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We have developed a pressure calibration method in the high-pressure THz ESR system using induction coils set outside the pressure cell. The pressure is calibrated using alternating current (AC) magnetization measurements of the superconducting transition temperature of tin set inside the pressure cell with an ESR sample. The system fits the developed pressure cell with a wide frequency range of 0.05–0.8 THz. The pressure range was extended to 2.8 GPa. The ESR system was applied to the well-known cobalt Tutton’s salt $$({\text {NH}}_{4})_{2} {\rm {Co}}({\text {SO}}_{4})_{2}\cdot {\rm {6H}}_{2} {\text {O}}$$ , and its g principal values at 0 GPa were determined as $$g_{1}=6.61$$ , $$g_{2}=3.05$$ , and $$g_{3}=2.94$$ for the first time. Furthermore, we succeeded in observing the large change in these g values with pressure.

We systematically studied the zero-field splitting (ZFS) parameters of Fe(III) protoporphyrin IX chloride, or hemin, using the terahertz electron paramagnetic resonance (EPR) spectroscopy technique at ambient and high pressures. Although hemin is known as a model substance of hemoproteins, the pressure effect on the electronic structure has not yet been explored owing to the large ZFS. In this study, high-field and high-frequency EPR measurements were carried out in the frequency range up to 700 GHz and at hydrostatic pressures up to 2 GPa. At ambient pressure, multiple EPR branches were clearly observed, and the axial and rhombic components of ZFS were determined as $$D = 6.90\pm 0.01\hbox { cm}^{-1}$$ and $$E = 0.055 \pm 0.005\hbox { cm}^{-1}$$ , respectively. Upon pressure application, we observed a systematic shift of the resonance field, indicating a monotonous increase of the axial component from D = 6.9 to 7.9 $$\hbox {cm}^{-1}$$ at 2 GPa. The origin of this unusually large shift was discussed from a microscopic viewpoint of the electronic structure of iron under pressure.

We have developed a high-pressure electron spin resonance probe and successfully installed into the world’s highest-field cryogen-free superconducting magnet having a maximum central field of 24.6 T. The high pressure of 2.5 GPa is achieved by the specially designed piston-cylinder pressure cell using THz-wave-transparent components. In the first application of this high-pressure high-field ESR system, we observed that the orthogonal dimer spin system SrCu2(BO3)2 undergoes a quantum phase transition from the dimer singlet ground to the plaquette singlet ground states.

High-field electron spin resonance measurements of perovskite compound YCrO3 powder have been performed to obtain the magnetic anisotropy. Isotropic absorption lines of electron paramagnetic resonance, which can be described as single Lorentzian shape, are observed. The g value of paramagnetic state is estimated to be 1.983 at 265 K. Magnitude of D vector of Dzyaloshinskii–Moriya interaction is estimated to be 0.36 K from Moriya’s formula using the obtained g value. Powder patterns of antiferromagnetic resonance (AFMR) with large antiferromagnetic gaps are observed below T N = 140 K. Two antiferromagnetic gaps at zero field have been estimated to be 181 GHz (6.5 T) and 338 GHz (12.1 T), and a spin flop transition field have been estimated to be 3.5 T from widely observed frequency–field diagram at 1.9 K. Although obtained AFMR modes seem to be typical AFMR modes of two sublattice antiferromagnet with triaxial magnetic anisotropy, the obtained zero-field gap is twice as large as the obtained spin flop transition field which suggests the unconventional antiferromagnetic order.

The S = 1/2 kagome-lattice antiferromagnet is investigated by the numerical diagonalization of 18-spin finite-size cluster. The matrix elements proportional to the intensity of the singlet--triplet electron spin resonance (ESR) transition are calculated in the presence of the Dzyaloshinsky--Moriya interaction. Some angle-dependent selection rules are also proposed. The present result would be useful to examine whether the kagome-lattice antiferromagnet has a spin gap or not, with the ESR experiment.

