, spanning from non-magnetic and magnetic insulators to unusual metallic and superconducting states. The unconventional properties of JT magnets can be attributed to the instability of their highly symmetric Jahn–Teller “progenitors” with the ground orbital E-state with repect to charge transfer, anti-Jahn–Teller d-d disproportionation, and the formation of a system of effective local composite spin–singlet or spin–triplet, electronic, or hole S-type bosons moving in a non-magnetic or magnetic lattice. We consider specific features of the anti-JT-disproportionation reaction, properties of the electron–hole dimers, possible phase states and effective Hamiltonians for single- and two-band JT magnets, concluding with a short overview of physical properties for actual JT magnets.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135935301","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 : 2023-10-29DOI: 10.3390/magnetochemistry9110223
M. Zaid Zaz, Thilini K. Ekanayaka, Ruihua Cheng, Peter A. Dowben
Here, we examine the conductance changes associated with the change in spin state in a variety of different structures, using the example of the spin crossover complex [Fe(H2B(pz)2)2(bipy)] (pz = (pyrazol-1-yl)-borate and bipy = 2,2′-bipyridine) and [Fe(Htrz)2(trz)](BF4)] (Htrz = 1H-1,2,4-triazole) thin films. This conductance change is highly variable depending on the mechanism driving the change in spin state, the substrate, and the device geometry. Simply stated, the choice of spin crossover complex used to build a device is not the only factor in determining the change in conductance with the change in spin state.
{"title":"Variability of the Conductance Changes Associated with the Change in the Spin State in Molecular Spin Crossover Complexes","authors":"M. Zaid Zaz, Thilini K. Ekanayaka, Ruihua Cheng, Peter A. Dowben","doi":"10.3390/magnetochemistry9110223","DOIUrl":"https://doi.org/10.3390/magnetochemistry9110223","url":null,"abstract":"Here, we examine the conductance changes associated with the change in spin state in a variety of different structures, using the example of the spin crossover complex [Fe(H2B(pz)2)2(bipy)] (pz = (pyrazol-1-yl)-borate and bipy = 2,2′-bipyridine) and [Fe(Htrz)2(trz)](BF4)] (Htrz = 1H-1,2,4-triazole) thin films. This conductance change is highly variable depending on the mechanism driving the change in spin state, the substrate, and the device geometry. Simply stated, the choice of spin crossover complex used to build a device is not the only factor in determining the change in conductance with the change in spin state.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":"142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136157984","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 : 2023-10-20DOI: 10.3390/magnetochemistry9100222
Valentina Zhukova, Alfonso García-Gómez, Alvaro Gonzalez, Margarita Churyukanova, Sergey Kaloshkin, Paula Corte-Leon, Mihail Ipatov, Jesus Olivera, Arcady Zhukov
We studied the magnetostriction coefficients, λs, Curie temperature, Tc, and their dependence on annealing conditions in Fe47Ni27Si11B13C2 and Co67Fe3.9Ni1.5B11.5Si14.5Mo1.6 amorphous glass-coated microwires with rather different character of hysteresis loops. A positive λs ≈ 20 × 10−6 is observed in as-prepared Fe47Ni27Si11B13C2, while low and negative λs ≈ −0.3 × 10−6 is obtained for Co67Fe3.9Ni1.5B11.5Si14.5Mo1.6 microwire. Annealing affects the magnetostriction coefficients and Curie temperatures, Tc, of both Fe47Ni27Si11B13C2 and Co67Fe3.9Ni1.5B11.5Si14.5Mo1.6 glass-coated microwires in a similar way. Observed dependencies of hysteresis loops, λs and Tc on annealing conditions are discussed in terms of superposition of internal stresses relaxation and structural relaxation of studied microwires. We observed linear λs dependence on applied stress, σ, in both studied microwires. A decrease in the magnetostriction coefficient upon applied stress is observed for Co-rich microwires with low and negative magnetostriction coefficient. On the contrary, for Fe-Ni-rich microwires with a positive magnetostriction coefficient, an increase in the magnetostriction coefficient with applied stress is observed. The observed results are discussed considering the internal stresses relaxation and short range atomic rearrangements induced by annealing on hysteresis loops, magnetostriction coefficients and Curie temperatures of studied microwires.
