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In zero magnetic field, the famous neutron spin resonance in the f-electron superconductor CeCoIn5 is similar to the recently discovered exciton peak in the non-superconducting CeB6. Magnetic field splits the resonance in CeCoIn5 into two components, indicating that it is a doublet. Here we employ inelastic neutron scattering (INS) to scrutinize the field dependence of spin fluctuations in CeB6. The exciton shows a markedly different behavior without any field splitting. Instead, we observe a second field-induced magnon whose energy increases with field. At the ferromagnetic zone center, however, we find only a single mode with a non-monotonic field dependence. At low fields, it is initially suppressed to zero together with the antiferromagnetic order parameter, but then reappears at higher fields inside the hidden-order phase, following the energy of an electron spin resonance (ESR). This is a unique example of a ferromagnetic resonance in a heavy-fermion metal seen by both ESR and INS consistently over a broad range of magnetic fields., 7 pages, 6 figures including one animation, accepted to Phys. Rev. B

In this work we introduce a new method of a ferromagnetic resonance (FMR) detection from thin, nm-size, films. Our setup is based on the commercial piezo-cantilever, used for atomic force microscopy. It has an option to rotate the sample in the magnetic field and it operates up to the high microwave frequencies of 160 GHz. Using our cantilever based FMR spectrometer we have investigated a set of samples, namely quasi-bulk and 84 nm film Co$_2$FeAl$_{0.5}$Si$_{0.5}$ samples, 16 nm Fe$_{50}$Ni$_{50}$ film and 150 nm Sr$_2$FeMoO$_6$ film. The high frequency ferromagnetic resonance (FMR) response from an extremely thin Fe$_{50}$Ni$_{50}$ film we have fitted with the conventional model for the magnetization dynamics. The cantilever detected FMR experiments on Sr$_2$FeMoO$_6$ film reveal an inability of the conventional model to fit frequency and angular dependences with the same set of parameters, which suggests that one has to take into account much more complicated nature of the magnetization precession in the Sr$_2$FeMoO$_6$ at low temperatures and high frequencies. Moreover, the complicated dynamics of the magnetization apparent in all investigated samples is suggested by a drastic increase of the linewidths with increasing microwave frequency, and by an emergence of the second line with an opposite angular dependence., Comment: Submitted to Journal of Magnetic Resonance

A single crystal S=3/2 perfect kagome lattice antiferromagnet $\mathrm{KCr_3(OH)_6(SO_4)_2}$ (Cr-jarosite) has been studied by X-band and high-frequency electron spin resonance (ESR). The g-values perpendicular to the kagome plane (c-axis) and in the plane are determined to be $g_c=1.9704 \pm 0.0002$ and $g_\xi=1.9720 \pm 0.0003$, respectively, by high-frequency ESR observed at 265 K. Antiferromagnetic resonances (AFMR) with the antiferromagnetic gap of 120 GHz are observed at 1.9 K, which is below $T_N$=4.5 K. The analysis of AFMR modes by the conventional molecular field theory shows $d_p=0.27$ K and $d_z=0.07$ K, where $d_p$ and $d_z$ are in-plane and out-of-plane components of DM d vector, respectively. From these results and the estimated exchange interaction J=6.15 K by Okuta et al., the ground state of Cr-jarosite is discussed in connection with the Monte Carlo simulations result with classical Heisenberg spins on the kagome lattice by Elhajal et al. Finally, the angular dependence of linewidth and the lineshape observed at 296 K by X-band ESR show typical behavior of a two-dimensional Heisenberg antiferromagnet, suggesting a good two-dimensionality of Cr-jarosite.