We have developed the high-pressure electron spin resonance (ESR) system using a micro-coil in the frequency region up to around 2 GHz and potentially 10 GHz. The hybrid-type piston-cylinder pressure cell whose maximum pressure reaches 4 GPa was used. In this study, we obtained ESR spectra at 2.3 GPa successfully, which can never be obtained by the single-layer piston-cylinder pressure cell. The minimum detectable spin number was estimated to be the order of 1012 spins/G. Moreover, it is shown that the sensitivity can be improved by two orders of magnitude using the field modulation technique. This high-pressure ESR technique is a promising one to achieve the sensitivity and the high pressure simultaneously.

To develop a new spin-crossover functional material, a magnetic hybrid compound [Fe(qsal)(2)][Ni(mnt)(2)] was designed and synthesized (Hqsal = N-(8-quinolyl)salicylaldimine, mnt = maleonitriledithiolate). The temperature dependence of magnetic susceptibility suggested the coexistence of the high-spin (HS) Fe(III) cation and pi-radical anion at room temperature and a magnetic transition below 100 K. The thermal variation of crystal structures revealed that strong pi-stacking interaction between the pi-ligand in the [Fe(qsal)(2)] cation and [Ni(mnt)(2)] anion induced the distortion of an Fe(III) coordination structure and the suppression of a dimerization of the [Ni(mnt)(2)] anion. Transfer integral calculations indicated that the magnetic transition below 100 K originated from a spin-singlet formation transformation in the [Ni(mnt)(2)] dimer. The magnetic relaxation of Mossbauer spectra and large thermal variation of a g-value in electron paramagnetic resonance spectra below the magnetic transition temperature implied the existence of a magnetic correlation between d-spin and pi-spin.

A hybrid-type piston-cylinder pressure cell for the electron spin resonance (ESR) measurement has been developed. The cylinder of this pressure cell consists of a NiCrAl inner cylinder and a CuBe outer sleeve, and all inner parts are made of zirconium oxide which has good transmittance to the millimeter and submillimeter waves. We confirmed that the pressure reaches 2.1 GPa. We have also developed a transmission-type high-field ESR system having two different modulation methods for this pressure cell. A test measurement without pressure cell for the two-dimensional orthogonal-dimer spin system of SrCu2(BO3)2 has been done successfully in the wide frequency region. The combination of this electromagnetic wave transmission-type pressure cell and this high-field ESR system is a promising tool for the study of the pressure-induced phase transition of SrCu2(BO3)2.

We perform photoluminescence measurement of GaAs:Er,O under a pulsed magnetic field up to 60 T and succeed to obtain the magnetic field dependence of three main photoluminescence peaks. We also estimate the energy splitting of states 4I15/2 and 4I13/2 using the crystal field theory. Theoretically calculated energy differences between the lowest state of J= 13 2 and the lowest three states of J= 15 2 are in good agreement with experimentally obtained energy of three main PL peaks. We discuss the local configuration around the luminescent Er-2O center. By using parameters in the crystal field calculation, our analysis suggest that not only O2− sites but also As3− sites adjacent to Er3+ ion are displaced from their original lattice positions.

High-frequency electron spin resonance (ESR) measurements of S = 1/2 one-dimensional Heisenberg antiferromagnetic zig-zag chain substance (VO)(SO4)(2,2-bpy) were performed in the temperature region from 1.8 to 265 K. ESR measurements at 265 K show typical powder pattern spectra of the V4+ ion and g || = 1.925 ± 0.001 and g ⊥ = 1.976 ± 0.001 were obtained. Although the magnetic susceptibility shows a maximum at 3.1 K suggesting the existence of a short-range order, no g-shift and line width broadening were observed down to 1.8 K. We suggest that these temperature-independent features of ESR can be attributed to the result of frustration in (VO)(SO4)(2,2-bpy).

Magnetic interactions in a site-disordered multicomponent vanadate Mn3Fe4(VO4)6 are studied using DC magnetization and multifrequency Electron Paramagnetic Resonance (EPR). The static magnetic susceptibility χ shows antiferromagnetic interactions between Fe3+ and Mn2+ spins with a Curie–Weiss temperature Θ = −165(5) K. EPR measurements indicate a strong dependence of χ on the frequency and temperature. The EPR spectra due to iron and manganese ions are observed in the X-band. It is mostly manganese ions that are observed at 80 GHz while two kinds of magnetic centers are identified at frequencies above 160 GHz. The observed shifts of the resonance lines for Fe3+ ions at low frequencies differ from those at high frequencies. The observed features may be due to different magnetic sublattices which modify the magnetic ground state, while competing magnetic interactions may lead to magnetic frustration. It appears that the very high magnetic fields employed in our high-frequency EPR measurements may affect the spin-flop transitions anticipated below Neel temperature TN.