{"title":"The Magnetostriction of Amorphous Magnetic Microwires: The Role of the Local Atomic Environment and Internal Stresses Relaxation","authors":"Valentina Zhukova, Alfonso García-Gómez, Alvaro Gonzalez, Margarita Churyukanova, Sergey Kaloshkin, Paula Corte-Leon, Mihail Ipatov, Jesus Olivera, Arcady Zhukov","doi":"10.3390/magnetochemistry9100222","DOIUrl":"https://doi.org/10.3390/magnetochemistry9100222","url":null,"abstract":"We studied the magnetostriction coefficients, λs, Curie temperature, Tc, and their dependence on annealing conditions in Fe47Ni27Si11B13C2 and Co67Fe3.9Ni1.5B11.5Si14.5Mo1.6 amorphous glass-coated microwires with rather different character of hysteresis loops. A positive λs ≈ 20 × 10−6 is observed in as-prepared Fe47Ni27Si11B13C2, while low and negative λs ≈ −0.3 × 10−6 is obtained for Co67Fe3.9Ni1.5B11.5Si14.5Mo1.6 microwire. Annealing affects the magnetostriction coefficients and Curie temperatures, Tc, of both Fe47Ni27Si11B13C2 and Co67Fe3.9Ni1.5B11.5Si14.5Mo1.6 glass-coated microwires in a similar way. Observed dependencies of hysteresis loops, λs and Tc on annealing conditions are discussed in terms of superposition of internal stresses relaxation and structural relaxation of studied microwires. We observed linear λs dependence on applied stress, σ, in both studied microwires. A decrease in the magnetostriction coefficient upon applied stress is observed for Co-rich microwires with low and negative magnetostriction coefficient. On the contrary, for Fe-Ni-rich microwires with a positive magnetostriction coefficient, an increase in the magnetostriction coefficient with applied stress is observed. The observed results are discussed considering the internal stresses relaxation and short range atomic rearrangements induced by annealing on hysteresis loops, magnetostriction coefficients and Curie temperatures of studied microwires.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135617427","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 : 2023-10-18DOI: 10.3390/magnetochemistry9100221
Eisuke Chikayama, Stephan J. Ginthör, Matthias Bechmann, Norbert Müller
Radio amplification using stimulated emission of radiation (RASER) effects in the NMR can increase NMR signals over time due to a feedback loop between the sample magnetization and the probe coil coupled with radiation damping (RD). Previously, RD rates had been directly observed only for the 1H, 3He, 17O and 129Xe nuclei. We report that experimental direct measurements of an NMR RASER to determine RD time constants for the three heteronuclei (133Cs (I = 7/2), 7Li (I = 3/2) and 31P (I = 1/2)) in a highly concentrated solution from the NMR RASER emissions using a conventional NMR probe. Under conditions where the RD rate exceeds the transverse relaxation rate (i.e., the NMR RASER condition is fulfilled), we recorded both the transverse NMR RASER response to imperfect inversion and the recovery of longitudinal magnetization. The data were directly evaluated based on the well-known Bloom model as estimated RD rate constants of 8.0, 1.8 and 25 Hz for 133Cs, 7Li and 31P, respectively. The proposed method can be applied to observe RD rate constants for the other nuclei as well.
在核磁共振中使用受激辐射(激光)效应的无线电放大可以随着时间的推移增加核磁共振信号，这是由于样品磁化和探针线圈之间的反馈回路加上辐射阻尼(RD)。在此之前，只直接观察到1H、3He、17O和129Xe原子核的RD速率。我们报告了用传统的核磁共振探针从核磁共振激光发射中测定高浓度溶液中三种异核(133Cs (I = 7/2)， 7Li (I = 3/2)和31P (I = 1/2)的RD时间常数的实验直接测量。在RD速率超过横向弛豫速率的条件下(即满足NMR RASER条件)，我们记录了横向NMR RASER对不完全反演的响应和纵向磁化的恢复。根据著名的Bloom模型对数据进行直接评估，估计133c、7Li和31P的RD速率常数分别为8.0、1.8和25 Hz。所提出的方法也可以应用于其他原子核的RD速率常数的观测。
{"title":"Estimation of Radiation Damping Rates Using 133Cs, 7Li and 31P Solution NMR Spectroscopy and a Theoretical NMR RASER Model","authors":"Eisuke Chikayama, Stephan J. Ginthör, Matthias Bechmann, Norbert Müller","doi":"10.3390/magnetochemistry9100221","DOIUrl":"https://doi.org/10.3390/magnetochemistry9100221","url":null,"abstract":"Radio amplification using stimulated emission of radiation (RASER) effects in the NMR can increase NMR signals over time due to a feedback loop between the sample magnetization and the probe coil coupled with radiation damping (RD). Previously, RD rates had been directly observed only for the 1H, 3He, 17O and 129Xe nuclei. We report that experimental direct measurements of an NMR RASER to determine RD time constants for the three heteronuclei (133Cs (I = 7/2), 7Li (I = 3/2) and 31P (I = 1/2)) in a highly concentrated solution from the NMR RASER emissions using a conventional NMR probe. Under conditions where the RD rate exceeds the transverse relaxation rate (i.e., the NMR RASER condition is fulfilled), we recorded both the transverse NMR RASER response to imperfect inversion and the recovery of longitudinal magnetization. The data were directly evaluated based on the well-known Bloom model as estimated RD rate constants of 8.0, 1.8 and 25 Hz for 133Cs, 7Li and 31P, respectively. The proposed method can be applied to observe RD rate constants for the other nuclei as well.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135887947","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 : 2023-10-08DOI: 10.3390/magnetochemistry9100218
Irina O. Dzhun, Andrey V. Gerasimenko, Alexander A. Ezhov, Stanislav I. Bezzubov, Valeria V. Rodionova, Christina A. Gritsenko, Nikolai G. Chechenin
Thin film ferromagnet/antiferromagnet (F/AF) exchange biased structures that are widely used in GMR spin valves are considered nowadays as promising systems for antiferromagnetic spintronic and spin-orbitronic devices. Here, the temperature dependences of magnetization dynamics in Co/IrMn and Co/FeMn F/AF structures are investigated using ferromagnetic resonance (FMR) in comparison to a free Co layer. A strong additional decrease in the resonance field was observed in Co/IrMn with a temperature decrease attributed to the rotatable anisotropy increase, which almost vanished at room temperature. In contrast to Co/IrMn, the contribution of the rotatable anisotropy in Co/FeMn is much weaker, even though it exists at RT, it is negative, and slightly varies with the temperature and resonance field shift in Co/FeMn. This is mainly due to unidirectional exchange anisotropy. FMR linewidth for the free Co layer increases with decreasing temperature and is accompanied with a slow relaxation process, while the additional contribution to FMR line broadening in Co/IrMn and Co/FeMn structures is correlated with variation in the exchange anisotropy. The observed results are discussed based on structural and surface morphology and magnetization reversal characterization using X-ray diffraction, atomic force microscopy, and vibrating sample magnetometry data.