Vapor- and gas-responsive ionic liquids (ILs) comprised of cationic metal-chelate complexes and bis(trifluoromethanesulfonyl)imide (Tf(2)N) have been prepared, namely, [Cu(acac)(BuMe(3)en)][Tf(2)N] (1 a), [Cu(Bu-acac)(BuMe(3)en)][Tf(2)N] (1 b), [Cu(C(12)-acac)(Me(4)en)][Tf(2)N] (1 c), [Cu(acac)(Me(4)en)][Tf(2)N] (1 d), and [Ni(acac)(BuMe(3)en)][Tf(2)N] (2 a) (acac = acetylacetonate, Bu-acac = 3-butyl-2,4-pentanedionate, C(12)-acac = 3-dodecyl-2,4-pentanedionate, BuMe(3)en = N-butyl-N,N',N'-tetramethylethylenediamine, and Me(4)en = N,N,N',N'-trimethylethylenediamine). These ILs exhibited reversible changes in color, thermal properties, and magnetic properties in response to organic vapors and gases. The Cu(II)-containing ILs are purple and turn blue-purple to green when exposed to organic vapors, such as acetonitrile, methanol, and DMSO, or ammonia gas. The color change is based on the coordination of the vapor molecules to the cation, and the resultant colors depend on the coordination strength (donor number, DN) of the vapor molecules. The vapor absorption caused changes in the melting points and viscosities, leading to alteration in the phase behaviors. The IL with a long alkyl chain (1 d) transitioned from a purple solid to a brown liquid at its melting point. The Ni(II)-containing IL (2 a) is a dark red diamagnetic liquid, which turned into a green paramagnetic liquid by absorbing vapors with high DN. Based on the equilibrium shift from four- to six-coordinated species, the liquid exhibited thermochromism and temperature-dependent magnetic susceptibility after absorbing methanol.

Recent developments of “multi-extreme” high magnetic field electron spin resonance (ESR) in Kobe will be reviewed. Our high magnetic field ESR covers the frequency region between 0.03 and 7 THz and the temperature region between 1.8 and 300 K. With this high magnetic field ESR system we can apply the magnetic field up to 55 T using a Cu-Ag pulsed magnet and a 300 kJ (10 kV) capacitor bank. Under this high magnetic field we can also apply the high pressure up to 1.4 GPa. As we can make the measurement under low temperature, high magnetic field and high pressure simultaneously, we name it as “multi-extreme” ESR. Moreover, in order to gain the sensitivity of our high magnetic field ESR, we have developed a micro-cantilever ESR system using a torque method, which enables the ESR measurement of micrometer size single crystal at low temperature. At the moment we are in the process of extending the magnetic field region of micro-cantilever ESR. Recently we have succeeded in making the measurement up to 369 GHz and the achieved sensitivity is about 1010 spins/G, which is much higher than that using the conventional transmission method. Finally our development of magnetization detected ESR using SQUID magnetometer (SQUID ESR) will be also presented.

Alkali metal salts of 7,7′,8,8′-tetracyanoquinodimethane (TCNQ) reversibly absorb iodine forming the ternary salts M(TCNQ)I (M = Li, Na, K) and M2(TCNQ)3I2 (M = Rb). The ternary salts are also obtained by solid-state reactions of TCNQ with alkali iodides. These salts are paramagnetic and have high electrical conductivities, ∼10−1 S cm−1, for compacted pellets, whereas the alkali metal salts of TCNQ are diamagnetic insulators. The ternary salts further absorb iodine to give over-doped salts M(TCNQ)In (n ≈ 6, M = Na, K), which gradually release iodine to give M(TCNQ)I. In contrast, the solid-state reaction of F4TCNQ and sodium iodide produces Na(F4TCNQ), which does not exhibit iodine absorption.

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.

Organometallic charge-transfer salts composed of decamethyl-, octamethyl-, and dimethylferrocene with N,N′-dicyano-1,4-benzoquinonediimine (DCNQI) derivatives were prepared. [Fe(C5Me5)2][(MeO)2DCNQI] (1) and [Fe(C5Me4H)2][Me2DCNQI] (2) were 1:1 DA salts with mixed-stack structures, whereas [Fe(C5Me4H)2][(MeO)2DCNQI]2 (3) and [Fe(C5MeH4)2][DCNQI]2 (4) were 1:2 DA salts. 3 exhibited a segregated-stack structure, in which charge separation was observed in the acceptor column. 1 became a metamagnet below TN = 5.0 K, whereas the other salts were paramagnets. Valence states and charge-transfer (CT) transitions in these complexes are discussed based on the neutral–ionic (NI) phase diagram.