A multiextreme (high-field, low-temperature, high-pressure and nanoscale) electron spin resonance (ESR) measurement system is under development in Kobe. In this connection, our recent development is introduced and two applications of our high-frequency high-field ESR are described. High-frequency high-field ESR measurements of dioptase (Cu6Si6O18·6H2O), which has an interesting antiferromagnetic Cu2+ network, have been performed using a pulsed magnetic field of up to 55 T. Antiferromagnetic resonances (AFMR) are clearly observed at 4.2 K with the light sources of up to 1017 GHz. However, a deviation from the conventional two-sublattice AFMR theory is observed in the high field. Temperature dependence of the X-band and high-frequency ESR has been also observed in the triangular lattice antiferromagnet EtMe3P[Pd(dmit)2]2 which shows the spin-Peierls-like transition below Tc = 25 K. The preliminary field dependence of the spin gap estimated from the analyses of our ESR results has been shown in connection with the previous magnetic susceptibility results.

We report the anomalous effect of the polarization dependence of electron paramagnetic resonance absorption in CuGeO3 doped with 2% of Co. While the resonance line of Cu2+ chains is independent of the microwave polarization in the Faraday geometry, the resonant mode of Co impurity exhibits a strong polarization dependence for all directions of the external magnetic field. Possible reasons of such behavior are discussed.

A new piston-cylinder pressure cell for electron spin resonance (ESR) has been developed. The pressure cell consists of a double-layer hybrid-type cylinder with internal components made of the ZrO2-based ceramics. It can generate a pressure of 2 GPa repeatedly and reaches a maximum pressure of around 2.5 GPa. A high-pressure ESR system using a cryogen-free superconducting magnet up 10T has also been developed for this hybrid-type pressure cell. The frequency region is from 50 GHz to 400 GHz. This is the first time a pressure above 2 GPa has been achieved in multi-frequency ESR system using a piston-cylinder pressure cell. We demonstrate its potential by showing the results of the high-pressure ESR of the S=1 system with the single ion anisotropy NiSnCl6·6H2O and the S=1/2 quantum spin system CsCuCl3. We performed ESR measurements of these systems above 2 GPa successfully.

We have developed a high field and high pressure ESR system including a unique pressure calibration method. We have succeeded in the ESR measurements up to 16 T under the pressure region up to 1.1 GPa. We will present about the ESR system and its application to a spin gap system KCuCl3. The energy gap between the singlet ground state and the triplet excited states are suppressed with applying pressure and the critical pressure of KCuCl3is estimated to be 0.90 GPa at 4.2 K.

The magnetic field of the high field ESR system in Kobe University has been extended to 55 T by using a new non-destructive pulse magnet and the 300 kJ (10kV) capacitor bank. The properties of new 55 T pulse magnet are reported. As an example of its application, the high field ESR measurement of a quantum spin system CsCuCl3 for H∥a will be shown.

New Co spinel compound SiCo2O4 have been synthesized by using the high-pressure synthesis technique. High frequency ESR measurements of powder samples of SiCo2O4 have been performed by using the pulsed magnetic field up to 16 T in the frequency range from 60 GHz to 540 GHz. From the frequency-field diagram at 1.8 K two critcal field resonances are observed at 1.7 T, which correspond to the field of the metamagnetic transition and 2.3 T. The g-values are estimated to be 6.7 and 4.5 from the ESR mode in the field induced ferromagnet phase. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