{"title":"Temperature Dependence of Magnetization Dynamics in Co/IrMn and Co/FeMn Exchange Biased Structures","authors":"Irina O. Dzhun, Andrey V. Gerasimenko, Alexander A. Ezhov, Stanislav I. Bezzubov, Valeria V. Rodionova, Christina A. Gritsenko, Nikolai G. Chechenin","doi":"10.3390/magnetochemistry9100218","DOIUrl":"https://doi.org/10.3390/magnetochemistry9100218","url":null,"abstract":"Thin film ferromagnet/antiferromagnet (F/AF) exchange biased structures that are widely used in GMR spin valves are considered nowadays as promising systems for antiferromagnetic spintronic and spin-orbitronic devices. Here, the temperature dependences of magnetization dynamics in Co/IrMn and Co/FeMn F/AF structures are investigated using ferromagnetic resonance (FMR) in comparison to a free Co layer. A strong additional decrease in the resonance field was observed in Co/IrMn with a temperature decrease attributed to the rotatable anisotropy increase, which almost vanished at room temperature. In contrast to Co/IrMn, the contribution of the rotatable anisotropy in Co/FeMn is much weaker, even though it exists at RT, it is negative, and slightly varies with the temperature and resonance field shift in Co/FeMn. This is mainly due to unidirectional exchange anisotropy. FMR linewidth for the free Co layer increases with decreasing temperature and is accompanied with a slow relaxation process, while the additional contribution to FMR line broadening in Co/IrMn and Co/FeMn structures is correlated with variation in the exchange anisotropy. The observed results are discussed based on structural and surface morphology and magnetization reversal characterization using X-ray diffraction, atomic force microscopy, and vibrating sample magnetometry data.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135197923","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}
The ceramic perovskite Sr2FeNbO6-δ was synthesized via the solution combustion precursor method. X-ray phase analysis showed that the sample is single-phase and does not contain impurities. The specific heat capacity and the Mössbauer spectra were measured for the Sr2FeNbO6-δ ceramic in the temperature range of 4–300 K. The observation of an asymmetric doublet in the Mössbauer spectra and the literature data on the magnetic susceptibility indicated the presence of two magnetic subsystems in Sr2FeNbO6-δ with antiferromagnetic exchange interactions. Based on the analysis of the temperature dependence of the specific heat capacity, we determined the Debye and Einstein temperatures.
{"title":"Phase Separation in the Double Perovskite Sr2FeNbO6-δ","authors":"Daniil Popov, Ruslan Batulin, Mikhail Cherosov, Farit Vagizov, Almaz Zinnatullin, Tatiana Chupakhina, Yuliya Deeva, Tanmoy Maiti, Rushana Eremina","doi":"10.3390/magnetochemistry9100219","DOIUrl":"https://doi.org/10.3390/magnetochemistry9100219","url":null,"abstract":"The ceramic perovskite Sr2FeNbO6-δ was synthesized via the solution combustion precursor method. X-ray phase analysis showed that the sample is single-phase and does not contain impurities. The specific heat capacity and the Mössbauer spectra were measured for the Sr2FeNbO6-δ ceramic in the temperature range of 4–300 K. The observation of an asymmetric doublet in the Mössbauer spectra and the literature data on the magnetic susceptibility indicated the presence of two magnetic subsystems in Sr2FeNbO6-δ with antiferromagnetic exchange interactions. Based on the analysis of the temperature dependence of the specific heat capacity, we determined the Debye and Einstein temperatures.","PeriodicalId":18194,"journal":{"name":"Magnetochemistry","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135251315","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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