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).

Highly oriented pyrolytic graphite (HOPG) samples were irradiated by highly charged ions Ar11+ and Xe26+. Scanning electron microscopy (SEM), electron spin resonance (ESR), a superconducting quantum interference device (SQUID), and Raman spectroscopy were used to investigate the effect of this irradiation. SEM observations revealed that the contrast between irradiated and unirradiated regions became discernible at a fluence of about 1014cm -2. On the other hand, for samples irradiated by Ar+ ions, a fluence of the order of 1015cm -2 was necessary to obtain a similar contrast to that obtained by Ar11+ ion irradiation. This demonstrates that highly charged ions effectively enhance modification of solid surfaces. Furthermore, the ESR and SQUID measurements revealed the formation of defects and magnetization of the irradiated surface. Raman measurements were also performed to investigate the structural transformation at different fluences. © 2011 The Surface Science Society of Japan.

[Dineopentyl-biferrocene]2[Cl1TCNQ]7, which has an unprecedented high donor-acceptor ratio of 2 : 7, contains a linear paramagnetic hexamer of Cl1TCNQ. Both the donor and acceptor molecules exhibit charge disproportionation in the crystal through mutual electrostatic interactions.

Force detection of magnetic resonance is now able to attain extremely high spin sensitivity. In these setups, microcantilevers were usually used as a sensitive force sensor and, in most cases, have been applied to solid-state samples such as paramagnetic impurities in solids. On the other hand, there are now growing demands for their applications to liquid-state samples in the research areas of life science because many proteins and enzymes are biofunctionally active only in solutions, where they interact with the surrounding water molecules. In this letter, we present an electron paramagnetic resonance (EPR) technique for solution samples using a SiNx nanomembrane and report high-frequency EPR spectroscopy of a microliter-volume frozen solution sample of hemin and myoglobin at multiple frequencies up to 350 GHz. This technique would be particularly useful to obtain more detailed insight into the electronic structure of metalloproteins/metalloenzymes under biologically active conditions.This study was partly supported by a Grant-in-Aid for Scientific Research (A) (No. JP17H01184) to Y.M., a Grant-in-Aid for Scientific Research (B) (No. JP26287081) to E.O., a Grant-in-Aid for Challenging Exploratory Research (No. JP26610104) to H.O., and a Grant-in-Aid for JSPS Research Fellow (No. JP18J11268) to T.O. from the Japan Society for the Promotion of Science (JSPS), the Asahi Glass Foundation to E.O., the Casio Foundation to E.O., and the Shimadzu Foundation to H.T.

We performed 75As nuclear quadrupole resonance (NQR) measurements on single-crystalline Ru1−xRhxAs to study the relationship between the superconductivity observed in a limited Rh-substitution regi...

We developed a superconducting magnet which is suitable for a novel spectroscopy. The methodology of the spectroscopy was suggested by Fuke. This enables to combine NMR (Nuclear Magnetic Resonance) spectroscopy with mass spectroscopy. In order to realize the spectroscopy, the magnet needs two homogeneous regions of 12 T and 4 T, respectively. The field gradient between two regions is required to be high enough. The coil structure is robust against high stress due to such an asymmetric field. The magnet is shielded actively and has a horizontal access room temperature bore of 155 mm diameter.

For the sensor probe of high frequency magnetic field in GHz region, films were prepared by liquid phase epitaxy technique and ferromagnetic resonances were investigated in high frequency region. Magneto-optical (MO) effect of magnetic garnet was utilized for the imaging sensor of the magnetic field distribution. However, for the application to the characterization of high frequency magnetic field in the GHz frequency region, usual MO measurements are difficult to detect the magnetic filed as the decreasing of the permeability of magnetic garnet. Magnetic resonance is an effective way to induce magnetic moment and enhance the magnetooptical effect in high frequency region of GHz order. In order to understand the possibility of magnetic field sensor of high frequency in detail, far-infrared magnetic resonances were measured at the high frequencies up to 315 GHz in pulsed high magnetic field. Taking account into sensitivity of MO signals and magnetic resonance intensities, magnetooptical method using a garnet film is effective at the frequencies below 100 GHz.