High field ESR measurements of LiCrTiO4 polycrystalline have been performed in the frequency region from 60 GHz to 160 GHz and in the temperature region from 1.8 K to 265 K. An isotropic absorption line is observed. The g-value in the high temperature region is determined to be 1.98 which is a typical value for Cr3+ ion. The g-shift is observed below 20 K, and it continues blow 2.7 K which corresponds to the temperature of the spinglass phase transition. The increase of linewidth is observed below 50 K. These temperature dependences are discussed in connection with other frustrated systems. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Submillimeter and millimeter wave ESR measurements of one-dimensional CuO2 chain system Ca2Y2Cu5O10 have been performed using the pulsed magnetic field up to 16 T. The g-values are estimated to be g‖ = 2.31 and g⊥ = 2.03 from the powder pattern analysis. Obtained frequency-field diagram at 1.8 K is well described by an antiferromagnetic resonance mode with an uniaxial anisotropy. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Submillimeter and millimeter wave ESR measurements of spin gap systems SrCu 2 (PO 4 ) 2 and PbCu 2 (PO 4 ) 2 , which have four kinds of dimers, have been performed to investigate the magnetic properties of spin gap systems using the pulsed magnetic field up to 35T. The observed ESR spectra of powder sample SrCu 2 (PO 4 ) 2 show sharp and single peak in the temperature range from 4.2 to 80 K. The anisotropy of the g -values turned out to be very small compared to the usual anisotropic powder spectra of copper compounds. The dynamical properties will be discussed from the temperature dependence measurements.

The changes of the homogenization temperature (Th), when hydrocarbons in inclusions were cracked thermally, were experimentally evaluated. In the experiments, the hydrocarbon-inclusions in quartz were heated in an autoclave, and the Th between before and after heating were compared. In the experiments, the Th decreased after heating. The amount of decrease became greater as the heating temperature or the duration time or both increased. The experiments also revealed that the samples with higher Th showed a greater decrease after heating. Because the experiments have been performed in a closed system, mass transfer between inclusions and the enclosing medium was impossible. No volumetric changes in the hydrocarbon inclusions were observed after heating. Therefore, the temperature depression after heating should be caused by the pyrolysis of the hydrocarbons in the inclusions. In the Shin-Kumoide SK-1D well of the Niigata oil and gas field in Japan, the Th of hydrocarbon inclusions decreases from 73 to 30 °C between 4040 and 4810 m in depth successively. This temperature range is lower than the present formation temperature by from 60 to 140 °C, and shows a trend opposite to the normal geothermal gradient. Therefore, it should reflect the degree of the thermal cracking after trapping rather than the trapping temperature.

Resonance magnetoabsorption spectra of CuGeO3 single crystals containing 2% Co impurity have been studied in the frequency range 60–360 GHz in magnetic fields of up to 16 T and in the temperature interval 2–60 K with the magnetic field B aligned parallel to the a crystallographic axis. In addition to the Cu2+ chain resonance, a new absorption line (unobserved previously in doped CuGeO3 and deriving apparently from the Co2+ ions) was detected in EPR spectra. Quantitative analysis of the spectra suggests that the spin-Peierls transition occurs in about 10% Cu2+ chains, while the spin-Peierls state in the remaining 90% chains is completely destroyed by cobalt doping. The results obtained reveal considerable deviations from the universally accepted scenario of CuGeO3 doping and are discussed within alternative theoretical models, namely, the quantum critical behavior (based on the EPR theory for quasi-one-dimensional systems) and a three-dimensional antiferromagnet with the Neel temperature lowered by disorder.

Intensive high-field ESR studies have been performed to investigate the peculiar ground state of a quasi-one dimensional cupric oxide Ca 1- x CuO 2 ( x =0.164), to which a two-sublattice model (chain-dimer model) composed of a Heisenberg antiferromagnetic chain and dimer state with low spin density is proposed from the results of magnetic susceptibility and specific heat measurements. Using the powder sample and high frequency sources from 60 to 490 GHz, we observed antiferromagnetic resonance mode with a typical frequency–field relation of the easy-axis type at 1.8 K. Moreover, weak ESR signals are also observed in the ordered state. From the analysis of the integrated intensity for those weak signals, it is found that the dimer model reproduces the temperature dependent behaviors quite well. These results support the chain-dimer model from the microscopic point of view.