The single crystal of RuAs obtained by Bi-flux method shows obvious successive metal-insulator transitions at T_MI1~255 K and T_MI2~195$ K. The X-ray diffraction measurement reveals a formation of superlattice of 3x3x3 of the original unit cell below T_MI2, accompanied by a change of the crystal system from the orthorhombic structure to the monoclinic one. Simple dimerization of the Ru ions is nor seen in the ground state. The multiple As sites observed in nuclear quadrupole resonance (NQR) spectrum also demonstrate the formation of the superlattice in the ground state, which is clarified to be nonmagnetic. The divergence in 1/T_1 at T_MI1 shows that a symmetry lowering by the metal-insulator transition is accompanied by strong critical fluctuations of some degrees of freedom. Using the structural parameters in the insulating state, the first principle calculation reproduces successfully the reasonable size of nuclear quadrupole frequencies for the multiple As sites, ensuring the high validity of the structural parameters. The calculation also gives a remarkable suppression in the density of states (DOS) near the Fermi level, although the gap opening is insufficient. A coupled modulation of the calculated Ru d electron numbers and the crystal structure proposes a formation of charge density wave (CDW) in RuAs. Some lacking factors remain, but it shows that a lifting of degeneracy protected by the non-symmorphic symmetry through the superlattice formation is a key ingredient for the metal-insulator transition in RuAs., Comment: 10 pages, 10 figures

High-pressure and high-field electron spin resonance (ESR) measurements have been performed on a single crystal of the orthogonal-dimer spin system SrCu$_{2}$(BO$_{3}$)$_{2}$. With frequencies below 1 THz, ESR signals associated with transitions from the singlet ground state to the one-triplet excited states and the two-triplet bound state were observed at pressures up to 2.1 GPa. We obtained directly the pressure dependence of the gap energies, finding a clear first-order phase transition at $P_{c}=1.85\pm0.05$ GPa. By comparing this pressure dependence with the calculated excitation energies obtained from an exact diagonalization, we determined the precise pressure dependence for inter- ($J'$) and intra-dimer ($J$) exchange interactions considering the Dzyaloshinski-Moriya interaction. Thus this system undergoes a first-order quantum phase transition from the dimer singlet phase to a plaquette singlet phase above the ratio $(J'/J)_{c}=0.660\pm0.003$.

We developed a practical useful method for force- and torque-detected electron spin resonance (FDESR/TDESR) spectroscopy in the millimeter wave frequency region. This method uses a commercially available membrane-type surface-stress (MSS) sensor. The MSS is composed of a silicon membrane supported by four beams in which piezoresistive paths are integrated for detecting the deformation of the membrane. Although this device has a lower spin sensitivity than a microcantilever, it offers several distinct advantages, including mechanical strength, ease of use, and versatility. These advantages make this device suitable for practical applications that require FDESR/TDESR.

Magnetization, specific heat, and electrical resistivity measurements have been performed on polycrystalline samples of a new cubic compound, Ce6Pd13Zn4. This compound exhibits metallic behavior and is classified as a Kondo-lattice system. The trivalent Ce ions are responsible for the antiferromagnetic transition at TN = 3.3 K and the phase transition at \(T'_{\text{N}} = 1.3\) K with the formation of superzone gaps. The increase in magnetic susceptibilities below TN and the considerably large value of the specific heat divided by temperature (1.25 J·Ce-mol−1·K−2) imply the existence of non-ordered Ce magnetic moments due to the geometrical frustration on the octahedral Ce sublattice.