Magnetisation study of the C60·TMTSF·2CS2 molecular complex in magnetic field up to 47 T for the temperature range 1.8–300 K and ESR spectroscopy of the molecular complex (ET)2C60 at T=1.8 K for the frequency range 60–90 GHz in magnetic field up to 32 T provide the experimental evidence that a paramagnetic centers with the reduced g-factor values g

X-band ESR measurements of BIP-TENO (3,3 ′ ,5,5 ′ -tetrakis( N -tert-butylaminoxyl)biphenyl) single crystal, which is an S =1 spin ladder model substance, have been performed in the temperature reg...

We developed a new high-field ESR system under pressure. A clamped-type pressure cell with sapphire pistons is used to transmit the electromagnetic wave. The first measurements on the spin–Peierls system CuGeO3 under pressure and our development of the new standard of pressure for high-field ESR are presented.

High field ESR measurements of S =1/2 one-dimensional quantum antiferromagnetic (AF) system BaCu 2 (Si 1− x Ge x ) 2 O 7 have been performed using powder samples and pulsed magnetic field. High field electron paramagnetic resonance at 352 GHz and 86 K enabled us to determine the x dependence of g -values even when we used the powder samples. The x dependence will be discussed in connection with the crystal field. Moreover, antiferromagnetic resonances of x =0 and x =1 samples below T N were observed and their frequency–field relations suggest the existence of Dzyaloshinsky–Moriya interaction.

We have performed millimeter wave ESR measurements of (DMET) 2 FeBr 4 single crystals, which consist of electric quasi 1D chain-based donor layers and magnetic Fe 3+ square lattices, in the temperature region from 1.8 K to 70 K. We observed the splitting of absorption line at 130 GHz, and the estimate the exchange interaction between d -electrons and ~ -electrons. The temperature dependence of ESR at low temperature is discussed in connection with the conventional antiferromagnetic resonance (AFMR). DMET ~ - d system high field ESR

We have performed the frequency dependence millimeter wave ESR measurements on Et 2 Me 2 P[Pd(dmit) 2 ] 2 single crystals at 4.2 K. Antiferromagnetic resonance (AFMR) was observed for B // a and c . The hard axis is determined to be a axis by AFMR mode analyses. This result will be discussed in connection with the X- and Q-band ESR results at low temperature. We will also discuss about the magnetic anisotropy of the system and it turned out that this salt is the antiferromagnet with the easy axis type anisotropy. millimeter wave ESR dmit AFMR magnetic anisotropy

High-field electron spin resonance measurements of an antiferromagnet Ca3ZnMnO6 isostructure, with the Ising-chain multiferroic Ca3CoMnO6, have been carried out. Two distinct resonance modes were observed below TN = 25 K, which is well explained by conventional antiferromagnetic resonance theory with easy-plane anisotropy. The zero-field spin gap is derived to be about 166 GHz, originating from the easy-plane anisotropy and exchange interaction. Our result suggests that the Dzyaloshinsky-Moriya interaction, which may induce spin canting, is absent. Disappearance of Ising anisotropy in Ca3ZnMnO6 suggests that the Co(4+) ion, as well as the Co-Mn superexchange, plays an important role for the Ising nature in Ca3CoMnO6.

Cyclotron resonance (CR) measurements of heavily doped Si : Mn prepared by chemical vapour deposition have been performed at 4.2 K by our high field CR measurement system equipped with a UV light illumination. The system is equipped with a pulsed magnetic field up to 16 T and light sources from 30 GHz to 700 GHz. The field dependence of the effective masses and linewidths of CRs at 4.2 K are discussed in connection with those observed by a conventional X-band ESR measurement system at 3.4 K under UV light illumination.

Due to the existence of strong spin frustration in a system, the spin dynamics of S= 1/2 kagome lattice antiferromagnet at low temperature has attracted much interest. High-field ESR has been measured on its model substances, Cu 3 V 2 O 7 (OH) 2 · 2H 2 O (volborthite) and BaCu 3 V 2 O 3 (OH) 2 (vesignieite), down to 1.8 K using pulsed magnetic fields up to 16 T. The measurements are performed for 160 and 315 GHz using polycrystalline samples. Although both samples showed the g-shift and the change of linewidth at low temperature, volborthite showed a small gap excitation of the order of 40 GHz (1.9 K) while vesignieite showed a paramagnetic behavior down to 1.9 K. Observed difference will be discussed in connection with the crystal structure, and the possible spin liquid state in vesignieite will be discussed.