S=1/2 one-dimensional chain and dimer system Cu3Mo2O9, in which the super-exchange network forms one-dimensional corner-sharing tetrahedoron of Cu2+ ion, has been investigated by high field ESR measurements using the powder sample and the pulsed magnetic field up to 40 T at 2.0 K. The high field ESR measurements with wide frequency range suggest the existence of the magnetic phase transition at 8 T. Three ESR modes appear above 18 T, which corresponds to the magnetization jump. The ground state of Cu3Mo2O9 will be discuss.

High-frequency ESR technique using a microcantilever is reported. In our technique, an electromagnetic wave is irradiated at a sample-mounted cantilever via oversized waveguide, and ESR absorption is mechanically detected as a change of magnetic torque of the sample. The estimated spin sensitivity was 109 spins/G at 80 GHz. We also demonstrate multi-frequency ESR measurement of a µm-size sample at 315 GHz by cantilever detection.

We have performed photoluminescence (PL) measurements on magnetic semiconductor GaAs:Er,O under pulsed magnetic fields up to 60 T at 4.2 K. We have succeeded in observing the Zeeman effect of the 4 I 13/2→4 I 15/2 PL transition of the Er3+ in the high magnetic field region. The effective g-factor of the dominant PL transition is estimated to be g eff=1.54±0.04. This value is in reasonable agreement with the theoretical value based on the crystal field theory.

Development of multi-extreme electron spin resonance (ESR) measurement system is in progress in Kobe. We have installed the pulsed magnetic field up to 55 T and our high field ESR system can cover the frequency region from 30 GHz to 7 THz. Our aim is to extend our high field ESR system to the multi-extreme ESR measurement system by combining low temperature, high pressure and nano techniques, and the combination with the high pressure is focused in the paper. High pressure can be achieved up to 1.4 GPa by using the transmission type piston cylinder pressure cell. We have succeeded in combining the high field and the high pressure. As an example, the pressure dependence of the spin gap in SrCu2(BO3)2, S=1/2 Shustally-Sutherland dimer system, observed by our multi-extreme ESR measurement is presented. This measurement is the direct and precise measurement of the spin gap, and the spin gap decreased from 723 GHz (34.7 K) to 581 GHz (27.9 K) at 1.2 GPa.

Our recent developments in highly sensitive high-frequency electron spin resonance (ESR) using a microcantilever are reviewed. ESR signals of a Co Tutton salt microcrystal (

Noda H, Iso H, Irie F, Sairenchi T, Ohtaka E, Ohta H (Osaka University, Osaka, Japan; Harvard School of Public Health, Cambridge, MA, USA; Ibaraki Prefectural Office, Ibaraki; Dokkyo Medical University School of Medicine, Tochigi; Ibaraki Health Service Association, Ibaraki; Japan). Gender difference of association between LDL cholesterol concentrations and mortality from coronary heart disease amongst Japanese: the Ibaraki Prefectural Health Study. J Intern Med 2010; 267:576–587. Objective. The aim of this study was to examine whether LDL cholesterol raises the risk of coronary heart disease in a dose–response fashion in a population with low LDL-cholesterol levels. Design. Population-based prospective cohort study in Japan. Subjects and main outcome measures. A total of 30 802 men and 60 417 women, aged 40 to 79 years with no history of stroke or coronary heart disease, completed a baseline risk factor survey in 1993. Systematic mortality surveillance was performed through 2003 and 539 coronary heart disease deaths were identified. Results. The mean values for LDL-cholesterol were 110.5 mg dL−1 (2.86 mmol L−1) for men and 123.9 mg dL−1 (3.20 mmol L−1) for women. Men with LDL-cholesterol ≥140 mg dL−1 (≥3.62 mmol L−1) had two-fold higher age-adjusted risk of mortality from coronary heart disease than did those with LDL-cholesterol

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.

Sn-doped CaAl2S4 polycrystals and single crystals were synthesized by solid state reaction and chemical transport reaction method, respectively. They showed broad photoluminescence (PL) spectra in the visible region under the ultraviolet excitation and their luminescence color was pale yellow under the excitation at 325 nm. Three excitation bands at 3.67, 3.80, and 3.91 eV and three emission bands at 1.75, 1.93, and 2.15 eV were observed in photoluminescence excitation and PL spectra at 16 K. These bands were attributed to Sn ions which formed Tl+-type impurity center. For the application to white LED, Ce was co-doped into CaAl2S4:Sn polycrystals to enhance blue emission. As a result, Sn (0.5 mol%) and Ce (0.5 mol%) co-doped CaAl2S4 polycrystals showed white luminescence with chromatic coordinates of (0.393, 0.392) and (0.364, 0.343) under the excitation at 325 and 330 nm, respectively. The highest quantum efficiency of 43% was obtained for Sn (0.1 mol%) and Ce (0.5 mol%) co-doped CaAl2S4 polycrystals under 320 nm excitation. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Background— Few studies have examined the association between low levels of low-density lipoprotein (LDL) cholesterol and risk of intraparenchymal hemorrhage. Methods and Results— A total of 30 802 men and 60 417 women, 40 to 79 years of age with no history of stroke or coronary heart disease, completed a baseline risk factor survey in 1993 under the auspices of the Ibaraki Prefectural Health Study. Systematic mortality surveillance was performed through 2003, and 264 intraparenchymal hemorrhage deaths were identified. LDL cholesterol levels were calculated with the Friedewald formula. Persons with LDL cholesterol ≥140 mg/dL had half the sex- and age-adjusted risk of death due to intraparenchymal hemorrhage of those with LDL cholesterol Conclusions— Low LDL cholesterol levels are associated with elevated risk of death due to intraparenchymal hemorrhage.

We report results of the study of the recently discovered magnetic resonance in CeB6, which is characteristic to the phase II in the magnetic phase diagram of this strongly correlated heavy fermion metal. Experiments were carried out in a wide frequency range /2=44-360 GHz in magnetic field up to 30 T. It is found that the previously reported magnetic resonance exists at all frequencies studied and the g-factor for this resonance increases with frequency from g(/2=44 GHz)~1.55 to g(/2>250 GHz)~1.7. In addition to the aforementioned mode of magnetic oscillations an additional magnetic resonance with the g-factor 1.2-1.3 is detected for the frequencies exceeding 200 GHz. This effect may be a consequence of a complicated magnetic structure of the phase II, which is not foreseen in the standard models of the low temperature magnetic ordering in CeB6.

A recently discovered magnetic resonance in the orbitally ordered phase of CeB6 (orbital ordering resonance) is studied in a wide frequency range v = 44–360 GHz. The g-factor for this resonance was found to increase with frequency from g(v = 44 GHz) ∼ 1.55 to g(v > 250 GHz) ∼ 1.7. In addition to the orbital ordering resonance, a new magnetic resonance with a g-factor of 1.2–1.3 was detected for frequencies exceeding 200 GHz.

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.

Doping of CuGeO3 by 2% Co was found to cause a new magnetic resonance, which has anomalous polarization characteristics. In the Faraday geometry, where a microwave field B ω is directed along certain crystallographic directions, this mode is suppressed, which indicates that the character of magnetic oscillations in this mode differs strongly from standard spin precession. This resonance coexists with the EPR on Cu2+ chains and is likely to be caused by an unknown collective mode of magnetic oscillations of an antiferromagnetic quantum S = 1/2 spin chain.

Unprecedented anionic Fe(III) spin crossover (SCO) complexes involving a weak-field O,N,O-tridentate ligand were discovered. The SCO transition was evidenced by the temperature variations in magnetic susceptibility, Mossbauer spectrum, and coordination structure. The DFT calculations suggested that larger coefficients on the azo group in the HOMO-1 of a ligand might contribute to the enhancement of a ligand-field splitting energy. The present anionic SCO complex also exhibited the light- induced excited-spin-state trapping effect.

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.