Quasi-one-dimensional (1-D) cupric oxide Ca1−xCuO2 (x = 0.164) is the system with 25–40% hole-doped edge-sharing CuO2 chains. However, the holes are almost localized in Ca1−xCuO2 and its magnetic susceptibility with a peak at 30 K was explained by the model considering both 1-D antiferromagnetic chains and spin dimers (Z. Hiroi, M. Okumura, Y. Nabeshima, T. Yamada, M. Takano: J. Phys. Soc. Jpn.69, 1824, 2000). To clarify the magnetic nature of Ca1−xCuO2, we performed submillimeter-wave electron spin resonance (ESR) measurements on a powder sample of Ca0.83−6CuO2. The resonance above 12 K showed typical powder ESR of Cu2+ and theg-values were determined to be g∥= 2.33 and g⊥ = 2.06 from the analysis. The resonance below 12 K changed completely from ESR. The frequency-field relation of ESR at 1.8 K clearly showed the easy-axis type antiferromagnetic resonance.

Temperature-dependent electron spin resonance (ESR) measurements of two low-dimensional quantum spin systems, theS = 1/2 spin-ladder system Cu2(1,4-diazacycloheptane)2Cl4 (Cu2(C5H12N2)2Cl4) and the gaplessS = 1 bond-alternating one-dimensional antiferromagnettrans-Ni(333-tet)(N3)(ClO4), have been performed. X-band electron spin resonance (ESR) measurements of single-crystal Cu2(C5H12N2)2Cl4 show the increase of linewidth and anisotropicg-shifts below 8 K similar to those known for one-dimensional antiferromagnet. On the other hand, Ni(333-tet)(N3)(ClO4) has broad line-width and ESR has been observed for the first time by our high-field ESR. Its linewidth increases as the temperature is decreased, while theg-shift seems to be isotropic and theg-value decreases as the temperature is decreased. Thisg-shift can be connected to the quantum fluctuation of the system.

Lu2Cu2O5 is a related substance of Y2Cu2O5 which is an unusual copper oxide with two successive metamagnetic transitions. We have performed the antiferromagnetic resonance (AFMR) measurements of Lu2Cu2O5 in the millimeter and submillimeter wave region with the pulsed magnetic field up to 16 T at 1.8 K. Our measurements this time are very detailed frequency dependence measurements compared to the previous measurement and we found new AFMR modes which were not observed previously. From the analysis of the observed AFMR modes, we found that the magnetic phase aboveH cl = 3.1 T in Lu2Cu2O5 is different from that in Y2Cu2O5.

High field ESR measurements have been performed on newly synthesized layered manganese oxides A 4 Mn 3 O 10 (A=Ba, Sr) using a pulsed magnetic field up to 16 T. From the temperature and the frequency dependence measurements, it was confirmed that both ground states at low temperature are the antiferromagnetic ordered state. The typical AFMR absorption lines were observed for both compounds and both were well explained by the AFMR theory for a two-sublattice antiferromagnet with orthorhombic magnetic anisotropy. Moreover, we found that the magnetic anisotropy energies in these compounds are very small as compared with their exchange interactions.

ESR measurements have been performed on KCuCl3 and TlCuCl3 in the frequency range up to 762 GHz and field range up to 30 T at helium temperatures. The exchange network in the present systems is described as an S= 1 2 Heisenberg spin ladder along the a-axis with an additional diagonal interaction. Both compounds have a singlet ground state with an excitation gap. In KCuCl3, two kinds of transitions are observed between the ground state and the excited triplet states. They correspond to the excitations at Q=(1, 0, 1) and (0.5, 0, 1) with the excitation energies Δ≈640 and 1080 GHz, respectively. When the external field is increased, the frequency of the lowest branch with the zero-field gap Δ≈640 GHz decreases linearly with a tendency toward zero at Hc≈22 T. In TlCuCl3, a transition from the singlet ground state to the excited triplet state is observed. The zero-field gap is determined as Δ≈160 GHz.