During the summer of 1955, mass arsenic poisoning of bottle-fed infants occurred in the western part of Japan due to contaminated milk powder, and more than 100 died; some childhood victims were later found to suffer from neurological sequelae in adolescence. This unique incident enabled us to explore infancy as a critical period of arsenic exposure in regard to developmental neurotoxicity and its possible persistence through adulthood. The purpose of this work is to evaluate the association between developmental arsenic exposure and the neurological outcomes more than 50years later. We conducted a retrospective cohort study during the period from April 2012 to February 2013 in two hospitals in Okayama Prefecture, Japan. The study sample consisted of 50 individuals: 27 known poisoning victims from Okayama Prefecture, and 23 non-exposed local controls of similar age. In addition to neurological examination, we adapted a battery of neurophysiological and neuropsychological tests to identify the types of brain functions affected by early-life arsenic exposure. While limited abnormalities were found in the neurophysiological tests, neuropsychological deficits were observed. Except for Finger tapping, all test scores in the exposed group - Vocabulary and Block Design from Wechsler Adults Intelligent Scale III, Design memory subtest from Wide Range Assessment of Memory and Learning 2, and Grooved pegboard test - were substantially below those obtained by the unexposed. The exposed group showed average performance at least 1.2 standard deviations below the average for the controls. Exposed participants performed less well than controls, even after exclusion of subjects with recognized disabilities or those with a high level of education. Adults who had suffered arsenic poisoning during infancy revealed neuropsychological dysfunctions, even among those subjects not recognized as having disabilities. Developmental neurotoxicity due to arsenic likely results in permanent changes in brain functions.

We have made a survey of ceramics for the inner parts of the transmission-type pressure cell to achieve the high pressure and the high transmission in THz range. By using the optimal combination of ZrO$_{2}$-based ceramic and Al$_{2}$O$_{3}$ ceramic, we have succeeded in obtaining the pressure up to 1.5 GPa and the frequency region up to 700 GHz simultaneously. We show the high-pressure ESR results of Shastry-Sutherland compound SrCu$_{2}$(BO$_{3}$)$_{2}$ as an application. We observed the direct ESR transition modes between the singlet ground state and the triplet excited states up to the pressure of 1.51 GPa successfully, and obtained the precise pressure dependence of the gap energy. The gap energy is directly proved to be suppressed by the pressure. Moreover, we found that the system approaches the quantum critical point with pressure by comparing the obtained data with the theory. This result also shows the usefulness of high-pressure ESR measurement in THz region to study quantum spin systems.

The microscopic magnetic properties of high-quality GdN thin films have been investigated by electron spin resonance (ESR) and ferromagnetic resonance (FMR) measurements. Detailed temperature dependence ESR measurements have shown the existence of two ferromagnetic components at lower temperatures, which was not clear from the previous magnetization measurements. The temperature, where the resonance shift occurs for the major ferromagnetic component, seems to be consistent with the Curie temperature obtained from the previous magnetization measurement. On the other hand, the divergence of line width is observed around 57 K for the minor ferromagnetic component. The magnetic anisotropies of GdN thin films have been obtained by the analysis of FMR angular dependence observed at 4.2 K. Combining the X-ray diffraction results, the correlation between the magnetic anisotropies and the lattice constants is discussed.

Magnetic properties of Er-doped GaAs (GaAs:Er) and Er,O-codoped GaAs (GaAs:Er,O) have been investigated by using superconducting quantum interference devices (SQUID) magnetometer at low temperature. In M-H curves of GaAs:Er,O, a characteristic magnetization due to the codoping with Er and O was observed at 2 K, while GaAs:Er exhibited much smaller magnetization. The saturation magnetization of GaAs:Er,O slightly increased with Er concentration. These results were discussed in relation to an atomic configuration formed selectively around Er3+ ions in GaAs:Er,O. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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.

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.

Studies of novel quantum effects in quantum spin systems by high field ESR will be reviewed. High field ESR measurements of the Haldane system Y2BaNiO5 doped with nonmagnetic ion Mg2+have been performed. We have succeeded in resolving the ESR of finite Haldane chains using the high resolution feature of our high field ESR, and the direct information about the spin correlation in the Haldane chain at low temperature is obtained for the first time.

Anomalous polarization characteristics of magnetic resonance in CuGeO3 doped with 2% Co impurity are reported. For the Faraday geometry, this mode is damped for the microwave field B ω aligned along a certain crystallographic direction, showing that the character of magnetic oscillation differs from the standard spin precession. The observed resonance coexists with the ESR on Cu2+ chains; it is argued not to be caused by “impurity” EPR, as previously claimed, but to correspond to a previously unknown collective mode of magnetic oscillations in an S = 1/2 AF quantum spin chain.

The aim of this study was to assess the therapeutic efficacy of the serotonin norepinephrine reuptake inhibitor (SNRI), milnacipran, on both cognitive impairment and depression in post-stroke depression (PSD) patients. A total of 18 PSD patients, approximately 3 months after stroke, were divided into two groups, milnacipran and control. A total of 10 patients were assigned to the milnaciprane group and eight were assigned to control group. Their cognitive impairment and mood symptoms were measured using the Mini-Mental State Examination (MMSE) and Hamilton Depression Rating Scale (HAM-D) both at the time of admission and at discharge, an interval of approximately 3 months. This study examined the changes in both MMSE and HAM-D scores during the study period. A significant time-by-group interaction for results of the MMSE was observed, although there was no significant difference between the two groups on the HAM-D. Amelioration of cognitive impairment was greater in the milnacipran group than the control group. For PSD patients, milnacipran is effective in improving cognitive dysfunction.

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)

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)

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)

Sol–gel method followed by calcination at temperatures of 300–900 °C was used to obtain a series of LiMn2O4 samples with varying amounts of chemical and structural defects while preserving a constant Li:Mn atomic ratio. The physicochemical and structural properties of the samples were characterized by X-ray diffraction (XRD), thermal gravimetry analysis–mass spectrometry (TGA–MS), differential scanning calorimetry (DSC), and Raman spectroscopy techniques. These results were correlated with separately performed high-frequency EMR measurements on the same samples. The oxidation number of Mn ions changes as compared with the stoichiometric spinel composition LiMn2O4. These changes, induced by the removal or incorporation of oxygen, were analyzed and correlated with the appearance or disappearance of the cubic to orthorhombic phase transition at around room temperature. The phase transition occurs only if the concentration of vacancies (cationic or anionic) is below the limit necessary to form sufficient majority of perfect MnO6 octahedra of the high symmetry, Oh7. Disturbance of this high local symmetry, being a condition for Jahn–Teller distortion, seems to also be the decisive factor in suppressing the phase transition that is regarded to be responsible for electrical capacity fading during cell cycling.

We calculated the total energy of ferromagnetic (FM) and antiferromagnetic (AFM) GaN:Mn, GaAs:Mn, Ge:Mn and Si:Mn with various distribution of Mn atoms. It is found that the formation of Mn–N–Mn–N chain-like fragments largely lowers the total energy of GaN:Mn. Exchange interaction in the chains has AFM character, so this mechanism can result in a significant decrease of the Curie temperature of GaN:Mn. Our optical calculations show that the formation of such chain-like fragments introduces features in intragap absorption and can be observed in optical measurements. In GaAs:Mn, Ge:Mn and Si:Mn this mechanism is not efficient and the formation of the chains of Mn atoms has no significant effect on Curie temperature.

For the CuGeO3 single crystals doped with 1% of Fe the quantum critical behavior in a wide temperature range 1–40 K is reported. The critical exponents for susceptibility along different crystallographic axes are determined: α = 0.3 4 (B||a and B||c) and α = 0.3 1 (B||b). The description of the temperature dependences of the linewidth and g-factor could be obtained in the Oshikawa–Affleck theory assuming that staggered component of the magnetic moment is located predominantly along b-axis. Possible arguments favoring the competition between effects of the staggered field and antiferromagnetic ordering are provided.