The magnetic ground state of Sr2CrO4 with a distorted honeycomb lattice was investigated by means of measurements of the magnetic susceptibility, high-field magnetization process, and electron spin resonance (ESR). Antiferromagnetic ordering was observed clearly below TN?=?3.2?K, while the magnetic ground state had been thought to be a spin-singlet state. A two-sublattice model with biaxial anisotropy was applicable for the observed ESR modes. Plateau-like behavior and a sharp kink were detected in the magnetization curve.

Metal-forest patterns of electroless deposits of silver and gold in thin-layer aqueous solutions were studied in connection with their chemical reactions. While the silver metal-forest with a simple redox reaction of Cu and Ag+ showed a DLA (diffusion limited aggregation)-like pattern, the gold metal-forest with a redox reaction of Pb and [Formula: see text] showed a DBM (dense branching morphology). The reaction mechanism of the latter was investigated by means of cyclic voltammetry, and the growth condition of the DBM is discussed.

We have developed a high-pressure and high-field electron spin resonance (ESR) system using the combination of a commercially available superconducting quantum interference device (SQUID) magnetometer and a clamp-type piston cylinder pressure cell. The magnetic field range is up to 5 T, and the maximum pressure reaches 1.5 GPa. The most characteristic feature of this system is its easy handling as compared with other high-pressure ESR systems. Moreover, the macroscopic magnetization measurement can be performed simultaneously with the microscopic ESR measurement. In addition to these features, the well-established pressure calibration method utilizing the change of superconducting transition temperature of tin can be applied to this system. By using this system, we obtained pressure dependence of the single ion magnetic anisotropy parameter D of NiSnCl 6 ·6H 2 O up to 1.5 GPa precisely, and the magnetization behavior of this material under pressure was explained well by its pressure dependence of the D value.

The magnetic field effect on the morphology of electrodeposited zinc was investigated in a thin-layer ZnSO 4 aqueous solution. The growth morphology drastically changed from DLA-like and dendritic patterns in 0T to a spiral pattern and an asymmetric dendrite in magnetic fields lower than 0.5T, respectively, and both patterns changed into a dense and compact one in magnetic fields higher than 1T.

Non-radioisotopic reverse transcriptase assay (Non-RTA) was successfully applied for detection and identification of the retroviruses isolated from peripheral mononuclear cells from eight HIV-1-seropositive hemophiliac patients. Of 40 samples, 36 (90%) were consistent in detection between Non-RI and RI RTA. Four samples which showed RT activities slightly above the cutoff level of RI RTA were not detected by Non-RI RTA. Non-specific RT-inhibitors in the culture supernatant decreased the sensitivity of Non-RI RTA more significantly than that of RI RTA. It was demonstrated that higher concentrations (> 20%) of fetal calf serum in RPMI-1640 culture medium inhibited the hybridization of poly rA template with immobilized primer, resulting in reducing the sensitivity of Non-RI RTA. Then we identified the isolated retroviruses using specific RT-inhibiting (RTI) antibodies against HIV-1 and HIV-2. HIV-1 RTI antibody specifically inhibited RTs of isolated retroviruses and HIV-1 strain, LAV-1, but not HIV-2 and Rous-associated virus 2 (RVA-2) RT. Conversely, HIV-2 RTI antibody specifically inhibited HIV-2 RT, but not HIV-1 and RAV-2 RT. These findings agreed with previously reported results showing the type-specificity of HIV-1 and -2 RTI antibodies, and suggest the possibility that isolated retroviruses could be identified by these antibodies.

Natural mineral Dioptase (Cu6Si6O18 ⋅ 6H2O) is an S = 1/2 antiferromagnet with a unique spin network which consists of helical chains along the c axis connected by inter chain exchange interactions. In order to study the ground state of dioptase, we have performed the magnetization measurement for B//c (easy axis) at 1.5 K and have found the spin-flop transition at 13 T. Moreover, the pressure effect of the magnetic susceptibility is investigated up to 1.78 GPa using the SQUID magnetometer where TN increased while the broad maximum reflecting the low dimensionality of the system decreased by pressure. The results will be discussed in connection with our previous antiferromagnetic resonance (AFMR) measurement results and the phase diagram obtained by Gros et al.

This paper deals with the analysis of the temperature dependence of high-frequency EMR (HF-EMR) spectra due to Mn3+ and Mn4+ ions in the lithium manganese spinel LiMn2O4. A range of powder samples obtained by the sol-gel method with calcinations in several temperature ranges were prepared for this study. Based on the initial characterization carried out by a number of techniques, the physicochemical and structural properties of the samples were earlier determined. Independently, temperature magnetization and HF-EMR measurements were carried out. The EMR spectra vary strongly between samples, indicating possible structural or chemical changes. Quantitative analysis of the temperature dependence of the HF-EMR spectra due to Mn3+ and Mn4+ ions in LiMn2O4 is presented in this paper. The spectral analysis concerns the line shape, linewidth, intensity and g-factors. Fittings using the Lorentzian spectral shape and, to a certain extent, the Gaussian spectral shape have been carried out in order to parameterize the temperature dependence of the HF-EMR spectra. This parameterization of the HF-EMR experimental data enables a deeper characterization of the samples. Subsequently, a better insight into the role of the Mn3+ and Mn4+ ions in accounting for the characteristics most suitable for application of LiMn2O4 as a cathode material may be gained.

Submillimetre and millimetre wave electron spin resonance (ESR) measurements of LiMn 2 O 4 powder samples have been performed using a pulsed magnetic field up to 16 T in the temperature region from 4.2 to 265 K. Although competition between spin and charge orderings of Mn ions on the octahedral B sites of lithium manganese spinel is expected, geometrical frustration is also expected in LiMn 2 O 4 because the octahedral B sites form the pyrochlore lattice. LiMn 2 O 4 calcined at 600 °C was employed in this study because it turned out to be stoichiometric and have fewer impurities. The detailed temperature dependence of the submillimetre and millimetre wave ESR of this sample will be given and its spin dynamics will be discussed.

High field ESR measurements of LiMn2O4 powder samples, which are obtained by the sol-gel method with calcinations at 700 and 850 °C, have been performed under the pulsed magnetic field up to 16 T and in the temperature region from 4.2 to 300 K. Analysis of the obtained data in connection with the magnetic susceptibility and our previous ESR data shows that the high field ESR is a powerful means for the characterization of LiMn2O4 powder samples. Our result shows that the impurity phase Li2MnO3 already exits in the sample obtained by calcinations at 850 °C and the sample obtained by calcinations at 600 °C is close to the stoichiometry. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

High field ESR measurements of powder and aligned samples of MCuP2O7 (M = Sr, Pb) have been performed in the temperature range from 1.7 K to 265 K in the frequency range from 40 GHz to 370 GHz. A typical powder absorption line of Cu2+ is observed in the case of the powder sample. We have found that the g values increase with decreasing temperature below 10 K and these g‐shift directions are not consistent with the ESR theory of Nagata‐Tazuke for the one dimensional antiferromagnet. A frequency dependence of the g‐shift is also observed.

ESR measurements of a quantum spin gap system KCuCl3 have been performed under multi extreme conditions which consist of high field, high pressure and low temperature. The ESR mode due to the direct transition from the singlet ground state to the triplet excited states is observed and we have succeeded in observing the decrease of the gap energy by applying pressure directly.

We have performed high field ESR measurements of a F5PNN (2‐pentafluorophenyl‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1 H‐imidazol‐1‐oxyl 3‐oxide) powder sample, which forms a one dimensional (1D) bond alternating chain along the (1 0 1) direction, in order to clarify the magnetic properties at low temperature. The frequency dependence of our ESR measurements shows an anomaly in the width of the absorption line at Hc = 3.7 T, where the magnetization data shows a bond alternating ratio change from α = 0.4 to 0.5, and an abrupt broadening of the absorption line around the saturation field found from the magnetization measurements.